Electrician refused to put in extra RCD/RCBO protection

Solair

We were having an elderly relatives house partially rewired recently and I asked the electrician to install RCD protection, preferably RCBOs on the lighting circuits. She is a little less light-fingered than she once was has had accidents where she has touched live light fittings while changing bulbs and I thought it might make the situation safer. She also has a lot of older light fittings in the house which we don't necessarily need to replace immediately.

She's also a lady who is very unlikely to give up DIY. She's in her late 80s but still keeps a full set of tools for odd jobs.

There are 4 light circuits and a very spacious 2 row new board. I cannot understand why he couldn't have replaced the 10A breakers with 10A RCBOs with a 30mA trip.

He gave me an explanation along the lines of the filaments in the light bulbs would cause nuisance tripping.

To me that sounded like utter b/s as it would mean that if a light bulb blew in a lamp, it would trip the RCD which doesn't happen.

Is there any reason why he could not have installed these? I was quite willing to pay extra for the fittings and I can see no physical space problem on the board.

Did he have a point?
Or, was he clueless?

northdublin

ive not seen rcd/rcbo fitted on lighting circuts before. i would think with normal incndesent lighting there could be a posibillity of them causing the switch gear to trip. i have seen where lighting was taken from a socket circut protected by and rcd that it did cause a lot of tripping so the sparks might have a point.

bertie1

If you say that only part of the wiring was replaced then there is every chance that the neutrals for the lights are looped. With looped neutrals wired in singles there is every chance the electrican could not isolate the neutrals for the various circuits thence the rcbos could trip as a phase could be coming through one rcbo and the neutral to a light through another.

Andrea B.

ive not seen rcd/rcbo fitted on lighting circuts before.

Are they not regulation on 5A socket lighting circuits?

enmac

Bertie is spot on here - probably not practicable to isolate the neutrals for each circuit - the other option is to group all the lighting circuits together through one RCD but this could prove dangerous as you would be left in total darkness if one circuit developed a fault

davelerave

Ya therd be no problem if he could sort the circuits and fit the rcbos a single rcd would be a danger

DublinDilbert

TBH if someone is going to stick their finger into a light socket the RCD might or might not save them...

They'll still get a jolt, if they are standing on a chair they could simply fall and kill themselves, never mind the RCD!

ART6

From recollection I think flourescent lights trip RCDs and RCBOs.

davelerave

ART6 wrote: »

From recollection I think flourescent lights trip RCDs and RCBOs.

I wasnt aware of this theres plenty connected to rcds in shops although they dont seem to have capacitors afaik. ive seen capacitors in lighting ccts trip rcds on other ccts to which theyre not connected

fishdog

Lights will not trip an RCD.

I have pluged many different types of lights into sockets and never tripped an RCD in doing so! In fact some types of lighting circuits must have RCD protection to comply with the regulations.

In TT installations the entire house is protected by an RCD (100mA) and lights in those houses work just fine.

As someone pointed out earlier, it can be hard to fit one at times because neutrals may be mixed up.

davelerave

fishdog wrote: »

Lights will not trip an RCD.

I have pluged many different types of lights into sockets and never tripped an RCD in doing so! In fact some types of lighting circuits must have RCD protection to comply with the regulations.

In TT installations the entire house is protected by an RCD (100mA) and lights in those houses work just fine.

As someone pointed out earlier, it can be hard to fit one at times because neutrals may be mixed up.

Not in general anyway that i know of(although the comparison with the tt system is irrelevant as the loop impedances are much higher and the rcds 100ma ) and less so now with the advance of lighting techology and better fault discrimination of rcds but there were issues with electronic starters and also harmonics in fluorescents (i have encountered this problem myself)

fishdog

Not in general anyway that i know of

Sorry, I dont understand. What is not in general?

the comparison with the tt system is irrelevant as the loop impedances are much higher and the rcds 100ma

I was not comparing. I was just stating that with certain installations all of the lights within an installation are connected through a single RCD. In some countries in Europe this is the norm for all domestic installations.

I acknowledge that this type of installation is not the norm, but it exists and a 100mA RCD will not suffer as much from nuisance tripping.

and less so now with the advance of lighting techology and better fault discrimination of rcds but there were issues with electronic starters and also harmonics in fluorescents

I dont know what you mean here. Discrimination wont come in to it if nothing trips. I dont think any house would be large enough to have enough fluorescents in it to cause problems with harmonics.

I have seen issues arise when large numbers of fluorescents are operated by a single switch (perhaps this is what you mean), but in this case we are talking about a house!


To put it simply, I have seen large numbers of fluorescents with electronic starters used as temporary lights and powered them by plugging them into a socket. In fact this was standard practice on many large construction sites that I worked on.

Also there seem to be no problems with 5A lighting circuits on RCDs.

dolittle

as far as i know its going to be introduced that lights will have to be on an rcd/rcbo, its not confirmed yet if they will be on a seperate rcd/rcbo or one for the combined sockets/lights

fishdog

Yeah, I heard this may happen for bathrooms. I dont know if it is true.

davelerave

rcbos are going to be required for bathroom lights definitely and i notice alot of ground lights are marked on the box that they require an rcd.ive wired large houses using rcbos protecting all the lights where there were lighting sockets everywhere not aware of any issues recently

fishdog

rcbos are going to be required for bathroom lights definitely

Interesting. I have been off my tools for a bit so I have not wired a house in a few years. If I were to wire one again I would use an RCBO for each socket circuit, its just a better job.

Recently someone on this site said they were about €20 each, that will only put the overall material cost up a little.

dolittle

one rcbo per circuit is the best way to do it

Dotsie~tmp

Fluorescent lights, some CFL's and other types of discharge lighting with trip the **** out of RCDs RCBOs. Just not worth it for the spark.

Dotsie~tmp

fishdog wrote: »

Interesting. I have been off my tools for a bit so I have not wired a house in a few years. If I were to wire one again I would use an RCBO for each socket circuit, its just a better job.

Recently someone on this site said they were about €20 each, that will only put the overall material cost up a little.

I agree. The problem is however in a house with maybe 6 circuits needing protection that's 6x €22 plus most likely needing a 3-row board for space which doesn't come pre-assembled so you have to spend a fair bit of time wiring up the board carcass yourself. That's an extra €110 for RCBO (minus RCD) and I'd say €40 for the board cos buying MCB on their own is more expenive. Not even counting the money you need for the time it takes to make up a domestic type setup.

Lets say an extra €200 to make it worthwile. Its surprising how hard it can be to get that little out of people. Who then turn around and get 5 grands worth of warrdrobes in while ur on the job.

fishdog

Dotsie~tmp, I agree with you but:

I agree. The problem is however in a house with maybe 6 circuits needing protection that's 6x €22

Yes, but you can take off about €5 per circuit for each MCB you dont have to buy!

plus most likely needing a 3-row board

Yes, another €50 shoud sort that. Also some 2 pole busbar. Perhaps even a 4 row, it means lots of space for future stuff like din rail timers etc. You can never have too much space.

so you have to spend a fair bit of time wiring up the board carcass yourself

Quick enough when you have lots of space in a big board and 2 pole bus bar. Easy to keep the neutrals in order.

cos buying MCB on their own is more expenive

Then dont, buy boxes of 12. It is quite cheap.

Lets say an extra €200 to make it worthwile

Ok, but €200 is not alot extra to someone that is building a house. If you have a fault you will also save alot of time finding it.

Its surprising how hard it can be to get that little out of people

At times I have to agree!!

I used to buy 2 x hager 2 row boards and join them to each other, side by side. Both doors closed together in the middle. Lots of sapce, cheap enough and lots of cool looking stickers to make the board look really good.

Nuravictus

Why not wire the circuit so they light only has a live at it when its on ? It would be more expensive since you would have to do it in Singles but thats what Dublin Corporation are doing now in all the new houses in Ballymun.

Stoner

so back to the OP.

Can we advise that "Yes" a separate RCD for all lighting circuits would would depending on the wiring in the consumer unit ??? (if its a normal house this should not be an issue the lighting cables should be easy to spot)

So to answer the question, can we agree on a Yes?

Taking into account

If the wiring is in bits (possible with the age of the house)
If you have discharge lighting (unlikely)
Earthing system not able to work with it, (it should be fine)
If you have over 200 fluorescent lights all switched by a contactor on a single switch (unlikely)
The RCD wont be much use anyway if your on a chair and old (likely)
etc

There is an excellent chance that it should not be an issue to fit an RCD to feed all the lighting MCBs if that gives the OP some peace of mind.

Like many things on this forum, it's difficult to offer definitive help as we cant see the installation, but IMO Yes he should be able to fit the RCD for you, it might be useless, cause you some unwanted tripping etc. but I don't think it will cause any problems.

Dotsie~tmp

I think there is also a safety or liability element to consider here. I think we can all agree RCD/RCBO circuits are more likely to develop some fault condition by their nature. Especially in an extreme condition (fire, flood maybe). Losing lighting at night in any situation for an elderly person could pose obvious risks. This reason and not being backed up in regs currently is why i would not touch this job.

BTW have you considered some plugin lamps as a solution. Not ideal i now. Or why not change every lamp in the house to a CFL or flourescent. The long life time mean she shouldnt have to be at them.

fishdog

You could also use 12 volt downlighters. It could be wired so that the light switch only has 12 volts at it, so that even if you somehow got made contact with a live conductor it would only be at 12 volts, not even enough to feel.

I think we can all agree RCD/RCBO circuits are more likely to develop some fault condition by their nature

True

Losing lighting at night in any situation for an elderly person could pose obvious risks.

Good point

Bruthal

davelerave wrote: »

I wasnt aware of this theres plenty connected to rcds in shops although they dont seem to have capacitors afaik. ive seen capacitors in lighting ccts trip rcds on other ccts to which theyre not connected

The old wire wound choke fittings had a capacitor to counteract the inductance to keep the fitting PF close to zero. The older wire wound choke`s sometimes tripped RCD`s.

New ones are electronic

Bruthal

DublinDilbert wrote: »

TBH if someone is going to stick their finger into a light socket the RCD might or might not save them...

They'll still get a jolt, if they are standing on a chair they could simply fall and kill themselves, never mind the RCD!

Well if its a shock from live pin to earthed metal light fitting it may trip the RCD, if its live to neutral pins with no earth contact it wont trip anything. Standing on the chair will more or less completely eliminate any current flow through a person to earth that way.

Even standing on floor in dry shoes will eliminate current flow to earth from 230v to almost zero, although im sure lots wont believe that.

davelerave

The electronic ballast are earthed and have a leakage of ~0.5 mA afaik.
You can touch live cables alright if the fault path is high-resistance.I've seen it done upstairs in domestic.

Bruthal

davelerave wrote: »

the electronic ballast are earthed and have a leakage of ~0.5 mA afaik.

Could be, im not sure of the leakage, Although most items would probably have some leakage even if neglegible. If the electronic ballast was not earthed but double insulated then there would be no real earth leakage from that.

Bruthal

davelerave wrote: »

The electronic ballast are earthed and have a leakage of ~0.5 mA afaik.
You can touch live cables alright if the fault path is high-resistance.I've seen it done upstairs in domestic.

Yes true. Although standing out on the path outside once ground is dry and dry shoes on will give the same result. I remember 20 years ago kneeling while connecting a concentric cable to an ESB mini pillar and could feel a tingling in knee. Someone had used screw driver as a chisel with hammer and the steel was exposed at end of driver so live onto hand. And still did`t recieve a shock, just tingle through jeans from knee to ground.
Would`t recommend trying it though

davelerave

try it on an rcd protected circuit first:D

Bruthal

davelerave wrote: »

try it on an rcd protected circuit first:D

Yes it would trip quick enough if you get a decent jolt. I tripped one before (not intentional) but did get a good shock across fingers. It was in a commercial dishwasher i was workin on and out went the RCD

Just off topic sort of,,, on 10 kv ESB lines the lines between the 38 and 10 kv transformer are delta delta and so there is no earth path for fault current. But ye still get a fatal shock on contact with a phase. Usually fatal anywy. The lines are monitored like a sort of 10kv 3phase RCD so if one phase contacts earth it does not trip out, but sets off an earth fault alarm in the 38kv substation