No earth wire for light

[confused-one]

I'm trying to put new lighting in a house I recently bought but none of the lighting anywhere in the house seems to have an earth wire! (The house was built in 1981 so the electrics should all be of that era).

Re-wiring the whole house is a total non-starter.....so do I have to return my lights and buy ones which do not require an earth wire or can I run an earth wire from somewhere else in to the ceiling rose? (e.g. run it from a nearby switch or socket which does have an earth?)

 

[dingbat]

Before you do anything too drastic, are you absolutely sure there are no earths? It may be that the loop-in wiring is all tucked into the ceiling void with only neutrals and switched-lives actually pushed through at the lights. Try searching in the loft to see if you have a bundle of connector blocks above each light and report back what you find.

If you do find there's more than meets the lighting roses, take a look at the first post in this section, entitled 'For Reference' to make sense of it all.

 

[confused-one]

There are 3 wires - black, red and unsheathed. The unsheathed is silver, not copper, and is appears to be live all around the house. It is sheathed in yellow and used as the common wire for the switches for the landing light but appears to not be used otherwise, just grouped together at each ceiling rose. No sign of an earth wire anywhere!

 

[dingbat]

Sounds like the unsheathed conductor is actually your earth, but they have used the same cable to do the job of three-core for two-way switching. I take it your landing light is on a two-way circuit? In this case the unsheathed conductor is being used as a live between switches which is not uncommon (just bad practice).

If you are sure that this conductor is live elsewhere in the lighting circuit then you'd best call in a spark to check it out.

 

[ban-all-sheds]

In this case the unsheathed conductor is being used as a live between switches which is not uncommon (just bad practice).

That's a helluva understatement...

 

[dingbat]

In this case the unsheathed conductor is being used as a live between switches which is not uncommon (just bad practice).

That's a helluva understatement...

Well, I always reckon the main thing's not to get too excited. Sadly though, I see far too many two-ways done with T & E, using the handy extra bonus wire as a strapper.

 

[securespark]

This is bad practice to the level of g*nad removal.

Imagine tapping into one of these cables along its length for an earth?

I have had several installs like this and meter readings are all over the shop.

DREADFUL!

 

[confused-one]

The thing is, the other wiring in the house has 'normal' copper earth wiring and this is silver so I am far from convinced it is supposed to be an earth. It could well be that the wire has yellow sheathing all the way and that it has just been aggressively stripped back and then poked up ito the ceiling. I will double check this as a matter of interest......but none of this actually answeres my original question. Can I run an earth cable from a switch/socket nearby to the light to safely earth it?

 

[plugwash]

it would make it safe for now

but it is against regs and i would not do it as a permanent soloution

the problem is seperate earths have a high likelyhood of being disconnected while the power is still connected

 

[dingbat]

.....but none of this actually answeres my original question. Can I run an earth cable from a switch/socket nearby to the light to safely earth it?

No. The 'earth' in this case is actually called the circuit protective conductor (CPC) and just as the live and neutrals of a domestic circuit should be run together, so should the CPC. That's what 'twin & cpc' cable is for. The CPC should also be continuous, starting at the consumer unit and terminating at the final luminaire of the circuit. And in any case, if there is no 'earth' connected to a switchplate or backbox it isn't earthed in the first place. Have you tried unscrewing a one-way switchplate and seeing what's behind?

Incidentally, are all three of these conductors housed in a single outer sheath, or are they actually unprotected singles? Or singles run in conduit? Either way, it sounds like you should consider at least a rewire of your lighting circuits.

 

[Big_Spark]

If the core is silver not copper, then it is probably tinned copper, in which case one must question if this is even 300/600V rated cable.

The only possibility is that it is some original FP200, this used to have a tinned copper earth core, but this practice stopped some years back.

Describe the actual cable you have that your talking about.

Is it round?

Is it flexible, but stiffer than Twin and earth?

Are the cores Black and Red?

Does there appear to be some form of foil screen between the cores and the outer sheath?

However, regardless of that, your installation does not sound safe in the slightest, others may not want to scare you, but better to be scared than dead or injured.

Call in a professional sparky. It is the best solution so you can be confident in the integrity of the installation.

 

[confused-one]

Ok, further (quick) investigation leads me to conclude that all of the cabling consists of a dark grey outer, black and red sheathed wires and an unsheathed silver wire.

I don't know how flexible the silver wire is (because it was still live and I needed the lights on....i'll buy a torch after work )

When I say this is live, I am basing this solely upon the fact that my little mains tester screwdriver lights up.....it only lights up dimly but it does light up.

If this silver wire is my earth, then presumably I could disconnect the landing light and return the 3rd wire there to its proper purpose and have a normal earth setup once again?