Hi all,

This is a home electrical question - in case there are any sparks on the forum!

Hoping for some advice, I ran a cable to some light fittings some time ago during refurb of my place. I've now gone (2 yrs later) to connect that light fitting... and nothing. Dead.

I wired my place all myself, then had a spark come and sign it off. All connected circuits passed with flying colours. FYI, as that circuit was not connected it was not tested.

I've rewired, reframed, plastered and fitted cornice. All of which might have brought the chance of a screw or some other damage hitting the cable after it was run.

The live feeds through the house run to all the light switches, in this case a 4-gang dimmer. Two of the gangs are connected and running. So the live feed is fine.

Then from the switch this particular run of 1.5 T&E heads up a wall, across a section of ceiling then behind the cornice to a wall light. In all around a 4m run.

I popped a 9v battery on the pos only, then, with a long, separate cable back to the battery via my multimeter to check continuity. I then checked the earth and the neg separately the same way. The earth and the neg test ok. The live is dead.

This cable must have a break somewhere, or taken a screw hit.

When I connected the switch and the light, the breaker/RCD doesn't trip. So if it is a screw it's broken the live and not disturbed the Earth or Neg. Which is a bit weird. But possible I guess. Unlucky too.

So hoping to get some tips if anyone can offer some wisdom. Especially to avoid making a load of holes in my lovely cornice. I've done quite a bit of googling, have seen cable tracers but proper ones are £400+.

Thanks in advance.

Greg Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

I don’t think even a cable locator would work, because it would detect the non broken wires. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

If you have broken the live cable you might as well give up now and look to alternatives, you will never find the break without starting at one end and digging the cable out of the wall until you find the damage and even then you will need to replace the cable.
One alternative you may wish to consider,

Does the light fitting you want to fit require an earth connection?

If so you need a new cable, if not you could use the two conductors you have available ie neutral and Earth as live and neutral for your light fitting.
Personally I would use the existing blue neutral as live and the earth as neutral.
This would mean sleeving the existing neutral cable ends in red tape and the existing bare earth cable ends in blue tape
for future identification. The earth will be 1mm2 but perfectly adequate for the intended use.
I would quite happily do the above in my own home but the choice is yours.

Thanks Mike. I do think energising the cable would allow for it to be detected. But I think I'd need some proper kit. Fault Tracers, proper ones are £400+. I could hire one but I've not used one before.

Wow nicedayforit - that's actually a really great idea.

Load is tiny - 2 x 75w bulbs, that's it. And no the fittings don't require earth.

Would this be badly out of code though do you think?


Greg Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway

replace the 75w bulbs with leds ones and it'll be even less of a problem Greg..  ... - .- -.




Y. O. L. O.
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gonna_go_double_r wrote:

Would this be badly out of code though do you think?

No it’s not in accord with the IEE Regulations, strictly speaking an earth connection has to be made available to each fitting whether it is required or not. Using a blue coloured cable as a live cable is not that uncommon provided each end of the cable is clearly identified with coloured tape or even better shrink sleeving.
Using the earth cable as the neutral is not the end of the world, neutral and earth are at the same potential anyway, it may even be the case that earth and neutral are connected together at your property anyway, mine are.
As I say my suggestion above is what I would do myself given your situation, knowing that the suggestion is safe and will not cause any problems. The purists will throw their arms up in horror at the suggestion no doubt but such is life.
I'm not quite sure how you managed to damage your cable, I presume you covered the cable in the wall with a metal capping?
I note you have had the installation signed off.
I have to comment on your choice of two 75W lamps to your fitting. I had similar but chose to change to all fittings throughout the house to led equivalents with the result my electricity consumption went down significantly. Using led lamps also gets rid of the potential heat damage to fittings which occurs gradually.

If you think the cable is damaged I would replace it. Running current through a partially damaged cable would be too risky for me, but then I live in a wooden house!

Would one of those voltage sticks work, ie the cables not to deep in the plaster.
They are like a pen with an end that lights up when the live is passed over?
£10 to £15.00 approximately.
Obviously would need to be connected to mains supply.

I do not think mixing the cables to different sources of using the earth as a feed is wise. You have to consider the next user.

Did you cap it with plastic or metal ??
Just thinking a neon screwdriver might pick up the live wire to the break if it is not very deep? and only covered in plastic.

Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

Alistair wrote:

gonna_go_double_r wrote:

Would this be badly out of code though do you think?

No one would sign it off - so the only way around it would be to install a lamp socket - which could be signed off, then put a lighting plug on the end of your cable. Depends whether you have somewhere that could be done out of sight......

KurtVerbose wrote:

If you think the cable is damaged I would replace it. Running current through a partially damaged cable would be too risky for me, but then I live in a wooden house!

nicedayforit wrote:

....... you could use the two conductors you have available ie neutral and Earth as live and neutral for your light fitting.

Or, if you don’t want to risk killing someone by electrocution or a fire, you could simply replace the cable!

Given these potential consequences, isn’t a little disruption in pulling out the damaged cable (attaching it to a drawstring as you do so - to pull through a replacement cable) so bad? Better still, get an electrician to do the job for you, in order to comply with Part P.

Sorry to go off on one, but I see the consequences of poor practice.

Hi thanks for the comments.

I realise the right thing to do is to re-run the cable. If it were only that simple; it's plastered in (behind channel trunking) but there are too many bends and dodges to 'pull and replace' and it will be a big deal to re-run it.

I'm interested to re-run a section - if only I can locate the break. Then I would probably use a allowable joint (e.g. maintenance free junction box) and halve or third the amount of replastering, painting and general mess by only re-running what I need to.

I like nicedayforit's suggestion and I'd be interested to hear if an earth and neg could be repurposed to a pos and neg (via earth) from a regs POV. Specifically, the earth, although bare is actually sheathed by the outer insulation. Wiring is allowable by individual insulated cables, more common in commercial installations.

The second reg. I may be missing (as pointed out a bit higher up) is that an earth would no longer be available at the fitting. If that is mandatory (must look that up) then I might be able to provide an earth from another location more easily.

If I did satisfy myself that this could all work, be safe and meet Part P then I'd heat shrink the correct colours for a decent length at each end.

Then I'd get it tested.

Otherwise I'll do a partial re-run. Otherwise a full re-run.

Thanks for all the comments and inputs so far.

Greg Cheers, Greg
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2011 Vogue SE 4.4 with lots of toys in Stornaway