Canadian Code Rules for Motor Branch Circuits (from the 2015 edition)
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- čas přidán 8. 09. 2024
- Applying ten code rules from the Canadian Electrical Code to a motor branch circuit to calculate FLA, disconnect size and location, control size, overload size, wire size, overcurrent size and tap conductor size.
very useful for motor calculation, and easy to understand the section 28.
studying for my second year code final now! thank you for your service
Incredibly pace, material, and skill!
Awesome step by step tutorial
THANKS for sharing your knowledge ❤️ very easy to understand
So good material! Thank you!
that was an amazing vidoe, thanks alot Mr Luke
Very informative. Thank you
Great job, it was a very interesting lecture
Thank you Sir for sharing your knowledge.
Great content! super helpful !
Great stuff!
thank you
Good job.
hope could have more videos for cec. it help us understand the 900 pages code book.lol. thanks for the video.
Yeah I agree it would help. I do these videos as I teach the subject in my own classes. Unfortunately I don't teach code for quite awhile. However there are other people who do. Try checking out schulerruler on youtube, he teaches at the same institution as I do.
@@lukivr thanks
Great lesson in a nutshell. Thank you, Luke! I assume you forgot to refer to T13 at the end of step 9
when you wanted to choose 90A. Right?
REFERENCE BOOK TO REFER SIMILAR THINGS.PLEASE !
FLC is not interchangeable with FLA sir. FLA is on the nameplate, and is used to calculate overload protection. FLC is given in the nec tables 430.248-250 and is used to calculate the over current protection device and size conductors. There is also terminal rating limitations. This is only according to the NEC, excuse me if you are working off of a different standard. This difference is key, especially when taking any code exam.
Really? Table 430 is pretty close to our T44 in Canada. These are just approximations for current from hp and voltage, but the nameplate current will always trump these when available. Here's what the CEC says for sizing the OC, OL and wire. 28-106 size the wire not less than 125% of the full load current rating of the motor. 28-200 size the overcurrent using the rated full load current of the motor. 28-306 size the overload device using the full load current rating of the motor. Full load current rating can be shortened to FLC which is also synonymous with full load amperage (FLA) - one is using the property (current) and the other is using the unit (amps). Most motors just say A or AMPS on them, at least the ones I've worked with. We use the terms FLA and FLC interchangeably and it only makes common sense to do so. For example, to calculate for a breaker or conductor you would need to look at the "A" box on the motor nameplate. This nameplate data can be called FLA or FLC, just semantics in my world. If you can express in your own words how these terms could be different, I would be interested, but don't give me some copy and pasted information that you don't fully understand. I don't want my students confused.
Was not copied and pasted, just from the code. In the US students must properly calculate these values and know the difference between these values to pass an exam. Per the NEC you MUST use the tables in the book to size OCPD. If that is confusing somehow I'm sorry. In the field everyone takes 125% of the nameplate to size breakers and wire, and you would be perfectly safe doing so. For those who are testing for Journeyman or Master electrical licenses there is a key distinction. You shouldn't be teaching anyone if you don't or can't understand that, saying these terms are interchangeable is incorrect. 125% of the nameplate FLA and the FLC tables do not always correspond.
@@mikehammond3793 I know there are differences between the US and Canada (i.e. imperial vs metric, conventional flow vs electron flow, NEC vs CEC) and this could very well be one of those nuances. I am hoping that it is obvious that I am teaching using rules from the Canadian Electrical Code and any astute American student should be wary of this. Just like I tell my students that use the left hand rule for current direction (hinged on electron flow) to be wary of any (typically US) sites that use conventional flow. In the community where I teach, we get our students to look up motor currents (which you call FLC) in the code tables often. However, it does say in the CEC that these values are guides only and where exact values are required always use the values on the motor nameplate (which you call FLA). This is done regardless if its in the classroom or out in the field, but again that is what we, collectively not just me, as a community of teachers do at our institution for apprentices, journeymen and master electricians. Since our code refers to the full load current rating of the motor it appears to combine the meanings of FLC and FLA in your world. It is nice to see someone passionate about electrical code but it's hard to discuss when we are referring to different texts. Thanks for your input and bringing this issue to light. I will make it more obvious that I'm teaching from the CEC.
If Equipment was rated for 90 deg C termination, 28-104 (C) says i have to rate all my wires to 75 deg c ?? what if rated for 60deg terminations??
Sorry, I missed this question 10 months ago. The simple answer is you can't use 60C rated wire direct to the motor. Table 37 shows the minimum conductor insulation for the different motor types. This is because motors can run hot.
sir do you teach online class?
Not clear on a Step#2 You choose AWG8 Is it a size of single wire? or 50A /3? 17A per phase?(per wire?)
yeah, that's a good question about 3 phase devices. First., let's try relating your question to a 100A single phase house panel which has 2 hots and a neutral conductor. Do you split the 100A in half to size the 2 hots? No, we size each hot conductor based on the 100A (typically two #3s - 1 red and 1 black). This is because if the loads are balanced the 100A that goes through line 1 will come back on line 2. Same goes for 3 phase motors which are also balanced loads. When we have a calculated ampacity of over 40A the smallest wire is a #8 from Table 2 (@ 75C). All 3 phase motors have 3 wires going to them (they don't have a neutral) and each wire is #8 for the above motor. The reason why is because the 40+ amps that the motor can draw is pulled through each wire and even though it happens at different times each wire must be able to handle that amount of current.
In other words, 3 phase devices don't take the total rated current and divide that equally among the conductors. Instead, EACH wire must handle the rated current.
@@lukefretwalker9096 Thank you! What about an AC Servo Motors. Do they obey the same rules as regular AC motors? If the manufacturer of the VFD or servo motor Drives recommends nominal of MCB. do I need to consider these recommendations?
@@maximgleboff6515 i don't know enough about servo motors and drives to answer your question. I do know, in general, that it's wise to follow the manufacturers specs of any equipment you're installing. Sorry I couldn't be more helpful.
@@lukefretwalker9096 Yep I got totally confused with manual.
Sir can help me to know, what is the size of Isolation Switch.
The isolation switch is a stand alone switch which is sized according to 28-602 1). For the motor above which has an FLA of 32.2A, a moulded 3-phase switch, for example, would have to be at least 37.03A (115%) so a 40A switch would work in reality since it would be hard to find a 38A switch. Rule 28-200 does not apply to this switch because it is not being used as circuit protection. An isolation switch is only used to disconnect the motor for maintenance purposes when it is not under load. Also see 28-200 3) for larger motors.
I'm guessing you meant FLC instead of FLA which is found on the motor nameplate.
I find that those 2 terms are interchangeable. FLC = full load current and FLA = full load amps mean the same thing. Some people also include RLC = rated load current which is found more often on compressors (which are also motors). Most of the motor nameplates that I've looked at usually just have AMPS or A listed. Any current listed on a motor is assumed to be at full load. There is no prevalent standard when it comes to how the manufacturers label their equipment, but it should make sense.
I was going to say that :)
@@lukivr RLA Is used on compressors because they are suction gas cooled and not air cooled like most motors. At least that's what I was taught.
You keep referring to part #9 as an overcurrent device. But it is not an overcurrent device in this application. It is a short circuit/ground fault protective device. Overcurrent protection is provided by the overloads on the starter.
Hey Russell, thanks for your comment. This appears to be a matter of semantics between your learning community and mine. I agree that in this application a fuse is mainly used to protect against a short circuit (either line to line or line to ground) but we use table 29 in the CE code to size this fuse. Table 29 is titled "Rating or setting of overcurrent devices for the protection of motor branch circuits". Whether we agree or not, that is the terminology that the code book uses. For motor overload protection, table 25 refers to overload devices (part #5).
This can be confusing because the general definition of an "overcurrent" is any current above rated which could be either an overload (current slightly above rated) or short-circuit (very high current). I do agree that because of how a fuse (or breaker) is sized in motor circuits, they will no longer protect against overloads in the circuit, but we still call these devices overcurrent devices regardless of how they function in this application. This means that we also need an overload device to protect against the overloads (and not short circuits) for motor circuits.
Perhaps there are different meanings to these same terms where you live, but this is how we do it where I live.
@@lukivr yeah I get that’s how it is, but it could be very confusing for someone trying to learn. They may think you are sizing two OC devices for the motor when that is really not what’s going on. NEC always refers to them as SC/GF devices in this situation because that’s what they are. A 90A breaker won’t provide overcurrent protection to 75* #8 conductors. Anyway, you’re correct; it’s just semantics but I just don’t want anyone getting confused. Thank you for the lesson.
Very helpful. Thank you!