The Complete Guide To RCDs - Residual Current Devices

Most circuits within a modern electrical installation are protected by an RCD or Residual Current Device. RCDs offer protection against electrical faults and electric shock. However, as electrical installations and connected appliances become more complicated, this places additional requirements on the designer to ensure the RCDs are matched and offer the correct levels of protection. In this free accredited CPD training module, we explore using RCDs as defined in BS7671 UK wiring regulations.

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00:00 Introduction to RCDs
01;20 What protection do RCDs provide?
03:40 How do RCDs work?
08:40 DC leakage currents & non-linear electrical loads
12:30 Different types of RCD
13:00 Type AC - RCD
14:10 Type A - RCD
15:30 Type F - RCD
17:10 Type B - RCD
18:40 Installing the correct type of RCD
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If you'd like to record watching this video as part of your continuing professional development (CPD)

CPD is a requirement for membership of competent person schemes operated by NICEIC and NAPIT
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#electricaltrainingvideos #electricians

[kelvingomersall]

I will genuinely never understand why the education sector looks down on YT and lecturers using such tools. You guys are the pinnacle of electrical kmowledge (more so than some of the plebs that work with the IET). Forever thankful for you guys and your clear, precise explanations. Exceptional work as always.

[gibbodive]

These high quality, informative, understandable presentations are very often hugely superior to those we receive at training centres.
I especially appreciate the personable presentation skills of Joe who covers the theory, where it relates to 7671 and what it means in practice.
Thank you.

[martinnewbery]

What an exceedingly interesting video. It suprises me that there is no obligation on the part of appliance makers to block any DC effects that may reduce RCD efficiency. Martin.

[nigelconnor]

An exceptional tutorial. Thanks Joe for your succinct and clear explanation. It was a great help when I was recently doing my 2391 and I sent it on to my classmates. The tutor also seen it and thought it was great. You and the rest of the team all have done a great job and keep up the good work. Thanks again.

[ridetheion]

This explains something I had a totally thought wrong. 20+ years ago I worked at a hospital as a researcher. We had labeled socket that it was forbidden to plug in a computer. I assumed the non-labeled sockets were behind a better UPS or something to protect the computers. I would have never thought the fault protection could be compromised by the PSU 😲
Thanks 🤯

[fqlynx]

Loving this type of content, you'll make a sparky out of me in no time.

[champagnesupernova]

Cheers for this, I never knew how to identify the different types of RCD's, and usually took a guess when doing EICR's.

[tonyknight]

Brilliantly well explained, thank you !

As I see it the problem lies with 'normal' 13A plug connected devices being infinitely able to transport increasingly complex devices around. Such devices really need to be permanently hard wired and given their own RCD protection of a type befitting their complexity and ability to inject dc components into the ac line.

[kankoeadamahhemazroyao.]

is that oh joe? . Thanks for the video, very simple and straight on point

[PardoeElectrical]

Great video, I did the CPD and didn't do too badly, in a domestic electrical installation majority of circuits would be suited to type A and a kitchen ring/radial circuit the type F

I did a little product search online, seems hager sells type F

We install fusebox and they don't have anything other than type A at this moment in time.

[eddieking]

I can not fathom why the latest edition of BS7671 has not banned type AC outright. It would remove potential confusion over which type of RCD to install. Here in Germany type AC has been banned in new installations for decades.

[eded]

thank you for the clear explaining, now makes sense to me, as why some RCds pass tests but still not tripping on over 30mA actuall leakage !

[martinkelbel]

Very informative video. The problem I see is that many online shops are confusing "type B" with "B curve"

[goldeagleengineering]

please do more and more of these educational programs. Honestly, I would pay for your programs. Have you got a patreon or funding pages ? Seriously, amazing content.

[Dog-whisperer]

Great video Joe as always, excellent explanation, but in a video you did earlier last year the guy who was with you gave a live example of how DC could effect Type AC RCDs, it showed very clearly that AC type will trip but it could take as long as 190ms or more and that would mean some poor sod won’t be having a good day . Also you didn’t mention anything about RCD uplift ? .
Great video as always mate 👍❤️

[christastic]

Really good presentation, very informative .

[johngray]

Absolutely brilliant explanation. Thank you.

[AviKhali]

Well explained vid. Thank you for your efforts and hardwork

[Mike_]

Brilliant and very informative here and Joe and the team have obviously done their homework for this but you can see on the horizon the next edition of the Regulations requiring tighter circuit disconnect times and more discrimination of loads on individual circuits coming?

[GEJD]

It’s a good video, but I think you missed a vital piece of understanding as to why an RCD is set at 30mA; because a current exceeding 30mA is likely to be fatal unless it is interrupted in a very short time, followed by the need to occasionally scale RCD’s upstream (which you did cover) but then to ensure no circuits can ever come into human contact unless there is a 30mA RCD in line. Some people may be tempted to fit a 100 or 300mA RCD if they don’t understand why the 30mA protection level is required. Actually 7-8mA is often fatal for some people.