Hi,

I'm trying to put up some new wall lights and it would appear that the
three wires are not correctly identified - can anyone tell me a simple
way to find which of the two low potential wires is earth - only tool
I've got access to is a multimeter.

Is it simply the case that I need to connect a cable to the outside
earth (pole in the ground) to one terminal of the multimeter and the
other to each of the offending wires coming out of the wall (the zero
volts ones) and choose the lowest resisance one.

Out of interest what would the consequences be if I connected these
incorrectly (no RCD or earth leakage trips in the fusebox)

Thanks
John


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Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

I'm trying to put up some new wall lights and it would appear that
the three wires are not correctly identified - can anyone tell me
a simple way to find which of the two low potential wires is earth

Throw the double pole isolator on your consumer unit and unplug every
appliance in the house, particularly those with metal cases, such as white
goods and computers. Turn off any immersion heaters at the isolators. Then
resistance check the cables to be tested to nearby radiator pipework. The
neutral should show a high resistance, whilst the earth should show a low
one. If you don't isolate the neutral by throwing the isolators and removing
the plugs, you will also get a low resistance in the neutral, so won't be
able to tell the difference. If you have plastic pipes, or both tests are
high resistance, test to the earth terminal of a 3 pin socket.

Out of interest what would the consequences be if I connected these
incorrectly (no RCD or earth leakage trips in the fusebox)

It would work, but it would be dangerous.

Christian.

In article lgate.org,
"John Asdf" writes:
Hi,

I'm trying to put up some new wall lights and it would appear that the
three wires are not correctly identified

You might be right, but you have given no clue why you suspect this
to be the case.

- can anyone tell me a simple
way to find which of the two low potential wires is earth - only tool
I've got access to is a multimeter.

Trace back to the other end of the cable and ensure it it connected
up properly. A multimeter isn't going to help much. It sounds like
the wiring might need reinstalling correctly.

Is it simply the case that I need to connect a cable to the outside
earth (pole in the ground) to one terminal of the multimeter and the
other to each of the offending wires coming out of the wall (the zero
volts ones) and choose the lowest resisance one.

No. You need to verify that the wiring in the circuit you are working
on is correctly connected all the way back to the supply.

Out of interest what would the consequences be if I connected these
incorrectly (no RCD or earth leakage trips in the fusebox)

Someone might get killed.

--
Andrew Gabriel

"John Asdf" wrote in message
news:86d34315853044846a8e525fbb387c33.22215@mygate .mailgate.org...
Hi,

I'm trying to put up some new wall lights and it would appear that the
three wires are not correctly identified - can anyone tell me a simple
way to find which of the two low potential wires is earth - only tool
I've got access to is a multimeter.

Is it simply the case that I need to connect a cable to the outside
earth (pole in the ground) to one terminal of the multimeter and the
other to each of the offending wires coming out of the wall (the zero
volts ones) and choose the lowest resisance one.

Out of interest what would the consequences be if I connected these
incorrectly (no RCD or earth leakage trips in the fusebox)

Thanks
John




Find out at the switch end. Are the cables to switch colour coded correctly
? Does the switch have both live and neutral from the main lighting circuit
passing through it ?

If you do find both live and neutral at the switch, then it is just a case
of putting your multimeter on Ohms check, and test between each end of the
pieces of cable going to where the light fittings are.


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Third rock from the Sun.



WRT what bigwallop wrote, if he has neutral connections at his light
switches, I would suggest he also calls in an electrician! (Unless of
course he's deliberately wired his lighting circuits in a different
manner to the rest of us. (Switches should have Live ,switched Live
and Earth, not Neutral).

"Chris Holmes" wrote in message
om...
Third rock from the Sun.



WRT what bigwallop wrote, if he has neutral connections at his light
switches, I would suggest he also calls in an electrician! (Unless of
course he's deliberately wired his lighting circuits in a different
manner to the rest of us. (Switches should have Live ,switched Live
and Earth, not Neutral).

Although loop-in light fittings are "the norm" there are still instances
when sparkies take neutral as well as live etc. to the switch. May not make
it easy for the poor bugger who follows but it saves time (read money).
Richard

In article ,
Frisket wrote:
Although loop-in light fittings are "the norm" there are still instances
when sparkies take neutral as well as live etc. to the switch. May not
make it easy for the poor bugger who follows but it saves time (read
money).

I'm in favour of providing a neutral at the switch position in a room
where you might want to include 'floor' outlets for say table lights at a
later stage. It costs so little at re-wire stage, but saves a great deal
of work later.

--
*You can't have everything, where would you put it?

Dave Plowman London SW 12
RIP Acorn

"Chris Holmes" wrote in message
om...
Third rock from the Sun.



WRT what bigwallop wrote, if he has neutral connections at his light
switches, I would suggest he also calls in an electrician! (Unless of
course he's deliberately wired his lighting circuits in a different
manner to the rest of us. (Switches should have Live ,switched Live
and Earth, not Neutral).

If you have a junction box under the floor in the middle of the hallway,
with all the switch wires and a feed cable in it. You then have an after
thought of fitting some wall lights at the other side of the living room.
You'd only take a feed (Live and Neutral and Earth = One Cable) from the
junction box, to the point on the far wall of the living room where you want
a switch for the wall lights. You would then connect each lighting point
back to the feed at the switch. Life is easier that way.

I don't think you'd go to the trouble of lifting all the floors and taking a
cable from each wall light position and the new switch position, all the way
back to the junction box in the middle of the hall. Life's to short for all
that.

Or maybe "you" would. :-))


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