Should we just stop using Type AC RCDs?

With the re-write of a Section of the Wiring Regulation there is a lot of talk about AC RCDs and if they really are any use any more?
Yet the Wiring Regulations says that they are suitable for general use?
PLEASE REMEMBER THAT THESE OPINIONS ARE MY OWN AND NOT THAT OF ANY ORGANISATION/GROUP I AM AFFILIATED WITH.
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[@bigclivedotcom]

I've often pondered the fact that most municipal Xmas lights use rectified but unsmoothed DC for the LED rope light and strings. The majority of installers probably use the cheapest RCD they can get, if any. There's an unfortunate tend towards event companies getting their finger into the pie and using low wage casual labour to handle, erect and maintain municipal Xmas displays now, and that is potentially resulting in more scuffed and damaged wiring on what are effectively aluminium frames with mains wiring lashed tightly over most of their surface. Exciting.

[@SparkyNinja]

Indeed. I don't think I've ever seen it referenced in the BS7909 standards or similar. It's early days but we are finding evidence of other European countries now where AC RCDs are not allowed in the 'ordinary person' environment. They're being killed off.. but not here yet. Love your channel btw.

[@daviddews5896]

listening to this has being very interesting. my question is what lighting types may induce this dc voltage … im taking it dc possibly selv led laps etc what about 230v gu10 led laps due to the electronics inside them ?

[@charliechimples]

Hi. Just passed 18th edition today with a score of 91%. Needless to say your vids on the subject was the main reason I passed. I watched them through twice and the one on the exam itself. Thanks a lot. 🐵🐵

[@peterpage7322]

Great video, thank you. One question, can you mix ac and a type rcd’s in the same consumer unit? The reason I ask is I was asked to fit a type a rcd downstream from a type ac rcd in a domestic garage consumer unit to enable a ev charger to be fitted. When I did this the fluorescent lights stopped working until I changed the rcd back to a ac type? The lighting circuit was also downstream from the a type rcd but next to the a type rcd. Any help would be appreciated.

[@spinlondon]

One of my concerns, is would d.c. leakage on one circuit affect the operation of RCBOs on other circuits in an installation where each circuit is protected by an RCBO?

[@J0nny61]

Most likely Spin

[@gd-bq7em]

Hi Ive got a question for you. If I was going to change a cooker outlet plate the back of an electric oven that is non rcd protected to a normal single socket for a 13 amp plug would this socket then need to be rcd protected. Or is it just classed as changing like for like and would be fine non rcd protected Thank you

[@m1kejay]

It's not changing like for like, it would need to be RCD protected.

[@MrBradleya16]

Hi would you be interested in doing a 2357-44 electrical nvq guide? Im doing mine and currently findimg it very difficult

[@amirnaz6691]

Hi Mr Ninja Could you please kindly help me how to carry out time delay 3 phase RCD test using multifunctional Megger tester Thanks

[@jordanharrison7310]

Question. How do I calculate the breaker size for supplying a garage? I’ve ran a 6.0mm 3 core swa only around 5 metres

[@SparkyNinja]

Ib

[@jamiekent1970]

Hi Sparky Ninja I understand that type A is limited to 6ma and type F has a 11ma limit how would one determine these values for a given circuit. As in would you have to calculate the residual DC In selection the correct device, any handy formulas that can be applied would be helpful Cheers

[@petrol_burner]

Very interesting to see how DC current affects the RCD. I see a need for a lot of RCD’s and RCBO’s needing changed, in industry now !

[@irfp460]

As soon as you have a VFD somewhere you can only use a Type B RCD.

[@J0nny61]

Hi, everyone, I've been a member of the IET for 16 years, with 44 years experience in the industry and got lucky enough to have a couple of days last month with someone that writes codes of practice and sits on the JPEL committee. Just to be sure, I'm not an expert in this subject but have managed to gain a few facts from several respected professionals. I was a bit of a sceptic about the new requirements for type A and B RCD's and then further scepticism about upstream devices being blinded by DC faults. When it was explained in detail it became clearer. This is how I think it goes. If you have a slight DC leakage or high frequency AC leakage downstream of a type AC RCD, which is not enough to trip the type A or B downstream and then you get a full AC earth fault on the circuit. The upstream type AC RCD will not trip as the minimal DC or High Frequency AC leakage does not allow it to operate. Does that make sense? Great video and I think we have the same conclusion.

[@GSHElectrical]

Fantastic Mr Ninja 👍

[@teamsjonline]

Just came across this. Really informative and thought provoking. Wonder what this could mean for future EICRs ?

[@m0wao690]

Yep; I used an Type B for my home made EVSE :)

[@AndrewCook7]

Excellent theory. Brilliantly explained

[@jamiekent1970]

Hello Sparky ninja Is this rewrite to BS7671 2018 a free download or something you have to pay for on top of the huge cost of the current regs book??

[@SparkyNinja]

Hi Jamie, The 18th edition was the re-write, I apologise if I didn't make that clear. Regards SNinja

[@jamiekent1970]

SparkyNinja Ok thanks

[@PhilipHudnott]

Wholesalers/suppliers need to publish more information to help with selection. I have been trying to quote for a new cu with rcbo’s, the issue I have had over the weekend is that many of the websites do not specify the rcd component of the rcbo’s on their sites which makes it difficult to find what I need. I spoke to one supplier who said “it’s a type B rcbo” and when I questioned wether this was the mcb or rcd component I think I lost him.

[@joshcook823]

Hi there, your videos are extremely informative. Could you please consider making a video on three phase unbalanced voltage drops, ie how to calculate the drop in the neutral

[@SparkyNinja]

Will do.

[@markholmes4143]

Very good explanation, I feel our industry bodies have been asleep on the job and even now they are not fully aware of the implications. Many customers are going to be pissed off when a spark who does know about this issue refuses to alter a circuit protected by a type AC RCD and then goes on to say the manufacturer of your consumer unit does not make a compatible type A RCD as an upgrade (Schneider) so either the whole unit will have to be replaced or some sort of crap looking add on will be done. How long before type A is not suitable and we need to fit type F or B as general purpose devices.

[@J0nny61]

I suppose the other issue is BS7671 only requires an AC test.

[@PJB71]

Hi sparkyninja, I have a question which maybe you could cover in a video. Can you use single pole rcbo's in a domestic situation? The reason i'm asking is because it is one topic that seems to get different answers no matter what spark you talk to. I was always taught the rcbo must be D.P, but after looking carefully at the regs it suggests to me that it would be fine to use single pole rcbo's & use the main D.P switch as isolation.

[@Elifius]

Are there A type rcbo 16A and 6A

[@bumbles1584]

Both wylex and hager have type a rcbos cant speak of other brands as we don't use them very often

[@wallbouncer9655]

Absolutely amazing video 👍🏻

[@PJB71]

Hi sparky ninja, love the videos. I have a question regarding the type of RCD’s during a EICR in a domestic situation. Most domestic situations will have type AC RCD’s or no RCDs at all. What type of coding would you give to that installation, most have washing machines, most have some form of LED lighting. If it was empty property & there were no appliances at all. I have asked around, including the technical helpline & no one can really answer me. In theory most domestic installations could be potentially dangerous if using AC RCD’s. I’m I correct or interpreting this incorrectly. Thanks for any advice. I would also like to add, that I have just worked in a new build property & guess what type of RCD’s are in there AC.

[@SparkyNinja]

Hi Patrick. This is something that we are getting more and more information on as we research it. Do be sure to watch the upcoming videos on the e5 KZbin channel which will give you even more information when we put them up. If I was in a domestic EICR this morning, I would be assessing for the quantity of electrical equipment that may create DC residual currents. If I identify some then there is definitely a potential for a C3 observation of 'improvement recommended'. If I was to identify some leakage of DC origin, then I may escalate the code. This is all in it's infancy as the industry hasn't prepared us for this information - but we will be providing more content and support to everyone through our channels on this very soon.

[@PJB71]

SparkyNinja, it’s just as well there are exceptional people like yourself, giving their time & expertise to the average jobbing spark. Thank you.

[@ohmslaw3182]

Something I don't understand: We are talking about an RCD, therefore the 'residual' current. In general the principle of operation of an RCD is a cutout that is operated by an imbalance on the supply lines and NOT a cutout operated by the fault current. That is the current difference between Line and Neutral on the supply causes the cutout to operate, not the earth current. Therefore if your supply is AC only without a DC component, then the residual current will be AC, or at least pulsed in some fashion, and not DC, because the supply always crosses zero. I will have to re-watch.

[@SparkyNinja]

It is a tough topic to explain. The problem is that whilst the DC residual current does in fact not leak 'through the RCD' the proportion of imbalance with the AC current that is montored by the RCD is again only comparable with the DC residual current. Therefore if there is only the DC residual current present this will biase the AC RCD to only identify residual current on one side of the AC waveform - hence the shift along the 'H' axis.

[@ohmslaw3182]

So really the issue is not with the type of loads, it's a concern with power companies supplying me with a DC biased supply?

[@ohmslaw3182]

I have watched it again. At 5:12, where you say a failure in a device will be a 'DC residual current'. I think the issue is that this kind of failure will produce a DC 'fault current' that is current that flows from Live, is rectified and then flows to earth and the fault current is the amount of current in the earth conductor. Residual current is different, this is the current difference between Live and Neutral which is still AC.

[@SparkyNinja]

@@ohmslaw3182 yes but if the leakage current is of DC nature, then the RCD will only be able to identify the imbalance when the supply AC matches the leakage current.. which will only be on one side of the waveform.

[@muzikman2008]

Interesting.. Great insight thanks.

[@mendicant1981]

Are you making videos elsewhere now?

[@SparkyNinja]

Hiya, No, I've taken part in other videos but there will be videos returning here in the next few weeks.

[@jamanemaraashollington8760]

Hi sparky. Do you do any form of private tuition or training? The reason i ask is I have been self employed 5 years and I have no one around for impartial advice and I feel that I’m being left behind in the industry. I am currently going through your brilliant 18th edition uploads but I find my self in situations at work where I’m thinking what is compliant here. I strive to be as compliant as I can but sometimes I find myself not being able to find the information I need to make my installations better than what is in the regs.Id love a form of question and answer scenario. I have no idea how to contact you apart from here but I’d happily pay for someone like you to help me improve my standards and knowledge. I’d put my email address but it will probably get spammed.

[@SparkyNinja]

Hi there. I can be reached on Twitter, Instagram, Facebook and I also run a discord server.. are any of those available for you? You can connect with me and then I can try to help you. 👍

[@piotrliszka8481]

Hi there. Correct me If i am wrong, but I don't think you are right about AC RCD. As far as I am concern, as long as they supply from mains (not from inverters, photovoltaic etc) they ,,don't care,, of what are they supplying- even on the event of faut of equipment that rectifying ac to dc such as washing machine with dc motor, power supply, etc, those devices still pulling AC From mains, and if there is a fault, then AC RCD should detect that with no problem. I am agree that they will not be good if you use them to protect, when they are supplied from different source than mains. Regards.

[@SparkyNinja]

Hi and thanks for your comment. The issue here is the nature of the residual current. If it is DC in mature then it will affect the operating characteristics of the AC type device. Thanks.

[@matthewdale956]

Anyone else’s eyes start glazing over when the Hysterisis examples started 🥴

[@SparkyNinja]

That's why there is a pause button. You can return later when loaded with alcohol are other substances where it can start making sense.

[@matthewdale956]

SparkyNinja I’ll try that mate 😂

[@HeathenGeek]

'Electrium Podcasts are non-statutory. They may, however, be used in a court of law in evidence to claim compliance with a statutory requirement?'

[@sanchezlatchman906]

Great video thanks. Sound is a bit low for my phone, I struggle to hear you. 👍

[@alexcantley9137]

Come on manufacturers help us out if they can identify a problem and solve it in the background by getting rid of type AC RCDs why don't they ??? £££££ instead they hide behind behind well THEY should know imagine trying to explain this to a customer it's hard enough sometimes trying to get them to pay for smoke detectors nevermind showing them hysteresis loops most of them still wouldn't give a fxxk lol

[@slobodandokuzovski373]

This is all upside down approach.DC pollution in AC systems is the problem not the AC type RCD. If regulatory bodies was so stupid to allow non standard DC pollutants as devices how they think will sort out now any problem rising with DC pollution of AC circuit.With alphabet of RCD types personalised for each pollutant character and alphabet of RCD test instruments for alphabet of types of RCDs...If the pollution affects only the usefulness of protective devices maybe I can understand changes.But no there is more to DC pollution in AC systems damaging way more components of AC distribution than the eye can see and render useless electrical devices affected by some weird resultant harmonic waves. Obviously these changes were done without wider input of the electrical engineering field. This can happen only if people involved are narrowly focused in personal protection disregarding wider implications of pollution of AC systems.

[@kkyriacos2427]

Well none of this makes sense of course. BECAUSE: 1) The DC current that the type A will tolerate before saturation is 6mA. This is quite small. So in effect type A will behave the same as type AC when the 6mA is exceeded !! 2) Most of the demonstrations done to show the impact of DC offset on AC RCD operation is using either 50mA or 250 mA of DC. I bet you any money type A will not operate under those test conditions either since by definition it is rated to tolerate only 6mA of DC. 3) How do the current AC RCD behave with 6mA of DC?? I have seen no one test this out !! If for example a good brand of AC RCD of today eg MK can tolerate 6mA of DC then it is no worse than a type A. So a lot of talk but no real data to support the new regs.