Telling the difference between earth and neutral wires

bairdyboy1980

Well-known Member
Hi,

I have a problem! I was changing a double socket in my flat. The mains cable behind has one red cable (of course that the live cable) but the other two cables are both black. How can i tell the difference between earth and neutral wires??

I have a digital voltmeter and a socket tester (this tester says on it it doesnt test earth neutral reverses)


:thumbsup:
Robbie
 

Dave R

Standard Member
Can you see where the wires come from, ie; are the seperate cables parts of one cable with a sheath? House wiring is generally "twin & earth", a red and black conductor with an uninsulated earth in the middle. Is it possible that one of the cables has had a black sheath pushed over it, but is in fact uninsulated when it gets to the sheated cable?

Alterntaively, if your volt-meter measures continuity, you could try checking between either of the black wires and a known good earyh elsewhere in the room (ie, the mounting screws of any other socket or switch).
 

skytecbvmo

Active Member
bairdyboy1980 said:
Hi,

I have a problem! I was changing a double socket in my flat. The mains cable behind has one red cable (of course that the live cable) but the other two cables are both black. How can i tell the difference between earth and neutral wires??

I have a digital voltmeter and a socket tester (this tester says on it it doesnt test earth neutral reverses)


:thumbsup:
Robbie
Your not a sparky this i can tell.
If something goes wrong with what your doing and theres a fire ect ect ect.
You do not have a leg to stand on with your insurers.
New laws passed not so long ago now it's like gas YOUR NOT aloud to touch it
so please do yourself a favor and get the yellow pages out .
 

uksparx

Active Member
bairdyboy1980 said:
Hi,

I have a problem! I was changing a double socket in my flat. The mains cable behind has one red cable (of course that the live cable) but the other two cables are both black. How can i tell the difference between earth and neutral wires??

I have a digital voltmeter and a socket tester (this tester says on it it doesnt test earth neutral reverses)


:thumbsup:
Robbie
Some times in old houses u do not get a earth cable they use the conduit as the earth, they should have run a " fly lead " off the back of the metal backbox to the earth connection on the socket.

Use youre mulitmeter to do a continunity check on a known earth to each of the black cables , if u find one beeps then that could be an earth.

Hope this helps.

"The new regulations came in the beginning of last year I think, so just say the work was done before that"
 

Flibblebot

Standard Member
skytecbvmo said:
New laws passed not so long ago now it's like gas YOUR NOT aloud to touch it so please do yourself a favor and get the yellow pages out .
The new Part P regs came into effect in January 2005.
According to the ODPM leaflet, "You do not need to tell your local authority's Building Control Department about repairs, replacements and maintenance work; or extra power points or lighting points or other alterations to existing circuits (except in a kitchen or bathroom, or outdoors)."

If the house is old enough that it doesn't have a specific earth cable, you may want to look at getting your house rewired anyway.
 

Nick_UK

Banned
Go to B&Q and get one of those 13A socket testers. If you have N & E reversed, it will tell you.
 

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