ageing rellies want a new hall ceiling light
took a look - no earth just L & N pvc sheathed multi strand cables look original 50s? 60s to me...
current light fitting is large exposed metal base and glass globe....
What technically should I do here?
and pragmatically what would I be best doing?
Jim K
Depends on if it really is a class I (i.e. "must be earthed") fitting or not... if it is, then one should either provide an earth for it, or replace it with a class II fitting.
Now how difficult that is ,depends on if you mean the whole circuit lacks and earth[1] or just the flex connecting the pendant to the rose lacks an earth. If its just the flex, then that can be replaced with 3 core.
Either the "right thing", or ignore it.
Right thing would range from rewiring the whole circuit, or disconnecting from the circuit and taking an earthed feed elsewhere for that light.
If the above is a non starter, and they really don't want to lose the metal fitting, then see if you can at least get RCD protection for the circuit (RCBO perhaps).
[1]
I it is a new fitting in the existing location then I don't believe there is any obligation to bring it up to standard. An extra fitting is a grey area where most professionals will put the fear of God into the customer and do a proper job - in extremis update the whole lighting circuit.
Pragmatic solution? I think you know that one already!
I never did understand this earthing of lights though, after all everything else these days is two core and double insulated. Brian
Its precisely because not everything is two core and double insulated that it is a problem. There are plenty of Class I fittings about, as well as quite a number of trendy metal faced light switches.
Would it be possible to lift a floorboard and run an earth cable to somewhere?
Bill
If this is 50s wiring I would imagine it's wired live to the switch, then feed/return to the light fitting.
If cable in ok condition, just fit nonmetal light fitting or a class II metal one. No safety problem then.
NT
The likeliest place to get a fatal electric shock in the home is from a light fitting. This is/was because the cables deteriorated with the heat and the waggling about and people got a shock and fell off the step ladder.
The fall killing them, not the electric.
So, if a class 1 fitting was installed in a lighting circuit without an earth, what are the real world safety risks?
It will presumably only be touched when changing a lamp?
indeed & with hopefully the switch "off"....
Cheers Jim K
I have been warned not to clean my fluorescent light when it's switched on. The electrician said there was no earth and he wasn't supposed to be fitting it.
In reality, not many - but some...
This is a general problem compounded by the age of some lighting circuits. Often they were the first to go into a house, and are probably one of the more likely places to still find old flaky rubber insulation.
IME its not uncommon for the wires that run through the metalwork of multi arm style luminaries to suffer insulation failure or damage over the years anyway (often as a result of a batten holder working lose, and rotating somewhat as the lamp is changed). So there is some risk of the metalwork becoming live as a result. Other light fittings that are wired and then fixed in place like wall lights, also have a reasonable chance of pinching a wire and suffering the same problem.
If the circuit/fitting was earthed, then this would be a non issue since the protective device would trip/blow.
With it unearthed, then it means that the person changing the lamp (or operating the metal switch) will be exposed to a mains voltage. The risk from this will obviously vary with he circumstances. So warm dry day, on carpet on floorboards wearing shoes etc, you won't even feel a tingle. Concrete floor in your bare feet, or with your leg touching a radiator, then possibly a half day out with an undertaker.
Yup usually, but note the issue applies to metal faced switches as well. Note as well that houses are getting shorter and people taller, so the ease of doing that increases. Hopefully one would only change a lamp with the fitting off, but as you know, that is not always obvious. Even with it off, one hopes the functional switching is in the live and not the neutral.
How is that different from 10s lighting?
Alex
If one met this issue, say in the final 50mm of the L & N when removing the old fitting, what's the prognosis? - rewire required or tape up or shrink sleeve or ??
(& many thanks for the detailed walk through John)
Cheers Jim K
shock & electrocution, but the number of deaths from lighting is near zero. There's a very long list of other risks far greater in life that we all ac cept daily.
Its upto you. Often its only the exposed rubber end that's perished, when t he rubber cable has secondary inuslation. Then sleeving will suffice. Howev er it would suggest that all such junctions are liable to be that bad - but if it is only the ends perished its a lunch money diy job.
If the whole run of rubber's perished, often the way when single insulated twisted wire was used, I'd remove the fuse promptly.
NT
insulated twisted wire was used, I'd remove the fuse promptly.
And fit what? I find a nail usually works.
Bill
Well both probably... rubber in that state is possibly a serious fire risk - however it does tend to fail at the ends first. Either way you should take it as a strong indication that the circuit needs rewiring ASAP.
I would say that if the circuit passes an insulation resistance check, then you could get away with sleeving and reconnecting - but only as a short term fix. If the insulation fails, then disconnect it immediately.
The last time TRS (rubber) was in use was almost sixty years ago. Long overdue for replacement. There will be incipient faults everywhere. Too important to bodge. Wiring standards and the intrinsic safety of the fitments used were all much lower back then too.
Have you had a look at the rest of the wiring? It could, at worst, mean that the whole house wiring is unsafe. No unknown in my experience.
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