Class I light fittings, no Earth, what would you do?

[Paul.M]

Did an EICR last week, a few small things to clean up but the main thing is that 3 of the upstairs light fittings are class I metallic with no cpc/earth. Doing the remedials tomorrow and talking to another spark he says that the earth to the fittings has to be a min of 4mm csa!

Now, I've learned from a few good sparks and I've work for/and employed a few good sparks and never have I seen a 4mm earth in a domestic light fitting. Have I/we been doing it wrong for all these years? My friend makes a very good point in the regs, 543, and now I'm on the ropes trying to defend my decision to throw in a 1mm, any help on this would be appreciated because there's a couple of pints riding on this lol.

Do you or have you ever put a 4mm csa to light fittings being fed from 1.5mm twin? I never have but I may have to change my ways if this is correct.


Ps, foot note on install info:- 1970 rewire, red+black, 1.5mm cable no cpc on any of the upstairs light circuit, IR @ 11M and the customer is my neighbour and a good friend that always gets me a pint after working for him (builder), think I've covered enough info unlike others that ask for help lol.

 

[SirKit Breaker]

Paul, save the argument, fit class 2 fittings, job done. But this is a first on me, and i cant be bothered looking at the regs. You could do the adiabatic and work it, but i dont know of a situation where the CPC has to be larger than the Line or Neutral conductor, but i may be wrong! And would be interested to find out.

Cheers.........Howard

 

[spark 68]

Paul,

The reason your spark says it has to be 4mm is, because less than this requires mechanical protection throughout it's length which would be difficult to fit. It is nothing to do with the adiabatic or any other electrical reason.
I will try and find the regs later.

 

[Paul.M]

Good point spark 68 the 543 regs do state mechanical protection or not part of the cable itself, but even so 4mm!

It should say that the new earth should be pvc/pvc or in confinement?

I don't normally get caught out on domestic regs but I think I'm paying for the beer Friday night if I can't come up with an answer! I wonder why scams/labc and other sparks have never pulled me up on it??? eemmm.

 

[spark 68]

Yep reg. 543.1.1, if it is not integral to the cable min 2.5mm with mechanical protection, or min 4mm without.

It is also supposed to follow the same route, it would be the same amount of work to just renew with a run of T+E, or as Howard said replace the fittings with class II.

 

[Paul.M]

Ok, has anybody on here ever put in a 4mm earth or do you just use a 1mm?

Some very good sparks on here and no one has ever mentioned this before on any thread (to my knowledge). It would be good to have a show of hands on the 1mm / 4mm divide lol.

 

[tigerpaul]

As spark68 says!

 

[Guitarist]

4mm if separate to cable, and not mech protected. I think the reason it doesn't get discussed much is that we either go down the rewire route or the class 2 fittings route. If you are going to the trouble of getting a cpc to each point, then you may as well run in a new T&E.

In short.... what the others said

 

[Paul.M]

Ha, that's the problem Guitarist he wants to keep the expensive fittings and does not want to have a rewire of his very nice decorated house (typical builder, called the sparky after he started to plaster and paint).

Ok its up to him after being given a recommendation on a cert but if he doesn't want to change the fittings or install an earth to them, my back side is covered. Anyway, what is the worst that could happen?

I'm still asking the question of:- Your installing an earth, what size would you use? I'm happy with 1mm after knowing the full house is good after an EICR and a MWC, I'll stand in court knowing that the circuit is safe.

 

[Guitarist]

I'm afraid that after 20 odd years in industry, where I got my backside kicked for the slightest transgression, I am really fussy now in domestic.
Give him a written notice that class 2 fittings must be fitted to ensure safety unless new cables/4mm cpc are to be installed, to cover yourself. Tbh, if a customer ignores something I strongly recommend then that's the last time I deal with them.

 

[Jimmy Boy]

Excellent posts
J

 

[Richard Burns]

Hmm I would say that if you are using a single core single insulated unsheathed conductor as a cpc then you would need to use 4mm cable to avoid the risk of damage to the cpc. If you used insulated and sheathed cable then you could use 2.5mm. Without some interpretation of the regs I can't get to 1mm as a single cable for a cpc.

However the regulations state this if it is not an "integral part of a cable" however since a single core cable is a cable, then any conductor that is also a cable is an integral part of a cable! Adiabatic only applies!
The other alternative is to consider containment, one could (maybe) consider that the space between floorboards is containment as it could well be smaller than some large ducts that are considered containment, it surrounds the cable on all sides and can only be opened with a tool, where is the problem, ahh probably not made to BS standards, damn.

Electrically I would have no problem with 1mm as a cpc inside or outside of a cable when earthing a 1.5mm live conductor and really if there was no chance of damage to the cable because it was enclosed by something all the way along it should be fine, but regulations wise I think you are reaching for the wallet on Friday!

 

[Jimmy Boy]

I might have missed something but hell of a job getting a 4mm cpc in to a light fitting ? if it's in the ceiling void and not likely to get damaged what's the issue with a standard 1/1.5mm ? how is more likely than all the other cables to be damaged ?
J

 

[spark 68]

I might have missed something but hell of a job getting a 4mm cpc in to a light fitting ? if it's in the ceiling void and not likely to get damaged what's the issue with a standard 1/1.5mm ? how is more likely than all the other cables to be damaged ?
J

It is just as the regs stand Jimmy, see 521.10.1 and 543.1.1, and the other part of the regs relating to a seperate CPC states it has to follow the same route or immediate proximity as the live conductors 543.6.1, so this requires chasing out etc. where the existing twin cable is, so you may aswell just run some new T+E in anyway.

 

[Marvo]

If the fittings are ClassI they're double insulated, do they really need a cpc connection if they're not in a zone?