Protecting lighting circuit with RCD?

Andy From Sligo · 23-02-2017 05:32PM #1

Hello - is it normal regulations not to have the lighting circuit protected by RCD (RCB) for resiential ?

We have 1 RCD it the consumer box (Top Left) and in the storm last night at 4am the RCD Tripped (for some reason) and all sockets were off in the house.. but the ceiling lights were on .

In my other houses we have rented there was only 1 RCD in the consumer box but if that tripped the lights went out as well (ie the RCD was just after the mains switch in the consumer box and it protected the lights and sockets)

Isnt it just as important to have the lights and lightswitches protected by an RCD so that if you accidentally touched a lightswitch with wet hands (yes I know you shouldn't) or the light switch was cracked or damaged and you came into live parts of the switch or if water dripped down light pendant fitting or lightswitch that it would trip an RCD ?

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meercat · 23-02-2017 06:21PM

The current regulations state that only bathroom lights and lights not fitted to the house structure be rcd protected
These regulations were probably not in place when your installation was constructed as they are relatively new.

23-02-2017 06:42PM

Andy From Sligo wrote: »

Hello - is it normal regulations not to have the lighting circuit protected by RCD (RCB) for resiential ?

As per the above post lights in a domestic installation are not normally protected by an RCD (apart from bathroom lights). In my opinion protecting lights with an RCD increases the risk of injury (even in a bathroom). This is due to the risk of tripping in the dark following nuisance tripping of the RCD coupled with the low risk of shock from lighting circuits.

We have 1 RCD it the consumer box (Top Left) and in the storm last night at 4am the RCD Tripped (for some reason) and all sockets were off in the house.. but the ceiling lights were on .

Very normal.

Andy From Sligo · 23-02-2017 06:55PM

meercat wrote: »

The current regulations state that only bathroom lights and lights not fitted to the house structure be rcd protected
These regulations were probably not in place when your installation was constructed as they are relatively new.

ah right - 2008 the house was built...

Andy From Sligo · 23-02-2017 10:50PM

Any Idea why the RCD Sockets tripped in the middle of the storm last night? - I would have thought to trip there would have had to be leakage to earth from live or neutral to trip it - no sockets would have got wet, no lightening there wasnt. there was a blip of a power cut for a second but power cuts dont normally trip an RCD in the CU do they?

alan4cult · 24-02-2017 01:59AM

Andy From Sligo wrote: »

Any Idea why the RCD Sockets tripped in the middle of the storm last night? - I would have thought to trip there would have had to be leakage to earth from live or neutral to trip it - no sockets would have got wet, no lightening there wasnt. there was a blip of a power cut for a second but power cuts dont normally trip an RCD in the CU do they?

Either outside power of some sort like, LED lights or any garden lights running on same RCD?

Otherwise do you have an aerial or dish directly connected to your TV? Sometimes there is leakage there that's enough to trip RCD.

Andy From Sligo · 24-02-2017 03:20PM

alan4cult wrote: »

Either outside power of some sort like, LED lights or any garden lights running on same RCD?

Otherwise do you have an aerial or dish directly connected to your TV? Sometimes there is leakage there that's enough to trip RCD.

thanks for that, all outdoor lights above the doors on lighting circuit, which in turn isnt protected by RCD (maybe they should be , I still dont like the idea of lighting not being protected by RCD, especially if they are outside and getting damp)

But yeah, a Sky satellite dish is out there surely

alan4cult · 24-02-2017 06:48PM

Andy From Sligo wrote: »

thanks for that, all outdoor lights above the doors on lighting circuit, which in turn isnt protected by RCD (maybe they should be , I still dont like the idea of lighting not being protected by RCD, especially if they are outside and getting damp)

But yeah, a Sky satellite dish is out there surely

Hi Andy,

Usually the dish is not the problem. because it's isolated by the Sky box transformer. However, what can trip RCDs is if you have an old aerial on the roof for old analog signal and a booster was used from the attic, then static on the aerial can cause a live neutral imbalance which can either show where the booster is plugged in or where the TV is plugged in.

It will be difficult to find a fault like this, if it starts tripping again I'd call an electrician to do some resistance tests.

Andy From Sligo · 24-02-2017 09:49PM

Getting a little bit obsessed now i know lights are not protected by RCD (ELCB) - whats been seen cannot be seen

What if I (or member of family) touch a faulty light switch, What if I am changing light bulb in ceiling and touch live (yep I know you should turn off breaker or mains switch at consumer box) - or if a damp light switch - I want an RCD to trip I dont want to just rely on an MCB which will only work when it directly short circuits.

So, what would be the best way to go? -

Theres a B10 (10amp MCB breaker) for downstairs lights, then theres a B10 for upstairs lights - would you whip them out and replace with 2 10a RCBO's ? or would you link them up to the existing RCD in the CU that protects the socket or would you get a RCD and protect the B10's (so I have 2 RCD's in the box, 1 protecting the sockets and seperate RCD protecting the lights.

Obviously I wouldnt be messing around with electrics meself I will get a certified electrician to do it ... (maybe

) but I just want to know what me options are beforehand and see which is the cheapest and effective way to go .

... and out of the 2 (although hardly think it will happen) I might rather slip coming out the shower in the dark because the lights have tripped than touching a faulty light switch with damp hands and not having a MCB breaker cut out and getting 240v passing through me

I do realise about the regulations and that they dont include fitting RCD on lighting circuit.... but then on the other hand I have Shaverlights in the bathroom on the lighting circuit (i know got cord switch and the shaverlights have got isolating transformers in them but still) then I have the outside lights on the lighting circuit...(I know they are IP rated but I have come across lights where seals or grommets have deteriorated and dampness and water have got into the light fittings) - its for these reasons as well as hands coming into light switches that I am pretty uncomfortable with lights not being protected by RCD regardless of what the reg's say

Risteard81 · 25-02-2017 03:27PM

Andy From Sligo wrote: »

Obviously I wouldnt be messing around with electrics meself I will get a certified electrician to do it ... (maybe )

You don't have any choice. These are Restricted Electrical Works and to be honest it seems you lack the competence to do it safely anyway.

25-02-2017 06:48PM

Personally I would bother, mainly for the following reasons:

1) It is a solution to a problem that doesn't exist.
2) My light switches are plastic and I switch off the power when changing a lamp.
3) I think that it actually results in a net increase in risk of injury.
4) I know plenty of people that got a nasty shock from a circuit protected by a properly functioning RCD yet in every case it did not operate.
5) There is reduced risk of electric from lighting circuits as they only supply fixed equipment.

Andy From Sligo · 25-02-2017 08:12PM

been reading up a bit on it - RCD not only protects human life but also against fire risk - whats not to like , and again an electrician was citing that a damp double insulated (ie no earth) outside light with an RCD would detect the imbalance between live and neutral would trip the RCD rather than catching fire!

25-02-2017 09:19PM

Andy From Sligo wrote: »

been reading up a bit on it - RCD not only protects human life but also against fire risk

Please don't think that an RCD will ensure that devices can't go on fire! Electrical fires can occur when there is no current imbalance.

an electrician was citing that a damp double insulated (ie no earth) outside light with an RCD would detect the imbalance between live and neutral would trip the RCD rather than catching fire!

I think this electrician was confused.
Why is double insulated relevant?

Andy From Sligo · 25-02-2017 09:24PM

2011 wrote: »

Please don't think that an RCD will ensure that devices can't go on fire! Electrical fires can occur when there is no current imbalance.

I always look on safety devices as a 'better to have than not have' - I wouldnt certainly rely on them - I would just like as a piece of mind ... but of course if it does trip rather than electrocute someone or prevent a fire by tripping then thats a great bonus in my books.

I dont get the huge negativity vibe I am getting at the moment - why are people saying its such a waste of time and why that concerns them more than telling me if I wanted to go ahead with it which way the best way to go, whether replace the 2 existing MCB's with 2 RCBO's or fit 1 RCD (RCCB) protecting the 2 existing 10a MCB's

25-02-2017 09:41PM

Andy From Sligo wrote: »

I always look on safety devices as a 'better to have than not have' - I wouldnt certainly rely on them - I would just like as a piece of mind ... but of course if it does trip rather than electrocute someone or prevent a fire by tripping then thats a great bonus in my books.

I think your expectations of what an RCD can achieve are unrealistic.

I dont get the huge negativity vibe I am getting at the moment - why are people saying its such a waste of time

Experience.

The requirements in electrical regulations (written by the ETCI) are based on understanding, experience and risk assessments. They are not just plucked from the air (although it may feel that way at times

).
You seem to have decided that there is a greater risk of electrical shock from lighting circuits than the ETCI do. Furthermore you seem to think that installing an RCD is the best way to mitigate this risk.
I think if the risk was as great as you seem to think it is installing an RCD is not the way to deal with it.

and why that concerns them more than telling me if I wanted to go ahead with it which way the best way to go, whether replace the 2 existing MCB's with 2 RCBO's or fit 1 RCD (RCCB) protecting the 2 existing 10a MCB's

It would be better to go with 2 RCBO's than 1 RCD.

If you really want to reduce shock risk ensure that everything possible is double insulated.

Andy From Sligo · 25-02-2017 10:08PM

2011 wrote: »

I think your expectations of what an RCD can achieve are unrealistic.

Experience.

The requirements in electrical regulations (written by the ETCI) are based on understanding, experience and risk assessments. They are not just plucked from the air (although it may feel that way at times ).
You seem to have decided that there is a greater risk of electrical shock from lighting circuits than the ETCI do. Furthermore you seem to think that installing an RCD is the best way to mitigate this risk.
I think if the risk was as great as you seem to think it is installing an RCD is not the way to deal with it.

It would be better to go with 2 RCBO's than 1 RCD.

If you really want to reduce shock risk ensure that everything possible is double insulated.

Thanks for your advice I will price up 2 x 10a RCBO's then , it put my mind at rest and in my mind (to me) make it feel safer for the future.

And I will price up how much it will cost an electrrician to fit them (would an electrician still fit them even if its against current regs?)

Sorry as well, I didnt aim that 'negativity' bit at you personally as well (even though I done it in reply to your post) I was just picking it up generally on this thread

25-02-2017 10:12PM

Andy From Sligo wrote: »

And I will price up how much it will cost an electrrician to fit them (would an electrician still fit them even if its against current regs?)

It's not against the regulations.
It's just not a requirement.

25-02-2017 11:39PM

All questions answered, I think we should leave it at that.

Protecting lighting circuit with RCD?

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