Wiring help for outdoor lamp.

[ss]

In the image below are the connections that are fed from an indoor light switch. On the mounting plate there are 3 wires Red/live, black/neutral and another thinner wire that is black and unconnected. Would this be an earth?

On the connections to the lamp there are 3 wires brown/live, blue neutral and an earth, the earth connects to the metal fram of the lamp and in to the connector block but then does not feed in to the system. Is this correct as in my mind the earth is useless if it doesnt earth anywhere.

Secondly I am trying to feed an led flood in to this which will require an earth, where would this earth wire go assuming that the wall plate wiring doesnt have an earth unless the thin unconnected black wire is the earth.

Image:

[Bob Minchin]

That third wire does not look black to me but instead seems to be bare oxidised copper and so is quite possibly an earth. Look at the wiring of the inside switch and you should be able to check if it is connected to earth or left floating. Yes you do need an earth so if the thinner wire is not connected to earth, then make a connection to earth at the indoor end.

[ss]

Thanks Bob you are indeed correct, on closer inspection it is oxodised copper, so I will check the earth connection indoors at the switch. Looks like that earth was never connected or came loose at some point.

[Mike Clarke]

But bear in mind that, depending on the date your house was wired, there is no guarantee that an earth conductor in any lighting circuit is actually connected to earth. You will need to check continuity between the apparent earth conductor and a known earth point.

[DerbyBorn]

Mike Clarke wrote in news: [e-mail]:

Put some green/yellow sleeving over it. costs pence or cadge some.

[ss]

Sorted. I just stripped a piece off another piece of cable I had.

[Brian Gaff]

Its almost certainly quite an old installation, and many did use bare wire earths, the ones in my house are like this. I find it hard to believe that this wire or a connection from it is not present on the light its wired to. Maybe its been clipped off and is still available further down. I think it is indeed prudent to attempt to connect this to the lights that are switched, as otherwise there could be anasty surprise if a short to live occurs from case parts due to weather damage or somesuch.

Brian

[Mike Clarke]

Such an installation would likely pre-date the requirement for earthed lighting circuits. It's possible that a convenient length of T&E was used to extend the circuit to the outside light, in which case the other end of the "earth" wire probably isn't connected to anything.

It's also possible that T&E was used for the original installation (because that's what was conveniently to hand) but the CPC was never connected to anything. Our previous early 1960's house was wired like this, the CPC was just cut back flush with the end of the cable outer sheath at most fittings :-(

If T&E has been used when making additions to a non earthed lighting installation then connecting the CPC to the casing of light fittings etc. could create a safety hazard. In the event of an earth fault in one fitting all the other fittings connected to the same floating length of CPC would become live.

Hence the reason for suggesting the OP should check the continuity between the exposed "earth" conductor and a known earth point in my earlier post.

[ss]

The house was built approx 1980 the extension which is where the wiring is was built 1989.

[meow2222]

unsleeved earth wires are modern.

NT