Earth wire in three core lighting cable appears to be live

gacw · 24 Jul 2003

Hi there,

I am currently installing a couple of outdoor lights on to my garage. As I want the additional two lights to work of the same supply and switch as the existing outdoor light, I have spurred the new lighting circuit of this using standard three core lighting cable. The spur goes into an additional fused shut off switch and junction box which will link to two new lights together. When the supply is switch on to the new circuit and even with the new shut off switch being off, the earth cable appears to have current passing through it when I hold my tester to it. Is this possible? Is this static electricity or do you think there is some kind of leak within the cable? When the supply is switch off the earth cable does not light the tester. Please advise.

masona · 24 Jul 2003

I had this a few year ago when one of my 2.5mm remain earth was live using a socket tester and a eletrician told me it was a faulty wire ,so I change the wire and everything now okay.Don't worry,Breezer's the electric guru should be about soon !

breezer · 24 Jul 2003

it would appear i am a bit late (thanks masona, you said soon)

It depends on what type of "tester" I personally do not like any "tester" other than a meter as they have been known to give false readings.

Even so it is worth investigating.

gacw, as you have installed the cable, what happens if you "test" the other end of the earth? (does your tester indicate it too is live?) and also are any of the other cores (wires) near it when you "test"

also what happens if you "test" an original earth (before you installed your cable)

Also make sure that all the connections are tight

which type of "tester" are you using? is it one of them "proximity testers" with the white end and the tip lights up red, or is it a "neon screwdriver type"

If it is one of the proximity testers they light up if you rub them on your jumper

j.m · 18 Jan 2004

Hold prox type of tester in left hand, use neon type tester wiv right hand

Whoosh they both light up....... Umm Pretty

breezer · 18 Jan 2004

your point?

Scoby_Beasley · 19 Jan 2004

breezer said:
your point?

He's a bright spark

. Didn't work for me

Marting · 11 Mar 2004

Hi Guys. Sorry for just jumping in like this but I am having a nightmare with something similar. I happen to tighten up a light switch the other day and I noticed that the light in the phase tester I was using lit up. I removed the switch and tested the earth and sure enough it lit up. I tried a socket and light switch in a different area and the same problem. So is it just a crap tester or can I test it with a meter or should I call an electrician in?
Thanks

Big_Spark · 11 Mar 2004

Gents, the comment Breezer made is valid and true.

These voltage "testers" are not testers at all, but indicators, and pretty poor at that.

Many of them, though not all, will detect any voltage from around 10Vac/dc to about 600Vac/dc with no diferentiation between them.

A good quality one will not detect anything below 100V normally, but I'll bet you guys don't have one of them ones?

Depending on your installation, as in the electronic equipment you have there, you may well have from 0 to 30V ac/dc on the earth line, this is caused by the electronics and other inductive loads, like fluorescent lights.

It is something that is worth investigating, but to check for voltages PLEASE use a decent METER and never rely on a volt stick.

securespark · 11 Mar 2004

pointless post i know, but try standing on live cable or flex and hold a volt stick - it lights up.

Big_Spark · 11 Mar 2004

securespark said:
pointless post i know, but try standing on live cable or flex and hold a volt stick - it lights up.

Good party trick though

Nice one.

ban-all-sheds · 11 Mar 2004

Better party tricks:

securespark · 11 Mar 2004

WOW!!

Do they light up when you tread on a live flex????

ban-all-sheds · 11 Mar 2004

Not sure, but I think you might light up if you were in the same room....

Geof_t · 11 Mar 2004

Hi gacw

Firstly don't take any chances with your electrics, if you are not sure ask someone who will know, like a lecky.

If you are messing with the electrics, it is well worth investing in a meter, a cheapo £15 piece of kit will do for the occasional meddler.

I would expect your trip to go if your earth was live, but anyway a common problem i keep coming across when someone has modified their electrics like spurring off, they do not cover the bare earth wire with a sleeve, and when the plug is refitted the earth contacts the live strap across the back of the socket.

hope this helps

securespark · 11 Mar 2004

Live strap across the back of the socket??

Care to elaborate?

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Earth wire in three core lighting cable appears to be live

breezer

breezer

Big_Spark

Big_Spark

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