Guy's, I've been in the electrical industry for 45 years and I treat everyday as a school day. I'm a full member of the IET and have to say your explanation has given me a level of clarity on the issue I didn't have before I watched this. Fantastic video liked and subscribed.
They use individual current transducers on the phase and neutral. It's measured electronically instead. Sadly this puts the onus on some electronics to operate rather than the intrinsic behaviour we see with type AC
That's the reason type AC RCDs are banned here in Germany for new installations since 1984. The common type in residentials here is the type A RCD or RCBO. For electric vehicle chargers you should use type B, or as I did it for myself at home: Type A RCD and the wallbox charger got the DC protection inside. Described nicely: "Persons don't test the RCDs often as they should". To my experience people are doing this almost never.
Here in Romania, a lot of debate is rising here among electricians. Type AC are most common, A are harder to find, B even harder :) I think that a good grounding and, eventually, a second separate grounding must be there
Cheers for this video chaps, I'm aware you guys have been working on getting this information out for some time. Great video, packed with information. Thanks again.
Really interesting, and excellent science teaching from Joe as always, and you’re wrong Joe, I always get to the end of your videos 🤓 .. you *and* JW, although I have occasionally repurposed JW when the sleeping pills 💊 run out 🤪 .. oh, and fave comedy moment was Gaz shouting “Pull, Pull, Pull” 🤣
What a great video. I was aware that there was an issue with DC in AC RCDs, but didn’t really understand why. Thanks for explaining the science, the impact and the circumstances under which it can happen so clearly. Top work gents 👍
That was the most interesting video I have seen for time, thank you so much for giving us such vital information/training on this subject. It will have now occurred to us all that RCD's are not the get out of jail fix rodeos can rely on
GDR Electrical thank so much. Joe is off the charts as far as world class skilled lecturers. We were so honoured for him to appear on this tiny channel.
Interesting and informative video guys, especially as EV home charging is becoming more popular now. It would be interesting to see how the A type RCD overcomes this issue. Managed to make it to the end of the video aswell👍
Great video Paul and Joe, super detail and explanation of the subject. As a former electrician and now a design engineer this is certainly making me more aware that specifying the most appropriate RCD is even more critical than ever especially in new domestic installations with PV and EV now more common and also when doing a condition report on an existing installation. I feel more clarity is required in BS 7671 Reg 531.3.3 and OSG of where different types of fault DC current can originate and which is the most appropriate type of RCD to install. You may have answered this in another video?
Great explanation. Except the using of term electromagnetic field in the core, there is a flux made by the two coil when everything is OK, the equal flux is zero when you have a fault the flax equal is not zero, causing EMF on the third coil that connect to electromagnet that trip the circuit
Great video very informative, currently doing my 2365 course (nothing has explained anything about this) and been working in the marine industry for years. We fit ground points on a boat which is used to ground the dc electronic equipment for interference generally used for the ac ground as well. Thank fully i haven't seen this fault yet but its good to know. Seems like we should only every fit at least type A
Thanks for this very useful video I have subscribed to your channel as your videos are very interesting informative and practical I love it thanks again.
I've just watched the first in the series of Ray Molony's 30 rules of lighting and interestingly he talks about lighting design and the joys of LED tape. LED lighting, of course, is rectified either in the lamp housing, or integrated fittings or very commonly via an external driver. So if you're installing lots of fancy recessed LED in multiple rooms within a property, I guess you should add that to the list, and I would imagine even more so than sockets with USB (although, I'm not a big fan of them) and give the lighting design, in terms of DC current, some serious consideration.
How many ma DC is harmful to an AC RCD 1ma , 2ma , 6ma , 20 ma ? Many EV chargers have 6ma DC leakage detection built in , is that enough to not saturate an AC RCD ?
The effects of DC wouldn't affect the tripping of an MCB though would it? So I guess you just have to be really careful of TT systems because a low impedance Zs would trip the MCB in the event of an earth fault. Fascinating presentation thanks for that.
Great explanation. Why is it that manufacturers are advising the RCD/RCBO should be disconnected from the load before testing, surely it is better if the device is tested while normal on load conditions are present. I'm also interested to hear that the DC is not always on the load side and therefore if my installation is near a railway line, solar farm or car charging station I should be looking at possibly type B RCD, but how as a hairy arsed spark am I supposed to test for this DC component.
Mark Holmes we should always utilise two tests. Neither in the regs🤦🏻♂️ one measure internal system leakage via a earth leakage clamp test in the tails. Also in addition where near a DC railway you can simply clamp onto the earth bonds or earth conductor to see DC on the system. On our Instagram page their is footage of measuring on a LV bond yet 1.6A of DC was present. Even a B type is not immune to that! Hence sometimes RCDs may not be effective but their selection may be reasonably practicable! Maybe!
The test is to confirm the characteristics of the RCD. By testing with other equipment present, there may already be leakage which will affect the test.
@@sdgelectronics exactly why we need to test with the load connected as anything that could affect the operating time of the RCD such as DC current or pulse from a SMPS or high frequency wave form from inverter supplies could mean the RCD is very slow or not operational at all.
@@markholmes4143 The manufacturer can only specify behaviour of how the RCD will work, not how it will work with uncontrolled equipment connected to it. Remember this is a test to confirm operation of the RCD not to test appliances. By the way, there should be minimal high frequency current or high frequency noise from SMPSUs otherwise we wouldn't be able to pass conducted emissions EMC testing.
@@sdgelectronics years ago before I knew about RCD's being disabled I would test with the load connected which failed then test with the load disconnected which would then pass. If I left the site with my certificate filled in to show everything was fine I am leaving the system in an unsafe condition. If the RCD is being affected by on site conditions I need to make the duty holder aware so either the RCD is changed for a more suitable type A,F,B,B+ or the piece of equipment causing the fault is disconnected. Electronic equipment may pass regulations when new but I have no way of knowing if components fail thus allowing DC current to leak or the AC sine wave to be altered back to the RCD. I can only do my test at that moment in time so can only report on my findings then. You obviously know a lot more about electronics than me, if you have time head over to the e5 group where a lot of electricians are trying to get there heads around the issue. Thanks
Excellent Video. But please could you explain how DC gets back into the neutral. Almost all PSU's in all equipment begin with an isolating transformer. So getting a pulsed "dc" signal back that way is not impossible but tricky. (Pulses only occurring on one side of the cycle). Beyond the PSU there is often a capacitor and very high resistance resistor to the chassis to prevent charges building and that would provide a very small current to earth. (In fact this used to be the cause of quite high earth currents in large office buildings.) Please could you direct me to, or give examples of how DC gets into the neutral?
Mark Horton sort we have not got time to check every comment on every video. And work full time, and create videos and go colleges and do all the voluntary stuff we do. We prioritise. More stuff on this will come. But we are doing the work to bring this to you so patience being a virtue comes to mind sir.
In normal equipment, probabilities are vanishingly small. Even in EVs there is galvanic isolation between the battery and the AC supply, the active PFC eliminates any pulsed DC effects so generally speaking, the only time this could occur is if there is a gross fault.
SDG Electronics thanks for the comment and it’s exciting stuff. Agree this should never normally happen. But it is with more and more poorly designed unregulated products it’s a real thing. We suggest we wait until amendment 2and see if the industry and manufacturers agree as they are declaring leakage from components and we suspect an AC ban in this or the next edition.
@@e5Group I mostly agree, especially on substandard products. The sceptic says there is a financial incentive too though to keep things being renewed and to bring new products to market.
How could you test for, or measure the dc current being produced in an ac circuit? I would imagine if you put a volt meter across the load connections of the Rcd it would read ac only??? Without an oscilloscope, how can the dc be measured on site?
Gareth Bradley megger have meters that will give readings.. even a clamp meter can help detect it. We found 1.6A flowing of DC on one install only a few weeks ago
Thank you Paul and Joe for a very informative video. The subject of DC effects on our 'general purpose' AC type RCD explained really well! Anything in the pipeline for A,F or B Types? p.s. Excellent work Gents :)👌
Next assignment: Find something that can save me from direct contact between phases or phase and neutral. Should I wear gloves and footwear all the time?
Thank you for this information well explained. Does the remanence remain in the core after the fault is removed? Therefore making the rcd permanently faulty?
Great video!, Question: How can I wired a RCD if when our power source is Line to Line(110VAC each) only and no Nuetral wire or Earth wire provided, The cooperative here in our place they only run 2 wire(line to line) only to there consumers and nothing else, Can I still use a RCD if not, any suggestion or remedy? Thanks
Adreen Ryan yes. But high voltages can damage sensitive electronics. This is more related to current not voltage and testers use very low current. Thanks for watching 👍
Guy's, I've been in the electrical industry for 45 years and I treat everyday as a school day. I'm a full member of the IET and have to say your explanation has given me a level of clarity on the issue I didn't have before I watched this. Fantastic video liked and subscribed.
Every day learning more and more.
you never stop learning, after 30 years i just learnt more , thanks guys
Love the simple demo of how rcd responds to dc
Very interesting Joe, excellent explanation
Very interesting thanks for taking the time to make this video
Well presented chaps!
Would be interesting to understand how a type A RCD operates and is able to overcome the effects of up to 6mA of smooth DC
They use individual current transducers on the phase and neutral. It's measured electronically instead. Sadly this puts the onus on some electronics to operate rather than the intrinsic behaviour we see with type AC
Great video, lived up to great expectations. Thanks. Tough to test or measure since DC currents may not always be there.
That's the reason type AC RCDs are banned here in Germany for new installations since 1984. The common type in residentials here is the type A RCD or RCBO. For electric vehicle chargers you should use type B, or as I did it for myself at home: Type A RCD and the wallbox charger got the DC protection inside.
Described nicely: "Persons don't test the RCDs often as they should". To my experience people are doing this almost never.
Marcel Germann exactly, thanks so much for watching and commenting 👍 more to come on the subject
Here in Romania, a lot of debate is rising here among electricians.
Type AC are most common, A are harder to find, B even harder :)
I think that a good grounding and, eventually, a second separate grounding must be there
Can't believe I haven't found this before today, for years I have been banging on about DC blinding RCDs.
That was the clearest most informative explanation of this subject well done guys
Guy Martin thanks you, more in progress to provide even greater clarity 👍
Excellent video. Thank you.
Cheers for this video chaps, I'm aware you guys have been working on getting this information out for some time.
Great video, packed with information.
Thanks again.
Daniel Casey more to come!
Paul and Joe very well done on the explanation great visuals.
Really interesting point about a 'bond' to PV and a damaged cell leading to a DC leak.
Great video! If only the schools was as detailed and great at explaining.
Really interesting, and excellent science teaching from Joe as always, and you’re wrong Joe, I always get to the end of your videos 🤓 .. you *and* JW, although I have occasionally repurposed JW when the sleeping pills 💊 run out 🤪 .. oh, and fave comedy moment was Gaz shouting “Pull, Pull, Pull” 🤣
This is a very good explanation of the problem surrounding AC type RCDs. This has really helped me understand the issue better.
What a great video. I was aware that there was an issue with DC in AC RCDs, but didn’t really understand why. Thanks for explaining the science, the impact and the circumstances under which it can happen so clearly. Top work gents 👍
Excellent Presentation...
That was the most interesting video I have seen for time, thank you so much for giving us such vital information/training on this subject. It will have now occurred to us all that RCD's are not the get out of jail fix rodeos can rely on
GDR Electrical thank so much. Joe is off the charts as far as world class skilled lecturers. We were so honoured for him to appear on this tiny channel.
Great video. Very much scientific.
Great content and presentation
Superb video,nice and clear chaps,excellent for learners and general sparks 👏👏
Excellent video, well explained. A major concern in TT systems.
Interesting and informative video guys, especially as EV home charging is becoming more popular now.
It would be interesting to see how the A type RCD overcomes this issue.
Managed to make it to the end of the video aswell👍
A type RCD dosen't overcomes this issue unless charger is equipped with RCD-DD
Great video Paul and Joe, super detail and explanation of the subject. As a former electrician and now a design engineer this is certainly making me more aware that specifying the most appropriate RCD is even more critical than ever especially in new domestic installations with PV and EV now more common and also when doing a condition report on an existing installation. I feel more clarity is required in BS 7671 Reg 531.3.3 and OSG of where different types of fault DC current can originate and which is the most appropriate type of RCD to install. You may have answered this in another video?
Great video, very interesting.
You kept me awake, very interesting and nicely explained 🤓
Brilliant demonstration well done lads
Great job guys I’m so glad you guys have got this content out here legends 👍
Brilliant video
Thank you guys very good explanation after happened to me last week when done rcd testing and not tripping
Great video guys.
Great explanation.
Except the using of term electromagnetic field in the core, there is a flux made by the two coil when everything is OK, the equal flux is zero when you have a fault the flax equal is not zero, causing EMF on the third coil that connect to electromagnet that trip the circuit
Great stuff chaps, explained brilliantly.
Great video guys :)
Great video keep up the good work,the more knowledge people have easier the job and ever day a school day
Well done - a first class explanation!
Great video very informative, currently doing my 2365 course (nothing has explained anything about this) and been working in the marine industry for years. We fit ground points on a boat which is used to ground the dc electronic equipment for interference generally used for the ac ground as well. Thank fully i haven't seen this fault yet but its good to know. Seems like we should only every fit at least type A
Just watching this a year after great content. Paul meenan iet should snap you up. Great video guys
Great video guys...I know understand this 👍🏼
Great video and content on a interesting topic that I know understand a lot better .
Great job explaining that Paul
Thanks for this very useful video I have subscribed to your channel as your videos are very interesting informative and practical I love it thanks again.
Subscribed
Best vdo sir
Great video, thank you. Is there a schematic available for the demonstration rig shown?
Rob Brown somewhere it fell out a few years ago. But pretty sure it’s somewhere in the shed. So yes
@@e5Group So where is it? :-)
Mark Horton email info@e5group.org.uk
Great video this one.
I've just watched the first in the series of Ray Molony's 30 rules of lighting and interestingly he talks about lighting design and the joys of LED tape. LED lighting, of course, is rectified either in the lamp housing, or integrated fittings or very commonly via an external driver.
So if you're installing lots of fancy recessed LED in multiple rooms within a property, I guess you should add that to the list, and I would imagine even more so than sockets with USB (although, I'm not a big fan of them) and give the lighting design, in terms of DC current, some serious consideration.
We told him years ago about this!
Can you do a video with a real circuit showing how DC gets into our AC 230 volt circuit ?
How many ma DC is harmful to an AC RCD 1ma , 2ma , 6ma , 20 ma ? Many EV chargers have 6ma DC leakage detection built in , is that enough to not saturate an AC RCD ?
The effects of DC wouldn't affect the tripping of an MCB though would it? So I guess you just have to be really careful of TT systems because a low impedance Zs would trip the MCB in the event of an earth fault.
Fascinating presentation thanks for that.
Great, information full video!
Could you guys guidelines us for proper supplying induction cooktop? What RCD type would be best here?
This video deals with smooth d.c.
I’m wondering if the same effects occur with pulsed d.c.?
Scary stuff
Guys' Thank You. But how do A type RCD's get round this direct current issue? Is there a video explaining this.
Great explanation. Why is it that manufacturers are advising the RCD/RCBO should be disconnected from the load before testing, surely it is better if the device is tested while normal on load conditions are present. I'm also interested to hear that the DC is not always on the load side and therefore if my installation is near a railway line, solar farm or car charging station I should be looking at possibly type B RCD, but how as a hairy arsed spark am I supposed to test for this DC component.
Mark Holmes we should always utilise two tests. Neither in the regs🤦🏻♂️ one measure internal system leakage via a earth leakage clamp test in the tails. Also in addition where near a DC railway you can simply clamp onto the earth bonds or earth conductor to see DC on the system. On our Instagram page their is footage of measuring on a LV bond yet 1.6A of DC was present. Even a B type is not immune to that! Hence sometimes RCDs may not be effective but their selection may be reasonably practicable! Maybe!
The test is to confirm the characteristics of the RCD. By testing with other equipment present, there may already be leakage which will affect the test.
@@sdgelectronics exactly why we need to test with the load connected as anything that could affect the operating time of the RCD such as DC current or pulse from a SMPS or high frequency wave form from inverter supplies could mean the RCD is very slow or not operational at all.
@@markholmes4143 The manufacturer can only specify behaviour of how the RCD will work, not how it will work with uncontrolled equipment connected to it. Remember this is a test to confirm operation of the RCD not to test appliances. By the way, there should be minimal high frequency current or high frequency noise from SMPSUs otherwise we wouldn't be able to pass conducted emissions EMC testing.
@@sdgelectronics years ago before I knew about RCD's being disabled I would test with the load connected which failed then test with the load disconnected which would then pass. If I left the site with my certificate filled in to show everything was fine I am leaving the system in an unsafe condition. If the RCD is being affected by on site conditions I need to make the duty holder aware so either the RCD is changed for a more suitable type A,F,B,B+ or the piece of equipment causing the fault is disconnected. Electronic equipment may pass regulations when new but I have no way of knowing if components fail thus allowing DC current to leak or the AC sine wave to be altered back to the RCD. I can only do my test at that moment in time so can only report on my findings then. You obviously know a lot more about electronics than me, if you have time head over to the e5 group where a lot of electricians are trying to get there heads around the issue. Thanks
Excellent Video. But please could you explain how DC gets back into the neutral. Almost all PSU's in all equipment begin with an isolating transformer. So getting a pulsed "dc" signal back that way is not impossible but tricky. (Pulses only occurring on one side of the cycle). Beyond the PSU there is often a capacitor and very high resistance resistor to the chassis to prevent charges building and that would provide a very small current to earth. (In fact this used to be the cause of quite high earth currents in large office buildings.)
Please could you direct me to, or give examples of how DC gets into the neutral?
Over a month and no reply. I must confess I am a bit disappointed.
Mark Horton sort we have not got time to check every comment on every video. And work full time, and create videos and go colleges and do all the voluntary stuff we do. We prioritise. More stuff on this will come. But we are doing the work to bring this to you so patience being a virtue comes to mind sir.
In normal equipment, probabilities are vanishingly small. Even in EVs there is galvanic isolation between the battery and the AC supply, the active PFC eliminates any pulsed DC effects so generally speaking, the only time this could occur is if there is a gross fault.
SDG Electronics thanks for the comment and it’s exciting stuff. Agree this should never normally happen. But it is with more and more poorly designed unregulated products it’s a real thing. We suggest we wait until amendment 2and see if the industry and manufacturers agree as they are declaring leakage from components and we suspect an AC ban in this or the next edition.
@@e5Group I mostly agree, especially on substandard products. The sceptic says there is a financial incentive too though to keep things being renewed and to bring new products to market.
Remanence ⚠️
How could you test for, or measure the dc current being produced in an ac circuit? I would imagine if you put a volt meter across the load connections of the Rcd it would read ac only???
Without an oscilloscope, how can the dc be measured on site?
Gareth Bradley megger have meters that will give readings.. even a clamp meter can help detect it. We found 1.6A flowing of DC on one install only a few weeks ago
Gareth Bradley it’s should also only appear on the earth or neutral side of the system. 👍 makes you think!
Thank you Paul and Joe for a very informative video. The subject of DC effects on our 'general purpose' AC type RCD explained really well! Anything in the pipeline for A,F or B Types? p.s. Excellent work Gents :)👌
Shaun Sparky yes, Paul’s working on a. Sit down standards review
Next assignment: Find something that can save me from direct contact between phases or phase and neutral. Should I wear gloves and footwear all the time?
Thank you for this information well explained. Does the remanence remain in the core after the fault is removed? Therefore making the rcd permanently faulty?
will disappear after time or when the dc fault is removed
happy 2921 to u and your team...can insulation resistance tells u if there is DC volt leakage in a circuit
So does an A type trip when it detects dc current or do they just work as they should over 30ma on ac current ? Confused.com
Where the link gone for the cpd? Thanks
It’s ok.. my fault.. I’m on the wrong video clip 🤦🏻♂️
Great video!, Question: How can I wired a RCD if when our power source is Line to Line(110VAC each) only and no Nuetral wire or Earth wire provided, The cooperative here in our place they only run 2 wire(line to line) only to there consumers and nothing else, Can I still use a RCD if not, any suggestion or remedy? Thanks
マグプザオリカルド if it is 55v CTE YOU CAN GET A BESPOKE RCD FOR 110v ask Crabtree for a Railway 110v special
dont you test instllation with dc when testing megger tester 250v 500v DC
Adreen Ryan yes. But high voltages can damage sensitive electronics. This is more related to current not voltage and testers use very low current. Thanks for watching 👍
The POMs aren't as dumb as they look