And yet, as a fellow electrician I immediately cringed when I saw the hookup to the main disconnect. Bare copper sticking out at varying lengths and no ferrule in sight. Not using ferrules at this day and age is just asking for problems, they are cheap, easy to crimp and they even ensure proper lengths so that no bare copper should or could stick out. The conduit run looked great, but it seemed they ran out of time when hooking up, cause that looked pretty shoddy.
In my experience doing data none of that info will get passed on to the next tech that comes out amd whoever it is will have to figure it all out again
Dude, you are definitely the Louis Rossman of HVAC. Yeah, maybe there are technicians out there who are better, but almost none of them put their content out for ANYONE to see and learn from.
Not everyone has time or desire to create content after working long hours in the heat and smoke and other elements. 60+ hours per week is more than enough. Get home, kick off the boots, wash away the blood, sweat, and tears, have a hot meal and cold beer, and get some rest for the next day.
Just discovered this guy. Very impressed. I love the world we live in. Where pros show us their secrets and let us be these next generation jack of all trades.
He made several errors in his testing methods, got incorrect readings due to those errors and luckily it headed him in he right direction anyway, this guy has enough knowledge to eventually get him to the problem but his failure to follow the prescribed test procedure we are taught could (and did) mislead him, to note also that his action of energising the unit before checking supply could in itself have fried certain components and PCB boards, I am an electrical engineer and I do this on all sorts of machinery for a living, machinery I sometimes have no working knowledge of, this guy seems to only deal with AC units so he should be more refined and follow a known procedure for the units which he failed to do.
From what I understand that's kind of how you start out within the field when your new, I'm hopefully going to be hired soon for an AC company and one of their requirements is to be teamed up with a veteran tech who shows you the ropes and how they do things. Even though I've already attended an hvac school (ATI) schools can only you prepare you for so much.
Chris, it’s been my experience that various embedded controllers will brick themselves if there is a power sag while they are starting up. (And with capacitors in their power supplies, a brief interruption shows up as a power sag.). I’ve experienced this with various network devices, especially consumer versions. I’m not a HVAC tech, so I can’t speak about those controllers, but these days, computers are computers. A power cycle is one of the first things we do. On a high quality controller, the power on self test will then tell you if there are hardware issues. But many times a reboot brings the device back to its senses again. Keep up the good work and try to get some rest.
A job like this also great for an apprentice to help with, any bizarre or nonstandard issue let’s the apprentice see how someone with experience will talks the problem. You can teach standard process all day long, but the best thing to teach is how to learn and discover.
@@danforsyth365 I've only heard the term brick mean "permanently ruined" such as w/ a failed firmware update essentially preventing further attempts. The term originated w/ hard drives serving new duty as door stops.
As a 25+ year fire alarm tech, I have to say I love videos like these from competent technicians, especially in sister trades. Great video! Liked and subscribed. Can wait to see more content. Well done sir.
Circuit protection was oversized, Chris showed the max protection 90A on the equipment and they are using 125A fuses. Sat there and melted instead of blowing fuses.
When the first unit burnt out there would have been an arc drawn. Arcs will produce a lot of EMI some of which will be conducted down the mains and may not be trapped by circuit protection as they will only be relatively small. The pulses can make their way through the transformer onto the circuit board and cause the lock up
Wow. An entire video where the equipment was all actually working correctly from a refrigeration standpoint. AMAZING considering what you usually have to fix. Great video. Thanks man!
I like that heartbeat led, easy to implement sanity check. If I ever make an industrial board I'll be sure to add one. Maybe some voltage indication LEDs if the accountants allow it :)
Speaking from experience on this, either one of two things I would do. 1. Pull all the existing wire out, mark the burnt wire and replace that leg. 2. Pull existing wire and then refeed with entirely new wire. You are not going to be able to pull the single wire out in that conduit. Frankly speaking, that conduit is undersized for whats in there.
Logic boards can be very sensitive to power glitches. It's always worth doing the Computer Engineer's Power Cycle reset first off if a logic board is behaving oddly.
I'm a BMS/BAS guy and i love learning stuffs like this with the HVAC and Electrical guys whenever i got the chance. Doing T&C for new buildings gets me exposed to many new stuffs and it helps me to troubleshoot problems better. Not doing that anymore nowadays but troubleshooting problems gives you a kind of satisfaction that i dont really get with other jobs. Nice detailed video btw.
when i was a working man this kind of stuff always happened when i had 3 more calls to run. Your right fix it correctly or not at all. I had something like this happen. In ended i splice the wires and covering with electrical tape.We wanted a electrician to repair, but for some reason nothing was done for months. Finally i disconnected the electric and they had to get a electrician. But me being a hero could have caused lots of problems. Who would be responsible if someone got shocked, that would be me!
For all of the refrigerant and mechanical issues we deal with, I always appreciate these occasional electrical mysteries. It's so satisfying once you find the cause, especially if you've already narrowed it down before you laid eyes on it. Some of my go-to issues were the Trane Voyager disconnects that always wore out, and the York package units that ran the blower wire against a hard piece of angle steel and would rub through the jacket into a direct short.
That's unlikely. There is a higher chance of a brown out condition (it's California, after all) and those were the two units actively running. Unless your breaker for the first RTU failed to trip that is. Even then, it should trip the main for the building. It's very difficult for a single piece of equipment to brown out a building by itself (unless it's a factory. That's a whole different animal.)
@@jman0870 and thats how you can burn stuff up. Low voltage means increased amps. So if its on a borderline connection due to age/corrosion/barely specced another 20 amps which would easily be drawn if the voltage dipped to say 170 volts from 210 on a 90 amp rated circuit you can end up with weird situations.
@@PantherSerpahin I literally said brown out condition dude. By brownout I meant building wide, not a brownout cause by a different RTU. That is highly unlikely and bordering on impossible.
As an electrician I just wanted to say kudos to you for doing so much leg work for the electrician! However the electrician himself did a shoddy job connecting the main switch. Copper wire NEVER should stick out so much out of the switch. Touch safety is blown out of the window with this one. It probably isn't that much of a deal because no one will ever need to work on that switch for a long time, but it just saddens me that people rush their work like that, a proper connection could have been the cherry on the cake. Amazing video though!
Electrician not HVAC but I love content like this because it helps to know how other trades typically handle their side of the work so I can finish my work in a way that makes it easier for y'all after the fact just like you did by providing info ahead for the electrician (much appreciated). Me and our crew always try to think of the guys coming in after us regardless of their trade and I wish everyone did that.
PC power supplies have a software 'circuit breaker' function. After some power surges, they'll lock into an 'off' mode, and you have to remove all power from the unit, let the residual power drain from the board (hold power button to short it, or wait 5-10 minutes for caps to drain), then plug back in. I've seen the same behaviour on computer controller boards in other equipment as well (phone systems, gate controllers, etc). So, it's a BIT more involved than a straight reboot, but when someone calls me about a system not powering up, I always tell them to unplug it from the wall for 10 minutes, then try again, and call me if it didn't work.
You, Sir, are a real craftsman like in the tales of old, when people wanted to be proud of what they do and didn't just klutz things together and write a bill. I salute your great work ethics.
I am a technician for a HVAC company in Florida(not going to promote where) with 17+ years in and you sir did a fantastic job diagnosing those units, along with letting your apprentice get hands on. My thought on what happened is when the one wire that was burnt, arced to ground and forced a short across that specific panel, which being in California didn't seem out of the ordinary, so nobody was the wiser, causing the other unit to sense a power issue, mostly sounds like coincidence that those 2 units were more than likely the only ones running at that moment and purely luck. Those L****x style units' boards are very sensitive, and give a lot of information, but are fairly stout boards, so I'm fairly sure your diagnoses is correct in that the board is likely ok, and just did its job.
Another stellar episode. My back ground is leather work. I do enjoy watching other people ply their trade and knowledge to solve and correct problems. Thanks for the videos.
I probably mentioned this once before... My house has a heat pump system (mid-Atlantic). One winter's day I happened to be by my electrical panel and heard the HVAC backup heat relay click. I then started hearing ticking from the electrical panel. That's not good! Killed power, took the panel face off and found one of the breaker feed lug screws loose. Probably saved myself from a dangerous situation and expensive repair.
If people were like you and listened and acted on weird noises in their equipment, cars, and so on, it would save so much on repairs and reduce hazards..
I love watching you work, my dude. I’ve been in the industry now for about 9mo, and have started considering what part I would like to get into as a niche, where I’m going to use my strengths, be my best at doing, and enjoy working the most. I enjoy all of it so far, but it’s the big commercial stuff that I find the most fun, and challenging, of what I’ve worked on thus far. Seeing you be so good and experienced at it, and rarely getting too frustrated (at least on camera 😏) has really got me thinking I’d like to start focusing my energies on the light commercial service side of things. I’d really need to up my electrical and refrigeration chops, but that’s all good. Thanks for being an inspiration and something to aspire to. Stay posting man, you’re doing some serious good for those of us just entering or thinking of joining the trade. COVID was a bit of a blessing in disguise for my work life and overall happiness. One. 🤙
@@manolotech1110 Thanks, loving it so far! Trying my hand at service any and every chance I get, but so many installs around this time here in Florida 🤦🏻♂️🤙 I actually have to go finish up an install tomorrow, solo, then head to another install the crew will have started. Should prove interesting!
Looking at that electrical junction connection, I would say that the problem wasn't originally a loose connection but instead was corrosion. The splices were all made of aluminum from the looks of it and aluminum corrodes faster than any other metal. That is why you have to use oxygen barrier grease when you make connections from aluminum to any other metal including the bolts in the splice lugs. The corrosion over time caused the connection to go higher resistance and over time and thermal cycles caused it to meltdown.
This isn't true for any AL wire made in the last 30 years. Modern AL wire is an alloy that doesn't corrode like the old stuff. Using anti ox greas on it is pointless and a waste of money. NEC does not require it, and using it can actual be detrimental to the integrity of the splice.
@@hgbugalou Well all I can say is that the Aluminum feeder wire in the main panel of my house is only 12 years old and it is already showing signs of oxidation and corrosion in a conditioned and heated space where the humidity is kept at or below 50% year round. The corrosion would be far worse in a junction box on a roof that is subjected to the elements. If you use the corrosion inhibiting grease according to the manufactures specifications it will only improve the splice. That is precisely why underground and outdoor rated splice kit connectors are often filled with the stuff (even when splicing copper).
@@kuhrd under ground is a completely different ball game. As far as your feeder, You either got cheap and or old wire or another factor involved. For example, anti ox is a good thing if your deal with buildings near the ocean.
Aluminum forms an oxide barrier faster than you can ever add grease. It's a thin layer that prevents further oxidation and corrosion, unlike iron rust that can keep penetrating further. However, aluminum, like most metals, can experience galvanic corrosion. It can also get pitted corrosion from stress (like maybe that tight space, bends, and the constant vibration of the AC unit) which will allow corrosion to go deeper than the surface. Then there is any acid or alkaline that can also cause chemical reactions and corrosion. Since Chris works the Inland Empire I would assume salt water spray is a non issue since that shit is all desert. That doesn't mean there can't be another element getting in that box. My guess is just a poor splice with constant vibration eventually caused it to fail. The only thing bugging me is the looks of corrosion going up into the jacket, that seems to suggest some high or low pH chemical was around it. Then again, maybe the constant heating up due to resistance building up did that.
This may sound weird coming from a 17 year old who's considering being a wood worker but last night I rewired three of my (adoptive) great aunt's/uncle's touch lamps yesterday. I'm in Pennsylvania as a vacation and was supposed to go back to Illinois today, but the flight was canceled for an A/C issue with the plane; so now I'm stuck in PA for an eleventh day.
Not far from my house some people ripped apart a chiller. I will post details that I saw/assuming 2 compressor, carrier unit, 4 condenser fan motors, maybe 460v chiller, contactors were ripped apart but there were 2 3pole 200a breakers laying on the ground. Only thing remaining was a part of the metal frame and the condenser fan motors and holders. Edit: 30rb70 208v. There was a third breaker but it is broken apart. Pretty big unit!
Never watched your channel, just showed up in my feed... thanks CZcams. They say, "those that can't do, teach" and I must say that is true in most cases but you "can do AND teach while doing"! Very impressive, loved your logical approach and getting it right. Keep up the good work.
Man I gotta agree. Weve got a 30 ton Lennox like the one in the video for our lobby at a movie theater, it runs full tilt most of the time it's above the low-mid 80s outside and it's just really something to stand and listen to all 3 of those giant scroll compressors purring. The condenser drain is literally like a garden hose, just absolutely dumping water. Really something to see.
A couple days ago I replaced a capacitor in a condensing unit. Pushed in the contactor to do what you call the bump start, verified that it works. Turned it on at the thermostat, the system went into what I thought was a very long delay. No 24v at the contactor coil whatsoever. Went inside to check the indoor unit, appeared to be plugged in, verified 120v at the outlet, then opened up the unit assuming I’d find a low voltage issue. The unit had no power whatsoever. Drove me insane for about 15 minutes not being able to figure out. I followed the plug into where it goes into the unit, only to discover that the cord was for the condensate pump. I looked down on the ground to see the actual cord for the unit, on the ground and unplugged (by the customer). Plugged it in and it ran just fine. Man I really wanted to slap myself after that. But in my defense, I was jelly brained from the heat, exhausted and 10 hours into my day. But I should’ve noticed that right away. 😂😂😂🤣🤣🤣
@@mtucker3401 this was a split system, and was referring to the indoor unit/furnace/air handler/ whatever the hell people call them. The condenser itself had a proper 240v supply. The contactor coil in the condenser wasn’t getting the 24v signal from the indoor unit which had no power because it was unplugged. Did I explain that well enough?
@@gregmercil3968 I think those tend to be hardwired as well but obviously indoor blower units and logic board power can vary. That's probably the confusion.
@@etherealrose2139 long story short, the indoor unit was unplugged and took a few agonizing minutes to realize that this was why. I confused the condensate plug for the indoor unit’s plug. That whole day sucked! 🤣
Love the "not my meter" chapter. I use that as my back up meter, since I have watched the channel my truck its now full of fieldpieace tools! Keep the goods coming !
So glad my trade school provided a few small Fieldpiece tools to start with at graduation, as I hadn’t heard of them prior. Since then, it’s pretty much one of two brands I prefer to buy first choice (Navac being the other) - now that I’ve really started gathering my personal service tools.
When I check continuity to ground I like to start by putting both probes on the sheet metal. It ensures that the meter is in the correct mode and working and that the probe I keep on the same point for the rest of the testing has contact.
Fault finding is an art. You might now how to install and commission something, but finding faults requires a much more in depth knowledge of how it works. It’s a dance. This guy is amazing.
As others have said, the shorting/arcing on the one AC could have affected the second AC. Breakers and fuses are mainly there to protect the wires against overcurrent. You can still get a lot of stuff past basic breakers. The short could have caused noise or voltage spikes/drops. Depending on if/how the wires touched and arced in that box it could have dragged voltage down on a leg or caused all sorts of weird power at the second AC. Especially if they're right next to each other in the main distribution board or a subpanel. Or maybe some combination of circumstances
This is a perfect example, in my opinion, of why HVACR technicians are better at finding electrical faults and understanding complex circuits than most fully qualified electricians.
Yeah, as an electrician myself, I disagree with that wholeheartedly. Maybe some of these more modern electricians that don’t no they arse from there elbow but I would’ve found that no problem. Also, there is not a cat in hell as chance a lightning strike caused those connectors to melt more than likely when they shorted it could’ve caused a spike and Corrupted the other Unit
That customer is so lucky they didn't burn their place down.. I work on garage doors and door openers and I've seen a garage burn down from a loose connection on the outlet going to a garage door opener. I cant believe it didnt fry that circuit board. I know that cant be cheap. Good work.
I will be going live on CZcams this evening 9/6/21 @ 5:PM (pacific) to discuss my recent uploads and answer questions from the chat, Come over and check it out czcams.com/video/HZjHAYTULSo/video.html
Dont mind the apprentice being there. Some of the info you give to them may not be in the video had they not been there. More info is never a bad thing. Keep up the good work.
We've had several power issues here in NC in recent weeks. Had a Holiday Inn that blew a fuse in the disconnect in half for one unit, and fried control boards in two other units. Of course the power company will never admit fault, but power issues can cause an array of crazy issues.
Got called for flickering lights in a cooling rack, turns out theres barely 200 v on the first phase coming into the main 100a breaker, when it should be 220-230. Still not sure whether it was the electrical companys fault or the building just added way too much stuff over the years to the point where the voltage drop was exessive
This is why Surge Suppressors should be Mandatory equipment in all Main Distribution Panels so any Power Surges hitting the building from the Grid will get caught by the suppressor before it hits the building's equipment.
Thats why our company (in germany) if I recall correctly even has power quality monitoring in place to proove that the problems initiated from the primary side of our transformer and not from our company internal grid...
I am a 72 yo from Australia relatively new to this channel and I am interested as i spent many years in the industry ranging from an heating tech, Air-conditioning, refrigeration, mechanical services as a whole as installer to design to engineer. I am amazed at the equipment and accessible information you now available to you. I do find that design for restaurants would not meet Australian codes and the lack of through being put into equipment installation and placement to reduce the effect of kitchen exhaust being drawn into the units. Having been on both sides I always endeavoured to designing to minimise maintenance issue. You certainly do a great job and I thank you how you pass on your experience to others in the industry that are willing to login and listen.
I work in kuwait as hvac technician. Here 90 percent of pcb board lockdown is caused by high pressure rise. Like outdoor fan malfunction filter dryer restrictions etc. Your videos are very informative 👍
Very professional! Hopefully the owner watched this video, because they should have noticed the way you diagnosed the system and handed off the duties, then came back to finish the duty bad ass! Thanks for this vid! We as HVAC-R techs are basically electricians but our responsibility is box to unit, electrician responsibility is pole to box! Obviously the unit not working is why you got the call, but this time it was the box great work!
MAN i wish HVAC guys etc would work with electricians like this more often, makes the job so much easier and leaves less figuring to the job and makes it go smoother
Again, I appreciate your diagnostic approach. My career was in emergency medicine (earlier in automechanics) and later I added a career in computer networking. My point is that the same set of skills works in all of them. Big picture, cause before complaint. It's understanding the process. It applies in many disciplines, probably all. In each understanding the components is important but the process is the same.
Well, doesn't matter what the unit uses as max amperage, this only defines how large the unit's breaker is. The fuses in the fuse box below the roof define how large the wire needs to be or they need to be sized lower. But this might not be future proof, that's why most customers run larger wires to the roof and have a smaller breaker there. :)
It is good industry practice to have a bigger wires. Some units runs 24/7 (not on that video or location...) and these wires can heat up. Bigger cross section helps to avoid that kind of trouble. Cost is higher so typically nobody does not take a extra care
@@simplemechanics246 well, this only makes sense if the wire is the same size from the grid right to the consumers. This isn't the case here. Instead the wires are stepped down on each breaker.
@@RubenKelevra A larger diameter translates into more conductor. More conductor means less resistance. Less resistance means 1) less voltage drop, and 2) less heat generated within the conductor.
Wow, actually checking the voltages at the transformers?! You were supposed to throw the parts cannon at it first...don't you know how this works? In all seriousness, great troubleshooting, sometimes we need to step back and go "anything else that can cause this issue?"
I love when the customer "thinks" its a call back and plays those ntc games and attempts to hold you hostage because they question what you did and they have no understanding of how mecahical ac systems work😑😑
"Fix it yourself. That means climbing up on the hot ass roof and verifying the other unit is off and the one worked on is purring along." Maybe that'll give them pause.
Hindsight , in a perfect world , he would have checked the other ac unit and got it running , instead of phlucking with power cables that he wasn’t going to fix .
Such an Arc will create enormous High Frequency Content on the Lines which can travel upwards through the breakers and onto different branches of the electical system. It can affect other devices, sometimes even other buildings if the event is large enough. Usually such content is filtered with caps and filters on the input side of the power supplies but they age and it‘s also dependent on length of the cable runs. So I can totally imagine how the meltdown could trigger a power fault on the electronics of the other system, while not affecting all systems on the roof.
It's tough to get business and finance guys to understand what a cap bank is for, since the up-front cost is so large, and their statistics classes told them these "one in a hundred-thousand" catastrophic failures are why we pay insurance premiums. Prevention? That's not cost-effective!
When doing a continuity check. I always retest the meter and probes at the end of the line of testing. So to confirm the meter is still working and readings confidence is high.
As a computer technician I love the old "Turn it off and on again" fix. Sometimes a restart/reset just refreshes the circuit and firmware and can fix many issues.
You are right that that board is messed up. The heartbeat is generally done with a piece of code running on the microcontroler, a watchdog timer or an interrupt. If none of that low level stuff can run, and you don't see a heart beat, the microcontroller is not working. These micros can do thousands or millions of calculations between heartbeats, so if it can't manage to blink a LED, it has crashed. I would also guess that lightning messed up all of those boards or caused them to crash. Great video by the way.
Great video, as always. Really liked when you punted to the electrician. Way better idea to run seal-tite than snake #2awg thru EMT! PS your humility is what makes you freaking awesome 👍. Keep up the good work.
I am a general handy-man, and this stuff is way above my skill set. I want to tell you how much I enjoyed the video. Your pleasant voice and logical process was informative and enjoyable. There are a lot of videos out there with good information, but many have presentations that are annoying and distracting. There is not much on CZcams that will make me sit and pay attention for over 30 minutes!
As an electrician, I appreciate your rare wisdom. The power surge that pushed the funkiness over the edge in the box might have pushed the second unit's 3rd phase enough to cause an internal imbalance that caused its system to trip. Even with separate breakers, the units are connected at the transformer feeding the building. The flow is real.
Instead of a continuity test with an ohmmeter, I use a megger. It will pick up shorts to ground that a 9 volt battery can’t find. It will also catch intermittent shorts such as a bare wire in close proximity to ground. A meggers high voltage will cause it to arc to ground.
Good job on your analysis. I'm glad the board manufacturer took the time and expense to build in lockout circuitry for voltage sag/spikes. Maybe since they are rooftop units which have inherent issues with such things they added those safeties to the system. The hardware I use will plow thru the sags/spikes, which are very seldom in a BAS control panel at the floor level.
As a computer engineer (software engineering / electrical engineering) and having worked with multiple embedded systems over the past 18 years.. I think what happened was that there was a brownout or similiar, and that caused one unit to have a meltdown. So what happened was one unit lost one phase, while another unit was affected by it. Usually when you have sub-boards controlled by a master board (the board that the sub (or daughter) boards sit on), the master board usually sync's them up and sends a clock signal to all of them. So I theorize that on the first unit, losing a phase caused them all to lock up. I'm not clear on the design on the boards, so that's all I can theorize. And then the first unit caused the second unit to have an issue due to a "brown-out" condition - i.e. when you have arcing and a meltdown it can cause a voltage disruption across the 3 phases. So I theorize that the second unit's boards got out of sync and the firmware couldn't account for that - so the daughter boards heartbeat signal sped up because of that. There are ways to get stuff back in sync (in the case of the second unit) - by having watchdog systems that would do a complete reset of the system if anything goes wrong. Losing power for a brief moment could also have lead to the individual RAM in each unit being corrupted leading to the board crashing (i.e. why heartbeat signal blinking fast in some but not in others) so.. It's hard to say without knowing how the board is designed. You did the right thing by powering-on / powering-off. If it's a hardware issue - i.e. wrong voltage, then things wont change by powering-on / powering-off. If its a software issue or inter operating issue (i.e. you have a few different boards with their own processor and memory) then powering on / powering off will solve it by getting everything back in sync. In short, the first unit failed because of wrong voltage on one of the phases. The second unit most likely failed because of the first unit affecting it's power input via a brown-out method which caused some of the modules (daughter / sub boards) to glitch and stop talking to the master board. Then the whole thing locked up. The master board should have a way to reset everything. It didn't in this case because it was also locked up (fast heartbeat). If they added a simple hardware watchdog timer, then they could have avoided the whole issue. I.e. it's basically a counter that counts down from 5 minutes and the microprocessor sends a signal every 10-30 seconds to reset the counter. If something hangs, and the count reaches 0, then the reset line is turned on and everything gets reset, including the watchdog counter.
My hypothesis as a dumb guy who fixes toilets for a living is that installer error may have installed the first melted lug poorly and also installed the lugs in the second box poorly. Some sort of surge or brown-out made the poor connections worse, but actually melted the first and not the second. I would have wanted to at least open the second junction box to confirm that one wasn't cooked as well even though it was (currently) getting good voltage.
It looks like the lug that was used for splicing the wire is aluminum.. That's a huge NO NO. Aluminum expands and contracts dramatically due to temperature changes, it's also a dissimilar metal to the copper wire. It was a very poor choice for the splice, it should have been made of copper instead. Expansion and contraction cycles over time caused it to loosen, and then become a hot spot further exacerbating the problem, and in addition to all this aluminum has a lower temperature melting point. Aluminum wire, aluminum lugs, copper clad aluminum wire are cheap alternatives to copper but pretty much all fail in the long run.. CCA or copper clad aluminum wire is showing up more often today. Avoid it because the aluminum at the core can oxidize causing it to turn to powder, and at some point the wire will fail because the copper clad surface cannot carry the current alone. If you're maintaining or repairing equipment that is fed with aluminum wire, do your customer a favor. Keep a container of noalox on your truck or van. Back the screws out of the connection, pull out the wires if you can and use a small brush to thoroughly cover the wire strands with noalox, also coat the screw threads because if the lugs are also aluminum, the screws can bind in the threads due to the tendency of threads to gall in aluminum. Tighten everything down properly and it will be fine for several decades to come.
Aluminum expands and contracts, yes, but this isn't aluminum wire used with non-tension connections. This is copper wire with aluminum connector blocks, with iron screw points. I've seen these stay solid for decades. CCA is okay, depending on the usage. For example, my car jumper/booster cables are 4 gauge CCA. It let me have longer cables for a lower price, and the amount of usage isn't going to make me run into the 'aluminum wire shorts' problem. CCA is even okay for network cabling - if you have the right connectors (which not much does). It's just a royal PITA to work with afterwards, especially if it's not labeled as such. You shouldn't get progressive oxidation in the aluminum core of wires, unless the copper layer has been compromised (that's a different problem), or it's a really poor grade of aluminum. Remember, aluminum is insanely reactive. If it didn't corrode instantly upon exposure with the air, it would burst into flame (like lithium or sodium). So it always already _has_ an oxide layer as soon as it's plated with copper. it's just that there shouldn't be any further reaction due to the copper coating.
@@tbelding What I said about aluminum is still the case, whether it be the wires OR the lugs. Lugs will expand and contract due to temperature change more than other materials. My experience is that there are very few panels, buss bars etc that will actually use aluminum, plus the fact that it's a soft metal and prone to galling of the threads of any set screws regardless of the materials they're made of. My experience of working in the trade for many decades is that most lugs are some kind of copper alloy with a cadmium plating to protect against oxidation. Perhaps what you 'thought' was aluminum lugs were really cadmium plated copper or some other copper alloy which is quite stable regarding expansion and contraction rates due to thermal causes. I've never ever seen any wire splicing lugs, split bolts etc that were made of aluminum. That would be madness, and welcoming a failure.
I Always check the incoming power on the transformer first. Sounds like you have quite a large voltage imbalance. Time to call the electrician. Good video.
Thanks bud!! I will be going live on CZcams this evening 10/18/21 @ 5:PM (pacific) to discuss my recent uploads and answer questions from emails, CZcams comments and the LiveChat come over and check it out czcams.com/video/V4Zo3F1p8KA/video.html
Really appreciate your professionalism! It's something you don't see a lot of these days. It's always not their problem or just don't want to do their job.
Do those controller boards have built 3 phase monitors? The rapid flashing tends to make one think they do. I’d bet when the other units feed burned through it had a significant drop on that phase, and tripped the monitors/monitor. Enjoy the videos! You guys be safe out there!
Not a pro tech but have had enough experience, as a union stagehand, with 3-phase. Your meter work on verifying voltage and continuity is a lesson for all of us. Can't believe power was still getting through the offending box. Great video!
You made the best right call handing the electrical issue off to an electrician. If it had been a simple issue of just replacing the splice connector yeah you could have done it. But since the cables were damaged, the best solution was to completely replace the entire run for that phase. Also, huge kudos to the electrician for for re-running all three phases with different colors for the three phases! Bravo!
Great trouble shooting! Starting at the most likely till you found the problem! Agree with your decision to have the electrician do the wires while you concentrate on HVAC calls! Work smart not hard and get more done and make more money!
A guess on the 2nd board is that the surge made it go into panic mode. There are circuits to prevent the board from shorting, over current etc out and if you trip it, it goes into "panic". Usually, as you know with this one, it did fine after a reset.
I’m surprised that your code allows splices on 100amp circuits in a small box like that. Certain to fail UK installation regulations! Here you would have supply lugged into a local weatherproof isolator then out in armoured flexible to the AC unit. But here we have 415v across phases so a bit more danger.
I love watching your videos even though I have never been in your field. I was a coin op tech for around 40 years working on everything like candy machines, video games, juke boxes and even slot machines (and almost anything that takes coins or bills). I guess I like watching someone that knows what they are doing that is not a "Swapnition" (someone that just changes parts until it works) I myself was always lead in my field (last guy to be called when no one else could figure it out) and it's a joy to watch someone like that work through a problem. Another person might have just said oh, the LED's are flashing, must be the board and then changed it out (at I am assuming great expense) and then turned it on and validated their ability because hey, it works now.
We just had 400 ton York chiller loose operating display go blank (#3 of 4) after power blink checked incoming power ok cycled power at switch gear still out recycled at unit system came up cleared phase loss unit started up and ran. Electronics sometimes do what they want.
As a computer consultant, who has had to work with other computerized systems (phone systems, etc), I can attest to some of the other comments here. The initial blowout likely surged through the local power network, which gave dirty signal power to the other units. Some probably managed to reset themselves, but in this case, the system locked down into a "I have no idea what to do, so I'm going to do nothing and run a warning light" mode. If there had been a power outage _after_ that occurrence, the board would have lost residual power, allowing a clean startup. I had an exploded outlet that did just that to the battery backup connected near to it. The UPS went into a lockdown mode, requiring it to be unplugged, powered off, plugged back in again, then powered up - after which it worked fine. If you have _any_ piece of electrical equipment that's doing strange things, one of the first things to do for troubleshooting (besides checking that the input voltage is correct) is completely disconnect all power and leave it to sit long enough for all the capacitors to discharge. On a PC, that can involve popping the coin battery out as well as pulling the power cord. On a car, it involves disconnecting the battery terminals. (I always do both, many only do the positive) (Your car will go through a learning cycle after that, so don't panic about weird performance until it lasts more than 15 minutes of active driving). In this case, shutting down the main breaker does it. I'm actually astonished that nobody on site _turned the stupid thing off_ once they knew it wasn't working. If something electrical has failed/isn't working, and you don't know how to troubleshoot it - turn it off! I keep telling customers that as well "Unplug it, and I'll come as quickly as I can" (then I find they've been flipping it on and off until something worked, switched parts around, etc). It was definitely interesting watching your breakdown/troubleshooting method. I've never worked with 3-phase power, so it's still very unusual for me.
I used to know a maintenance assistant that would use old dental tools to straighten chiller fins on huge roof top AC units in an OCD fashion lol.... maybe the same guy.
As an electrician, I really appreciate the things you did for the guy that had to come and fix it. Its not every time I see that
And yet, as a fellow electrician I immediately cringed when I saw the hookup to the main disconnect. Bare copper sticking out at varying lengths and no ferrule in sight.
Not using ferrules at this day and age is just asking for problems, they are cheap, easy to crimp and they even ensure proper lengths so that no bare copper should or could stick out.
The conduit run looked great, but it seemed they ran out of time when hooking up, cause that looked pretty shoddy.
In my experience doing data none of that info will get passed on to the next tech that comes out amd whoever it is will have to figure it all out again
Dude, you are definitely the Louis Rossman of HVAC. Yeah, maybe there are technicians out there who are better, but almost none of them put their content out for ANYONE to see and learn from.
Being able to explain things verbally is a skill in itself!
Not everyone has time or desire to create content after working long hours in the heat and smoke and other elements. 60+ hours per week is more than enough. Get home, kick off the boots, wash away the blood, sweat, and tears, have a hot meal and cold beer, and get some rest for the next day.
@@whoisderf Exactly why his efforts to make these videos happen is so admirable.
Just discovered this guy. Very impressed. I love the world we live in. Where pros show us their secrets and let us be these next generation jack of all trades.
He made several errors in his testing methods, got incorrect readings due to those errors and luckily it headed him in he right direction anyway, this guy has enough knowledge to eventually get him to the problem but his failure to follow the prescribed test procedure we are taught could (and did) mislead him, to note also that his action of energising the unit before checking supply could in itself have fried certain components and PCB boards, I am an electrical engineer and I do this on all sorts of machinery for a living, machinery I sometimes have no working knowledge of, this guy seems to only deal with AC units so he should be more refined and follow a known procedure for the units which he failed to do.
Kudo's for having an apprentice and getting him some on hands experience with you in support. Best way to learn across all trade crafts.
From what I understand that's kind of how you start out within the field when your new, I'm hopefully going to be hired soon for an AC company and one of their requirements is to be teamed up with a veteran tech who shows you the ropes and how they do things. Even though I've already attended an hvac school (ATI) schools can only you prepare you for so much.
Chris, it’s been my experience that various embedded controllers will brick themselves if there is a power sag while they are starting up. (And with capacitors in their power supplies, a brief interruption shows up as a power sag.). I’ve experienced this with various network devices, especially consumer versions. I’m not a HVAC tech, so I can’t speak about those controllers, but these days, computers are computers. A power cycle is one of the first things we do. On a high quality controller, the power on self test will then tell you if there are hardware issues. But many times a reboot brings the device back to its senses again.
Keep up the good work and try to get some rest.
A job like this also great for an apprentice to help with, any bizarre or nonstandard issue let’s the apprentice see how someone with experience will talks the problem. You can teach standard process all day long, but the best thing to teach is how to learn and discover.
@@zacharynetzer819 Learning by doing.
@@danforsyth365 I've only heard the term brick mean "permanently ruined" such as w/ a failed firmware update essentially preventing further attempts. The term originated w/ hard drives serving new duty as door stops.
As a 25+ year fire alarm tech, I have to say I love videos like these from competent technicians, especially in sister trades. Great video! Liked and subscribed. Can wait to see more content. Well done sir.
Hello there sir, I had something I was interested in asking you. My email is in the contact page of my channel if you felt like responding! Take care.
Circuit protection was oversized, Chris showed the max protection 90A on the equipment and they are using 125A fuses. Sat there and melted instead of blowing fuses.
When the first unit burnt out there would have been an arc drawn. Arcs will produce a lot of EMI some of which will be conducted down the mains and may not be trapped by circuit protection as they will only be relatively small. The pulses can make their way through the transformer onto the circuit board and cause the lock up
Almost exactly what I was going to say and better put.
Well said
once that connection blew out it sent out over voltages to other ac cause it lock down
Precisely. That thing would be a total spark gap radio scrambling the microprocessors.
I agree. There's an amazing amount of noise coming from an arcing connection.
Wow. An entire video where the equipment was all actually working correctly from a refrigeration standpoint. AMAZING considering what you usually have to fix. Great video. Thanks man!
I like that heartbeat led, easy to implement sanity check. If I ever make an industrial board I'll be sure to add one. Maybe some voltage indication LEDs if the accountants allow it :)
Speaking from experience on this, either one of two things I would do.
1. Pull all the existing wire out, mark the burnt wire and replace that leg.
2. Pull existing wire and then refeed with entirely new wire.
You are not going to be able to pull the single wire out in that conduit. Frankly speaking, that conduit is undersized for whats in there.
Entirely undersized. All conductors cannot exceed 40% of the conduit with exceptions for stuff like the whip-it style cable used as a replacement.
Logic boards can be very sensitive to power glitches. It's always worth doing the Computer Engineer's Power Cycle reset first off if a logic board is behaving oddly.
especially if their not getting proper voltage from a improper wire connection
I'm a BMS/BAS guy and i love learning stuffs like this with the HVAC and Electrical guys whenever i got the chance. Doing T&C for new buildings gets me exposed to many new stuffs and it helps me to troubleshoot problems better. Not doing that anymore nowadays but troubleshooting problems gives you a kind of satisfaction that i dont really get with other jobs. Nice detailed video btw.
when i was a working man this kind of stuff always happened when i had 3 more calls to run. Your right fix it correctly or not at all. I had something like this happen. In ended i splice the wires and covering with electrical tape.We wanted a electrician to repair, but for some reason nothing was done for months. Finally i disconnected the electric and they had to get a electrician. But me being a hero could have caused lots of problems. Who would be responsible if someone got shocked, that would be me!
For all of the refrigerant and mechanical issues we deal with, I always appreciate these occasional electrical mysteries. It's so satisfying once you find the cause, especially if you've already narrowed it down before you laid eyes on it.
Some of my go-to issues were the Trane Voyager disconnects that always wore out, and the York package units that ran the blower wire against a hard piece of angle steel and would rub through the jacket into a direct short.
That box hasn't been looked at in years, probably handyman electric lol
that sparky did a decent job on that run
ill bet the second unit saw a voltage drop for a second and locked out due to low voltage on one phase
That's unlikely. There is a higher chance of a brown out condition (it's California, after all) and those were the two units actively running. Unless your breaker for the first RTU failed to trip that is. Even then, it should trip the main for the building. It's very difficult for a single piece of equipment to brown out a building by itself (unless it's a factory. That's a whole different animal.)
@Demonitized Boi care to elaborate? Wires burn up during brownouts. Motors, boards, and transformers burn up during voltage spikes.
@@jman0870 and thats how you can burn stuff up. Low voltage means increased amps. So if its on a borderline connection due to age/corrosion/barely specced another 20 amps which would easily be drawn if the voltage dipped to say 170 volts from 210 on a 90 amp rated circuit you can end up with weird situations.
@@PantherSerpahin I literally said brown out condition dude. By brownout I meant building wide, not a brownout cause by a different RTU. That is highly unlikely and bordering on impossible.
As an electrician I just wanted to say kudos to you for doing so much leg work for the electrician! However the electrician himself did a shoddy job connecting the main switch. Copper wire NEVER should stick out so much out of the switch. Touch safety is blown out of the window with this one. It probably isn't that much of a deal because no one will ever need to work on that switch for a long time, but it just saddens me that people rush their work like that, a proper connection could have been the cherry on the cake. Amazing video though!
Electrician not HVAC but I love content like this because it helps to know how other trades typically handle their side of the work so I can finish my work in a way that makes it easier for y'all after the fact just like you did by providing info ahead for the electrician (much appreciated).
Me and our crew always try to think of the guys coming in after us regardless of their trade and I wish everyone did that.
If you haven't already watch this one.... czcams.com/video/wJMiyg7gfMA/video.html
IT: "Have you tried turning it off and on again?"
HVAC: "Have you tried turning it off and on again?"
Bahaha!
A lot of problems can be fixed this way. Digital circuits 'crash' from power dips and must be 'rebooted'.
Pretty standard for electronics
PC power supplies have a software 'circuit breaker' function. After some power surges, they'll lock into an 'off' mode, and you have to remove all power from the unit, let the residual power drain from the board (hold power button to short it, or wait 5-10 minutes for caps to drain), then plug back in. I've seen the same behaviour on computer controller boards in other equipment as well (phone systems, gate controllers, etc). So, it's a BIT more involved than a straight reboot, but when someone calls me about a system not powering up, I always tell them to unplug it from the wall for 10 minutes, then try again, and call me if it didn't work.
You, Sir, are a real craftsman like in the tales of old, when people wanted to be proud of what they do and didn't just klutz things together and write a bill. I salute your great work ethics.
I am a technician for a HVAC company in Florida(not going to promote where) with 17+ years in and you sir did a fantastic job diagnosing those units, along with letting your apprentice get hands on. My thought on what happened is when the one wire that was burnt, arced to ground and forced a short across that specific panel, which being in California didn't seem out of the ordinary, so nobody was the wiser, causing the other unit to sense a power issue, mostly sounds like coincidence that those 2 units were more than likely the only ones running at that moment and purely luck. Those L****x style units' boards are very sensitive, and give a lot of information, but are fairly stout boards, so I'm fairly sure your diagnoses is correct in that the board is likely ok, and just did its job.
Another stellar episode. My back ground is leather work. I do enjoy watching other people ply their trade and knowledge to solve and correct problems. Thanks for the videos.
I probably mentioned this once before...
My house has a heat pump system (mid-Atlantic). One winter's day I happened to be by my electrical panel and heard the HVAC backup heat relay click. I then started hearing ticking from the electrical panel. That's not good! Killed power, took the panel face off and found one of the breaker feed lug screws loose. Probably saved myself from a dangerous situation and expensive repair.
If people were like you and listened and acted on weird noises in their equipment, cars, and so on, it would save so much on repairs and reduce hazards..
I love watching you work, my dude.
I’ve been in the industry now for about 9mo, and have started considering what part I would like to get into as a niche, where I’m going to use my strengths, be my best at doing, and enjoy working the most. I enjoy all of it so far, but it’s the big commercial stuff that I find the most fun, and challenging, of what I’ve worked on thus far. Seeing you be so good and experienced at it, and rarely getting too frustrated (at least on camera 😏) has really got me thinking I’d like to start focusing my energies on the light commercial service side of things. I’d really need to up my electrical and refrigeration chops, but that’s all good.
Thanks for being an inspiration and something to aspire to. Stay posting man, you’re doing some serious good for those of us just entering or thinking of joining the trade. COVID was a bit of a blessing in disguise for my work life and overall happiness. One. 🤙
Good luck in the HVAC trade!
@@manolotech1110 Thanks, loving it so far! Trying my hand at service any and every chance I get, but so many installs around this time here in Florida 🤦🏻♂️🤙
I actually have to go finish up an install tomorrow, solo, then head to another install the crew will have started. Should prove interesting!
Looking at that electrical junction connection, I would say that the problem wasn't originally a loose connection but instead was corrosion. The splices were all made of aluminum from the looks of it and aluminum corrodes faster than any other metal. That is why you have to use oxygen barrier grease when you make connections from aluminum to any other metal including the bolts in the splice lugs. The corrosion over time caused the connection to go higher resistance and over time and thermal cycles caused it to meltdown.
This isn't true for any AL wire made in the last 30 years. Modern AL wire is an alloy that doesn't corrode like the old stuff. Using anti ox greas on it is pointless and a waste of money. NEC does not require it, and using it can actual be detrimental to the integrity of the splice.
@@hgbugalou Well all I can say is that the Aluminum feeder wire in the main panel of my house is only 12 years old and it is already showing signs of oxidation and corrosion in a conditioned and heated space where the humidity is kept at or below 50% year round.
The corrosion would be far worse in a junction box on a roof that is subjected to the elements. If you use the corrosion inhibiting grease according to the manufactures specifications it will only improve the splice. That is precisely why underground and outdoor rated splice kit connectors are often filled with the stuff (even when splicing copper).
@@kuhrd under ground is a completely different ball game. As far as your feeder, You either got cheap and or old wire or another factor involved. For example, anti ox is a good thing if your deal with buildings near the ocean.
@@hgbugalou just wondering since when did Nec say no need for anti ox grease. We are still required to use it .
Aluminum forms an oxide barrier faster than you can ever add grease. It's a thin layer that prevents further oxidation and corrosion, unlike iron rust that can keep penetrating further.
However, aluminum, like most metals, can experience galvanic corrosion. It can also get pitted corrosion from stress (like maybe that tight space, bends, and the constant vibration of the AC unit) which will allow corrosion to go deeper than the surface.
Then there is any acid or alkaline that can also cause chemical reactions and corrosion. Since Chris works the Inland Empire I would assume salt water spray is a non issue since that shit is all desert. That doesn't mean there can't be another element getting in that box.
My guess is just a poor splice with constant vibration eventually caused it to fail. The only thing bugging me is the looks of corrosion going up into the jacket, that seems to suggest some high or low pH chemical was around it. Then again, maybe the constant heating up due to resistance building up did that.
This may sound weird coming from a 17 year old who's considering being a wood worker but last night I rewired three of my (adoptive) great aunt's/uncle's touch lamps yesterday. I'm in Pennsylvania as a vacation and was supposed to go back to Illinois today, but the flight was canceled for an A/C issue with the plane; so now I'm stuck in PA for an eleventh day.
Not far from my house some people ripped apart a chiller. I will post details that I saw/assuming
2 compressor, carrier unit, 4 condenser fan motors, maybe 460v chiller, contactors were ripped apart but there were 2 3pole 200a breakers laying on the ground. Only thing remaining was a part of the metal frame and the condenser fan motors and holders. Edit: 30rb70 208v. There was a third breaker but it is broken apart. Pretty big unit!
Never watched your channel, just showed up in my feed... thanks CZcams. They say, "those that can't do, teach" and I must say that is true in most cases but you "can do AND teach while doing"! Very impressive, loved your logical approach and getting it right. Keep up the good work.
There's just something about the three stage units and how they sound that I just love
Man I gotta agree. Weve got a 30 ton Lennox like the one in the video for our lobby at a movie theater, it runs full tilt most of the time it's above the low-mid 80s outside and it's just really something to stand and listen to all 3 of those giant scroll compressors purring. The condenser drain is literally like a garden hose, just absolutely dumping water. Really something to see.
no wonder the poor thing's heart monitor light was lit like that, the poor thing was having a stroke lol.
A couple days ago I replaced a capacitor in a condensing unit. Pushed in the contactor to do what you call the bump start, verified that it works. Turned it on at the thermostat, the system went into what I thought was a very long delay. No 24v at the contactor coil whatsoever. Went inside to check the indoor unit, appeared to be plugged in, verified 120v at the outlet, then opened up the unit assuming I’d find a low voltage issue. The unit had no power whatsoever. Drove me insane for about 15 minutes not being able to figure out. I followed the plug into where it goes into the unit, only to discover that the cord was for the condensate pump. I looked down on the ground to see the actual cord for the unit, on the ground and unplugged (by the customer). Plugged it in and it ran just fine. Man I really wanted to slap myself after that. But in my defense, I was jelly brained from the heat, exhausted and 10 hours into my day. But I should’ve noticed that right away. 😂😂😂🤣🤣🤣
What kind of condenser are you working on that has a 120v plug??
@@mtucker3401 this was a split system, and was referring to the indoor unit/furnace/air handler/ whatever the hell people call them. The condenser itself had a proper 240v supply. The contactor coil in the condenser wasn’t getting the 24v signal from the indoor unit which had no power because it was unplugged. Did I explain that well enough?
Remember: Don't b so hard on yourself, others will do it for you
@@gregmercil3968 I think those tend to be hardwired as well but obviously indoor blower units and logic board power can vary. That's probably the confusion.
@@etherealrose2139 long story short, the indoor unit was unplugged and took a few agonizing minutes to realize that this was why. I confused the condensate plug for the indoor unit’s plug. That whole day sucked! 🤣
Love the "not my meter" chapter. I use that as my back up meter, since I have watched the channel my truck its now full of fieldpieace tools! Keep the goods coming !
Any port in a storm!
So glad my trade school provided a few small Fieldpiece tools to start with at graduation, as I hadn’t heard of them prior. Since then, it’s pretty much one of two brands I prefer to buy first choice (Navac being the other) - now that I’ve really started gathering my personal service tools.
When I check continuity to ground I like to start by putting both probes on the sheet metal. It ensures that the meter is in the correct mode and working and that the probe I keep on the same point for the rest of the testing has contact.
Fault finding is an art. You might now how to install and commission something, but finding faults requires a much more in depth knowledge of how it works. It’s a dance. This guy is amazing.
It is science. It is a methodology. Your lack of knowledge does not increase the complexity of the world around you.
As others have said, the shorting/arcing on the one AC could have affected the second AC. Breakers and fuses are mainly there to protect the wires against overcurrent. You can still get a lot of stuff past basic breakers. The short could have caused noise or voltage spikes/drops. Depending on if/how the wires touched and arced in that box it could have dragged voltage down on a leg or caused all sorts of weird power at the second AC. Especially if they're right next to each other in the main distribution board or a subpanel. Or maybe some combination of circumstances
This is a perfect example, in my opinion, of why HVACR technicians are better at finding electrical faults and understanding complex circuits than most fully qualified electricians.
Yeah, as an electrician myself, I disagree with that wholeheartedly. Maybe some of these more modern electricians that don’t no they arse from there elbow but I would’ve found that no problem. Also, there is not a cat in hell as chance a lightning strike caused those connectors to melt more than likely when they shorted it could’ve caused a spike and Corrupted the other Unit
That customer is so lucky they didn't burn their place down.. I work on garage doors and door openers and I've seen a garage burn down from a loose connection on the outlet going to a garage door opener. I cant believe it didnt fry that circuit board. I know that cant be cheap. Good work.
I will be going live on CZcams this evening 9/6/21 @ 5:PM (pacific) to discuss my recent uploads and answer questions from the chat, Come over and check it out czcams.com/video/HZjHAYTULSo/video.html
Dont mind the apprentice being there. Some of the info you give to them may not be in the video had they not been there. More info is never a bad thing. Keep up the good work.
We've had several power issues here in NC in recent weeks. Had a Holiday Inn that blew a fuse in the disconnect in half for one unit, and fried control boards in two other units. Of course the power company will never admit fault, but power issues can cause an array of crazy issues.
Got called for flickering lights in a cooling rack, turns out theres barely 200 v on the first phase coming into the main 100a breaker, when it should be 220-230.
Still not sure whether it was the electrical companys fault or the building just added way too much stuff over the years to the point where the voltage drop was exessive
This is why Surge Suppressors should be Mandatory equipment in all Main Distribution Panels so any Power Surges hitting the building from the Grid will get caught by the suppressor before it hits the building's equipment.
Thats why our company (in germany) if I recall correctly even has power quality monitoring in place to proove that the problems initiated from the primary side of our transformer and not from our company internal grid...
We've got a problem
You know that's a good video when they start like this.
Greats from Portugal, Stay Safe!
Yes
I am a 72 yo from Australia relatively new to this channel and I am interested as i spent many years in the industry ranging from an heating tech, Air-conditioning, refrigeration, mechanical services as a whole as installer to design to engineer. I am amazed at the equipment and accessible information you now available to you. I do find that design for restaurants would not meet Australian codes and the lack of through being put into equipment installation and placement to reduce the effect of kitchen exhaust being drawn into the units. Having been on both sides I always endeavoured to designing to minimise maintenance issue. You certainly do a great job and I thank you how you pass on your experience to others in the industry that are willing to login and listen.
Super awesome! I look forward to watching these videos like i anticipated watching GI Joe and Transformers when i got home from school as a kid.
Optimus Prime yeh baby!
I work in kuwait as hvac technician. Here 90 percent of pcb board lockdown is caused by high pressure rise. Like outdoor fan malfunction filter dryer restrictions etc. Your videos are very informative 👍
Very professional! Hopefully the owner watched this video, because they should have noticed the way you diagnosed the system and handed off the duties, then came back to finish the duty bad ass! Thanks for this vid! We as HVAC-R techs are basically electricians but our responsibility is box to unit, electrician responsibility is pole to box! Obviously the unit not working is why you got the call, but this time it was the box great work!
MAN i wish HVAC guys etc would work with electricians like this more often, makes the job so much easier and leaves less figuring to the job and makes it go smoother
Your apprentice is fortunate to have you as an instructor.
Again, I appreciate your diagnostic approach. My career was in emergency medicine (earlier in automechanics) and later I added a career in computer networking. My point is that the same set of skills works in all of them. Big picture, cause before complaint. It's understanding the process. It applies in many disciplines, probably all. In each understanding the components is important but the process is the same.
Well, doesn't matter what the unit uses as max amperage, this only defines how large the unit's breaker is.
The fuses in the fuse box below the roof define how large the wire needs to be or they need to be sized lower. But this might not be future proof, that's why most customers run larger wires to the roof and have a smaller breaker there. :)
It is good industry practice to have a bigger wires. Some units runs 24/7 (not on that video or location...) and these wires can heat up. Bigger cross section helps to avoid that kind of trouble. Cost is higher so typically nobody does not take a extra care
I've seen oversized wire in installation for two main reasons.
1) Future proofing, as mentioned above.
2) Less voltage drop/ improved safety factor.
@@darkwater72 how does a larger diameter increase safety? 🤔
@@simplemechanics246 well, this only makes sense if the wire is the same size from the grid right to the consumers. This isn't the case here.
Instead the wires are stepped down on each breaker.
@@RubenKelevra
A larger diameter translates into more conductor.
More conductor means less resistance.
Less resistance means 1) less voltage drop, and 2) less heat generated within the conductor.
Wow, actually checking the voltages at the transformers?! You were supposed to throw the parts cannon at it first...don't you know how this works? In all seriousness, great troubleshooting, sometimes we need to step back and go "anything else that can cause this issue?"
lol you got me at parts cannon.
@@ryanengle3188 lmao same. We say that around the office all the time cause some techs just love installing new stuff lol
i would have checked for voltage the moment i turned that disconnect back on.
Good guys always check volts.
This channel is super interesting. Never thought AC servicing would be this cool. side note: i have the exact same boxes as you.
Love that Simpson 260 on top of storage rack in your office!
I love when the customer "thinks" its a call back and plays those ntc games and attempts to hold you hostage because they question what you did and they have no understanding of how mecahical ac systems work😑😑
Do a video on dirty power
EXACTLY!
"Fix it yourself. That means climbing up on the hot ass roof and verifying the other unit is off and the one worked on is purring along."
Maybe that'll give them pause.
Hindsight , in a perfect world , he would have checked the other ac unit and got it running , instead of phlucking with power cables that he wasn’t going to fix .
I was wondering if you'd grown a third arm. That would certainly come in handy.
Such an Arc will create enormous High Frequency Content on the Lines which can travel upwards through the breakers and onto different branches of the electical system. It can affect other devices, sometimes even other buildings if the event is large enough. Usually such content is filtered with caps and filters on the input side of the power supplies but they age and it‘s also dependent on length of the cable runs. So I can totally imagine how the meltdown could trigger a power fault on the electronics of the other system, while not affecting all systems on the roof.
It's tough to get business and finance guys to understand what a cap bank is for, since the up-front cost is so large, and their statistics classes told them these "one in a hundred-thousand" catastrophic failures are why we pay insurance premiums. Prevention? That's not cost-effective!
NASA scientist?
love to see the next gen getting great hands on experience. kudos to the whole program!!!
When doing a continuity check. I always retest the meter and probes at the end of the line of testing. So to confirm the meter is still working and readings confidence is high.
As a computer technician I love the old "Turn it off and on again" fix. Sometimes a restart/reset just refreshes the circuit and firmware and can fix many issues.
I don’t even work any trades and I thought this was a cool video of things exploding. Now I can’t turn it off 🤦🏻♂️ good job!
You are right that that board is messed up. The heartbeat is generally done with a piece of code running on the microcontroler, a watchdog timer or an interrupt. If none of that low level stuff can run, and you don't see a heart beat, the microcontroller is not working. These micros can do thousands or millions of calculations between heartbeats, so if it can't manage to blink a LED, it has crashed. I would also guess that lightning messed up all of those boards or caused them to crash. Great video by the way.
Great video, as always.
Really liked when you punted to the electrician. Way better idea to run seal-tite than snake #2awg
thru EMT!
PS your humility is what makes you freaking awesome 👍. Keep up the good work.
Only legends watch the closing words part.
I am a general handy-man, and this stuff is way above my skill set. I want to tell you how much I enjoyed the video. Your pleasant voice and logical process was informative and enjoyable. There are a lot of videos out there with good information, but many have presentations that are annoying and distracting.
There is not much on CZcams that will make me sit and pay attention for over 30 minutes!
Usually you go around and check all the units to see if the fans are running or notice that something hasn't turned on, this time you didn't.
As an electrician, I appreciate your rare wisdom. The power surge that pushed the funkiness over the edge in the box might have pushed the second unit's 3rd phase enough to cause an internal imbalance that caused its system to trip. Even with separate breakers, the units are connected at the transformer feeding the building. The flow is real.
IMO great call! I don't sweep the floors, I don't expect the custodian to repair an issue. We all have our specialties and time is non-replaceable !
I will discuss this on my Livestream this evening 8/2/21 @ 5:PM (pacific) on CZcams come over and check it out czcams.com/video/DMdcdQaF-kU/video.html
excellent technician
you do good work
remember quality is better than quantity.
slow down be safe and live long
Instead of a continuity test with an ohmmeter, I use a megger. It will pick up shorts to ground that a 9 volt battery can’t find. It will also catch intermittent shorts such as a bare wire in close proximity to ground. A meggers high voltage will cause it to arc to ground.
Good job on your analysis. I'm glad the board manufacturer took the time and expense to build in lockout circuitry for voltage sag/spikes. Maybe since they are rooftop units which have inherent issues with such things they added those safeties to the system. The hardware I use will plow thru the sags/spikes, which are very seldom in a BAS control panel at the floor level.
I'm loving the format with the apprentice ☺️
As a computer engineer (software engineering / electrical engineering) and having worked with multiple embedded systems over the past 18 years.. I think what happened was that there was a brownout or similiar, and that caused one unit to have a meltdown. So what happened was one unit lost one phase, while another unit was affected by it. Usually when you have sub-boards controlled by a master board (the board that the sub (or daughter) boards sit on), the master board usually sync's them up and sends a clock signal to all of them. So I theorize that on the first unit, losing a phase caused them all to lock up. I'm not clear on the design on the boards, so that's all I can theorize. And then the first unit caused the second unit to have an issue due to a "brown-out" condition - i.e. when you have arcing and a meltdown it can cause a voltage disruption across the 3 phases. So I theorize that the second unit's boards got out of sync and the firmware couldn't account for that - so the daughter boards heartbeat signal sped up because of that.
There are ways to get stuff back in sync (in the case of the second unit) - by having watchdog systems that would do a complete reset of the system if anything goes wrong. Losing power for a brief moment could also have lead to the individual RAM in each unit being corrupted leading to the board crashing (i.e. why heartbeat signal blinking fast in some but not in others) so.. It's hard to say without knowing how the board is designed.
You did the right thing by powering-on / powering-off. If it's a hardware issue - i.e. wrong voltage, then things wont change by powering-on / powering-off. If its a software issue or inter operating issue (i.e. you have a few different boards with their own processor and memory) then powering on / powering off will solve it by getting everything back in sync.
In short, the first unit failed because of wrong voltage on one of the phases. The second unit most likely failed because of the first unit affecting it's power input via a brown-out method which caused some of the modules (daughter / sub boards) to glitch and stop talking to the master board. Then the whole thing locked up. The master board should have a way to reset everything. It didn't in this case because it was also locked up (fast heartbeat). If they added a simple hardware watchdog timer, then they could have avoided the whole issue. I.e. it's basically a counter that counts down from 5 minutes and the microprocessor sends a signal every 10-30 seconds to reset the counter. If something hangs, and the count reaches 0, then the reset line is turned on and everything gets reset, including the watchdog counter.
Watchdog timers, i remember that from my digital electronics class
My hypothesis as a dumb guy who fixes toilets for a living is that installer error may have installed the first melted lug poorly and also installed the lugs in the second box poorly. Some sort of surge or brown-out made the poor connections worse, but actually melted the first and not the second. I would have wanted to at least open the second junction box to confirm that one wasn't cooked as well even though it was (currently) getting good voltage.
Thank you for this content. It is really helpful for me as a EEE student, I have learnt much more from your videos than I could ever learn in a lab.
It looks like the lug that was used for splicing the wire is aluminum.. That's a huge NO NO. Aluminum expands and contracts dramatically due to temperature changes, it's also a dissimilar metal to the copper wire. It was a very poor choice for the splice, it should have been made of copper instead. Expansion and contraction cycles over time caused it to loosen, and then become a hot spot further exacerbating the problem, and in addition to all this aluminum has a lower temperature melting point. Aluminum wire, aluminum lugs, copper clad aluminum wire are cheap alternatives to copper but pretty much all fail in the long run.. CCA or copper clad aluminum wire is showing up more often today. Avoid it because the aluminum at the core can oxidize causing it to turn to powder, and at some point the wire will fail because the copper clad surface cannot carry the current alone.
If you're maintaining or repairing equipment that is fed with aluminum wire, do your customer a favor. Keep a container of noalox on your truck or van. Back the screws out of the connection, pull out the wires if you can and use a small brush to thoroughly cover the wire strands with noalox, also coat the screw threads because if the lugs are also aluminum, the screws can bind in the threads due to the tendency of threads to gall in aluminum. Tighten everything down properly and it will be fine for several decades to come.
CCA huh?
exactly, you can oversize any wire as long as you use the correct breaker and fuses for the unit.
Noalox.....
Aluminum expands and contracts, yes, but this isn't aluminum wire used with non-tension connections. This is copper wire with aluminum connector blocks, with iron screw points. I've seen these stay solid for decades. CCA is okay, depending on the usage. For example, my car jumper/booster cables are 4 gauge CCA. It let me have longer cables for a lower price, and the amount of usage isn't going to make me run into the 'aluminum wire shorts' problem. CCA is even okay for network cabling - if you have the right connectors (which not much does). It's just a royal PITA to work with afterwards, especially if it's not labeled as such.
You shouldn't get progressive oxidation in the aluminum core of wires, unless the copper layer has been compromised (that's a different problem), or it's a really poor grade of aluminum. Remember, aluminum is insanely reactive. If it didn't corrode instantly upon exposure with the air, it would burst into flame (like lithium or sodium). So it always already _has_ an oxide layer as soon as it's plated with copper. it's just that there shouldn't be any further reaction due to the copper coating.
@@tbelding What I said about aluminum is still the case, whether it be the wires OR the lugs. Lugs will expand and contract due to temperature change more than other materials.
My experience is that there are very few panels, buss bars etc that will actually use aluminum, plus the fact that it's a soft metal and prone to galling of the threads of any set screws regardless of the materials they're made of.
My experience of working in the trade for many decades is that most lugs are some kind of copper alloy with a cadmium plating to protect against oxidation.
Perhaps what you 'thought' was aluminum lugs were really cadmium plated copper or some other copper alloy which is quite stable regarding expansion and contraction rates due to thermal causes.
I've never ever seen any wire splicing lugs, split bolts etc that were made of aluminum. That would be madness, and welcoming a failure.
At 1:30 i thought "this guys so good he's got three hands". Really good work and safe work nice job
An arcing mains connection can induce highish voltage to the transformer secondary and raise a lot of hell on digital boards.
I Always check the incoming power on the transformer first. Sounds like you have quite a large voltage imbalance. Time to call the electrician. Good video.
I don't have a clue about anything in this video but it's interesting watching you find the cause of the issue and solve it. Subbed
Thanks bud!! I will be going live on CZcams this evening 10/18/21 @ 5:PM (pacific) to discuss my recent uploads and answer questions from emails, CZcams comments and the LiveChat come over and check it out czcams.com/video/V4Zo3F1p8KA/video.html
Really appreciate your professionalism! It's something you don't see a lot of these days. It's always not their problem or just don't want to do their job.
2:50 oh, those through-hole circuit boards are things of beauty. SO much more character than surface-mount!
Do those controller boards have built 3 phase monitors? The rapid flashing tends to make one think they do. I’d bet when the other units feed burned through it had a significant drop on that phase, and tripped the monitors/monitor. Enjoy the videos! You guys be safe out there!
Not a pro tech but have had enough experience, as a union stagehand, with 3-phase. Your meter work on verifying voltage and continuity is a lesson for all of us. Can't believe power was still getting through the offending box. Great video!
two legs were ok, third was open, so there was a "series" connection between the open leg and the other two.
I've never seen such a shiny looking group of PCBs 😅🤩
A real working man with real talent. Hats off to you.
Glad to see that you are taking the time for hands on training of someone else giving your knowledge and still making videos.
Keep up these vids! Educational and entertaining!
The short was not in an obvious place unlike the carrier units and the blower assemblies.
Sunday mornings with Chris, what else can I ask for? ;-) Thanks!
You made the best right call handing the electrical issue off to an electrician. If it had been a simple issue of just replacing the splice connector yeah you could have done it.
But since the cables were damaged, the best solution was to completely replace the entire run for that phase.
Also, huge kudos to the electrician for for re-running all three phases with different colors for the three phases! Bravo!
Well done for using different coloured cables, which should of been done in the beginning.
Great trouble shooting! Starting at the most likely till you found the problem! Agree with your decision to have the electrician do the wires while you concentrate on HVAC calls! Work smart not hard and get more done and make more money!
Awesome vid. I repaired locomotives electrical systems for 12 years. We ran into all types of problems like this.
Good deal for having your apprentice do some hands on.
I’m a bit late but best video yet! Interesting electrical fault, PCB glitched and the awesome sound of 3 stages starting up 😀👍
LUCKY!!!!!! ive heard bad stories about people kneeling down and touch the unit and that was the end!!!!!
A guess on the 2nd board is that the surge made it go into panic mode. There are circuits to prevent the board from shorting, over current etc out and if you trip it, it goes into "panic".
Usually, as you know with this one, it did fine after a reset.
when our equipment loses heart beat, cops gets sent to site, usually because someone wrapped a chain around the atm and drove off, very annoying
I’m surprised that your code allows splices on 100amp circuits in a small box like that. Certain to fail UK installation regulations!
Here you would have supply lugged into a local weatherproof isolator then out in armoured flexible to the AC unit.
But here we have 415v across phases so a bit more danger.
Some units are 600V.
yea true. 208x100 = 20.8kW, 415x100 = 41.5kW. 20.8kW with 415v will be safer as it will just be 50A
I love watching your videos even though I have never been in your field. I was a coin op tech for around 40 years working on everything like candy machines, video games, juke boxes and even slot machines (and almost anything that takes coins or bills). I guess I like watching someone that knows what they are doing that is not a "Swapnition" (someone that just changes parts until it works) I myself was always lead in my field (last guy to be called when no one else could figure it out) and it's a joy to watch someone like that work through a problem. Another person might have just said oh, the LED's are flashing, must be the board and then changed it out (at I am assuming great expense) and then turned it on and validated their ability because hey, it works now.
We just had 400 ton York chiller loose operating display go blank (#3 of 4) after power blink checked incoming power ok cycled power at switch gear still out recycled at unit system came up cleared phase loss unit started up and ran. Electronics sometimes do what they want.
As a computer consultant, who has had to work with other computerized systems (phone systems, etc), I can attest to some of the other comments here. The initial blowout likely surged through the local power network, which gave dirty signal power to the other units. Some probably managed to reset themselves, but in this case, the system locked down into a "I have no idea what to do, so I'm going to do nothing and run a warning light" mode. If there had been a power outage _after_ that occurrence, the board would have lost residual power, allowing a clean startup. I had an exploded outlet that did just that to the battery backup connected near to it. The UPS went into a lockdown mode, requiring it to be unplugged, powered off, plugged back in again, then powered up - after which it worked fine.
If you have _any_ piece of electrical equipment that's doing strange things, one of the first things to do for troubleshooting (besides checking that the input voltage is correct) is completely disconnect all power and leave it to sit long enough for all the capacitors to discharge. On a PC, that can involve popping the coin battery out as well as pulling the power cord. On a car, it involves disconnecting the battery terminals. (I always do both, many only do the positive) (Your car will go through a learning cycle after that, so don't panic about weird performance until it lasts more than 15 minutes of active driving). In this case, shutting down the main breaker does it.
I'm actually astonished that nobody on site _turned the stupid thing off_ once they knew it wasn't working. If something electrical has failed/isn't working, and you don't know how to troubleshoot it - turn it off! I keep telling customers that as well "Unplug it, and I'll come as quickly as I can" (then I find they've been flipping it on and off until something worked, switched parts around, etc).
It was definitely interesting watching your breakdown/troubleshooting method. I've never worked with 3-phase power, so it's still very unusual for me.
The one "thumbs down" must be a competitor of yours hahaha! Well done as always, brother! You're a brilliant tech.
I am learning lots of stuff watching you. I love your OCD work ethic.
I could use a little education on what superheating is.
I used to know a maintenance assistant that would use old dental tools to straighten chiller fins on huge roof top AC units in an OCD fashion lol.... maybe the same guy.
like your videos they help me a lot looking for things I tend to overlook.