Determining Live, Neutral, and Ground wires

[Avrohom]

I would like to verify some information I was taught today by an experienced electrician.

I asked him:"If I have three wires which I don't know which is which -- and the colors of the wires don't help -- how can I identify what's what?"

To identify live: which wire lights the tester.

Now with a multimeter set on 700 Volts, I should now see 220 volts between this wire and each of the other two wires. But which is the ground and which is the neutral?

He said, "Disconnect the main ground wire at the circuit breaker -- so that now nothing in the house is grounded. Now if I go back, the wire which shows 220 V with the live wire must be the neutral wire. And the wire which now shows zero volts with the live must be the ground wire."

Is this a good way to test?

Avrohom
Builders-of-Jerusalem.com

 

[Marvo]

.......But which is the ground and which is the neutral?

He said, "Disconnect the main ground wire at the circuit breaker -- so that now nothing in the house is grounded. Now if I go back, the wire which shows 220 V with the live wire must be the neutral wire. ........

This isn't good advice, it could leave the installation in a dangerous condition during the test and it won't give reliable results due to parallel grounding paths. To identify the neutral rather disconnect the entire circuit at the point of supply with the circuit isolated continuity test each wire between the point of supply (consumer unit) and the point of consumption (socket).

 

[Pete999]

What Marvo said

 

[amlu]

switch installation off on a main switch, get a wander lead and measure continuity between live/neutral/earth on the distribution board and the unknown cable.

working live with disconnected earth is not a good practice.

 

[Richard Burns]

Identify the line, switch off the circuit and test for dead, disconnect the circuit, join line and another cable at your identification point and then test for continuity between the wires at the board; the one with continuity that is not the line is the other wire that can now be identified by its position in the board.

 

[Avrohom]

Thank you Marvo for your words of caution!
And thank you Richard for your enlightening anwer! :driving:

I just want to clarify for myself (and perhaps others) that I fully understand what you have said:

switch off the circuit and test for dead,

== this is telling me how to:

Identify the line,

-- right?

disconnect the circuit,

== this is telling me, now that I have identified the line (the fuse to this live wire) turn off this fuse.

join line and another cable at your identification point

== this is telling me to now connect the "live" wire (which is currently dead) with one of the other wires.

and then test for continuity between the wires at the board;

== this is telling me to test for continuity between that (closed) fuse and either the whole set of neutral wires or the whole set of ground wires (in the circuit breaker box).

the one with continuity that is not the line is the other wire that can now be identified by its position in the board.

== the wire that I joined with the "live" wire must be the neutral or ground -- whichever the continuity test worked with.

Did I get it? :clap: or did I make things more confusing? :angry_smile:

Edited - Darkwood LINK REMOVED, you are not a forum sponsor so cannot advertise your company.

 

[camerabloke]

Wind up

 

[Darkwood]

Im Closing this Thread - Reason

The OP is a Handyman and clearly trying to work on equipment without basic testing knowledge, advice has been clearly given but its only showing confusion in replies.

For the safety of yourself Avrohom and others I advice you get a competent Electrician in and ignore the dangerous advice you were given by your Experienced Electrician if you intend to carry out any testing whatsoever against our advice.