What's the difference between an RCD and an RCBO? - Circuit protection.

What is the difference between a residual current device and an RCBO
In this electricians' Q&A, Joe Robinson explores the topic by looking at how the devices work and what standards are used to define them.
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❌ This content on this channel is for electrical professionals.❌ ==================================
📹 Presented by
Joe Robinson - Technical Editor eFIXX
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#efixx #cpd #circuitprotection

[@G4GJL]

Clearly and concisely explained. Thank you Joe.

[@brianwarde2088]

I just started a new job doing panel building. Your videos help me a lot.

[@SJLEsperance]

As a student surveyor this was excellent watch. Thanks

[@seanphillips24]

Very clear. Thank you!

[@raquelsapalaran2907]

great video tutorial,very informative. thank you for sharing your knowledge.❤️

[@vinaybeeharry3893]

Very good explanation indeed.Thank you sir !

[@brianwood5220]

well explained Joe.Thanks

[@khalidsr1]

Thank you eng joe 4 your great information, really needed to add it to my knowledge.👍😇 Best wishes to u . Khalid RAC tech.

[@johnwalsh7470]

Great clarity

[@eddprice4571]

Great video Joe 👍 thanks

[@efixx]

💕🦾💕

[@bmonck5110]

very very clear. thanks a lot

[@khalidrash5814]

Hello sir, Should the outdoor service switch be greater or smaller than the main breaker in the consumer unit? I'll be so grateful if you would send me back. Thank you, Khalid

[@brianwarde2088]

Thanks

[@lindambele5489]

How do u claim the cert?

[@OldLordSpeedy]

This I like at the UK regulations: The RCCB/RCBO use only one space place. In Germany all 2pol (L+N) RCCB/RCBO are two space wide, mean need special power bar with L+N. Here use mostly L1+L2+L3+L1 aso. or same L as in UK. We say RCD to a RCCB here. A normal device is a MCB.

[@ratsalive]

Nice 👌

[@efixx]

👍

[@cag9284]

What link below??

[@onetrueone]

I still did not quite grasp how the RCBO works, does it function as a normal breaker on top of being able to detect a short circuit?

[@sajad459]

Hi joe, do you have any idea why BS7671 forbids installing RCD's in a TNC system? I am aware that this is not a perfect protection, but in old buildings which don't have any earthing system, the presence of an RCD would be better than not using it.

[@efixx]

Hm, that is a really good question, I'll look into it. 😊

[@marmalizer2010]

TNC systems have a PEN conductor (basically a neutral & earth combined or "protection neutral lin") so earth faults would be undetected as there is no inbalance, so pointless really.

[@sajad459]

@@marmalizer2010 In case of fault, they will not trip , but when someone touches the exposed conductive parts, that would be a life saver!

[@mrbugenhagen3364]

Well you can in Sweden if you do it right. Take the incoming PEN and attach it to the earth rail. Then run an earth wire from the earth rail to the RCD and then from the other side of the RCD a neutral wire to the neutral rail. Then you will have the neutral separated from the earth.

[@markhardacre1]

Where’s the link?

[@johnwaby4321]

Nice one .. have seen only the rcd fitted to some circuits 😯😯

[@efixx]

😮

[@mb-electricalservices]

Did an EICR at a property not long ago with an RCD fed direct from Henley blocks off the meter. The RCD fed a garage which was wired in T&E partially buried. Scary stuff.

[@ianyanto123]

@@mb-electricalservices I came across something similar, rcd fed from Henley blocks feeding a 2 way consumer unit powering 2 ovens. The argument was that the mcbs provided overcurrent protection with the rcd covering fault. Like an extended version of a split load board? Thoughts?

[@johnburns4017]

@@mb-electricalservices An RCD can act as a main switch, it is DP. If the T&E is properly in conduit, then all is fine.

[@andytap560]

@@johnburns4017 i was going to say this,not unusual to have rcd main switch

[@andrewcarson9068]

is its operation based on Kirchhoff Current Law?

[@deang5622]

Not quite. Kirchoff's current law says the sum of currents entering a junction or node equals the sum of currents exiting it. Or alternatively, Σiₙ = 0 Where the direction of the currents is assigned a positive or negative value. The way an RCD works is by detecting a difference between line and neutral currents, going to a load. In normal operation these two currents should be identical in magnitude. Current into the load must be equal to the current out from it under normal operation. So the RCD is trying to detect the situation where these currents are not the same magnitude. And the way they do it, is by creating two opposing magnetic fields which cancel each other out, in that they are equal in magnitude but opposite in direction. And the easy way to do that is to use two solenoids in order to create the magnetic fields and put those those solenoids on to a ferromagnetic core to enable good conduction of the magnetic field between them and the sense coil. As someone else pointed out, quite correctly, the diagram in the video is technically incorrect with regards to one of the coil windings - it doesn't matter which one, but they are both wound the same way on the ferromagnetic ring, and one needs to be wound in the opposite direction for the RCD to work properly. The third coil is a sense coil which will detect the presence of the un-fully cancelled-out magnetic field where the line and neutral currents are not equal. So the operation of the RCD is really based on the interaction of two magnetic fields, one from the line current, and the other from the neutral current.

[@SniperZoz]

Hey - hobbyist here with a good understanding of electricity. Will soon be undertaking a home renovation which will include a (professionally installed) new consumer unit etc. Looking at RCBO but noticed that most are single pole rather than dual (like an RCCD) - i.e. an earth to neutral short would trigger the RCBO disconnecting phase but not neutral. Isn't this less than ideal?

[@piratedprivacy9052]

How you tell thats a 1P RCBO ?? 1P +N for RCBO does not necessarily mean that it will not disconnect Neutral...

[@SniperZoz]

@@piratedprivacy9052 based on research most don’t! To be fair some do and I’m not sure about the ones in the video, but fact remains that most common RCBOs are SP

[@djgrof1]

Is it possible to use one RCD(or RCBO) with one AFDD to secure multiple circuits (6 for example) that are protected with MCBs? Im bit confused with installing AFDD, because its expensive to use on every circuit, but if can use 2 or 3 per board instead of 15 that would be great.. Eu-installation

[@piratedprivacy9052]

1 nos of 2P-RCBO can be assigned to protect a group of say 6 MCB. But 1 nos of AFDD is not intended to 'monitor' a bunch of final circuits... As mentioned a unit of AFDD is solely for each/one final circuit.

[@deang5622]

You do not have to use an AFDD on every circuit. You identify which you consider to be the circuits of highest risk where the maximum level of risk reduction occurs by installing one. Now, there are scenarios where AFDDs must be installed, and these are scenarios which are considered to be higher risk and where it is considered the higher cost of using AFDDs is justified. Check the BS7671 for details of these scenarios. Typically, but not limited to, it's HMO, student accommodations, care/nursing homes, and blocks of flats higher than a certain number of floors.

[@jimgeelan5949]

No the front of them it say test regularly, sparks installs, tests, and fills out the forms that’s the last time that ever gets looked at until something goes wrong, real life. 😃

[@piratedprivacy9052]

Until/when there's a fault, it'll Test Itself 🤣🤣

[@sonnyfung5135]

Where is the FE wire (white) of the RCBO?

[@thechampvishnu1518]

How to identify a rcbo. Please someone explain

[@efixx]

Look for the test button

[@A1theAPEX]

Same electrical systems different county different ways of doing it 🇺🇸 🇬🇧 very interesting 🤔

[@sonnyfung5135]

What about earth leakage circuit breaker? Very confusing.

[@9plusinstalaciones]

Impact Driver

[@efixx]

Not on my boards! 😂

[@9plusinstalaciones]

@@efixx 🤣🤣🥳

[@akhtaralimalik989]

Where is this information that you said “ it’s down below for us to click “ ? I don’t see any ! Davis Malik

[@efixx]

It's in the video description. 😊

[@mikeselectricstuff]

The transformer winding polarity on that drawing is wrong

[@efixx]

Thanks for the heads up, it's illustrative really.

[@TheFool2cool]

Could you elaborate Mike on which bit is wrong?

[@jaymercy224]

In this diagram, the magnetic fields do not cancel each other out. Either the L or N winding should be wound in the other direction. And instead of the magnetic field jumping through the air as shown here, it travels all the way to the core. (2:05). Otherwise, the presentation is good and illustrative.

[@georgiosyiannakou5537]

@@jaymercy224 Good observation!

[@deang5622]

Absolutely right...but technically not a transformer..it's two solenoids on a ferromagnetic ring, with a sense coil.

[@michaelkhan3628]

So RCCB is a RCD just another name?

[@computeraddic675]

Why havent the engish speaking people a proper name for things??We call them the Group breaker(translated off course) and Alamat.And the box with the group breakers a group breakers box!Almost ever situated right after the frontdoor in a special cupboard with a normal door.Gas and water will also be there.Heated and cold.And of course the Earhtleak breaker.

[@gameclan5831]

These rcbo devices create extremely high levels of dirty electricity, in turn creates fibromyalgia increases to the suicide rate, hopefully these devices are phased out in the future

[@ChasinOneTwelve]

Wth how? Could you explain?

[@Ste2023]

Wtf ....where did you read that

[@Ste2023]

Wtf ...