DIY Home Improvement Forum banner
1 - 20 of 26 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
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 (for Israel), 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? :huh:

Avrohom
Builders-of-Jerusalem.com
 

·
Civil Engineer
Joined
·
5,832 Posts
The OPS stated he is in Israel. The Israeli electrical system is 220-240V single phase power, therefore the OPS has a hot wire and a neutral wire, plus an independent equipment ground. The OPS is correct that the voltage difference between the hot wire and either the neutral or the ground wire will read 220-240V. Certainly the method proposed by the electrician to distinguish neutral from ground will work, however I am not clear where the disconnect for the main ground occurs, it could require the OPS to open the panel, which would be dangerous.
 

·
Registered
Joined
·
2,162 Posts
... He said, "Disconnect the main ground wire at the circuit breaker -- so that now nothing in the house is grounded. ...
CAUTION :excl::excl:

It may be dangerous to disconnect the earthing (grounding) conductor. If TN-C or TN-C-S earthing is used there, the grounding conductor can be energized during normal operation.
 

·
Registered
Joined
·
2,512 Posts
First, what is your earthing system, TN-C-S, TN-S or TT. ?



Normally Brown is hot, blue is neutral, and green with yellow stripes is ground. If you don't know which is which that would indicate something is wrong to begin with. In any case you will need to trace the wires from the panel. Do not, and I repeat do not disconnect anything while the board is energized, that is extremely dangerous.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #7 ·
Here walls are made out of cinder blocks. Tubes are inside the wall. I didn't check to see if I can find the junction box -- yet. Could I ask what is your plan, CLW1963?

I had another suggestion on checking these wires:

1. Determine which fuse turns off the power to these wires.
2. Turn off that fuse.
3. Now, connect two of the wires (eg. live and neutral wires)
4. Check connectivity (in the circuit breaker panel) between this closed fuse and the neutral or ground bar. You should see connectivity between closed fuse and neutral bar.

Similarly with ground wire and ground bar.

(and be careful to disconnect these two wires BEFORE turning the fuse back on!)

I tried this test in my home, yet I was surprised to see connectivity both with neutral bar and ground bar (no matter which wires I connected). What does that mean?
 

·
Registered
Joined
·
2,512 Posts
Here walls are made out of cinder blocks. Tubes are inside the wall. I didn't check to see if I can find the junction box -- yet. Could I ask what is your plan, CLW1963?

I had another suggestion on checking these wires:

1. Determine which fuse turns off the power to these wires.
2. Turn off that fuse.
3. Now, connect two of the wires (eg. live and neutral wires)
4. Check connectivity (in the circuit breaker panel) between this closed fuse and the neutral or ground bar. You should see connectivity between closed fuse and neutral bar.

Similarly with ground wire and ground bar.

(and be careful to disconnect these two wires BEFORE turning the fuse back on!)

I tried this test in my home, yet I was surprised to see connectivity both with neutral bar and ground bar (no matter which wires I connected). What does that mean?
Sounds like a TN-C-S supply.

Can you post a picture of your panel?
 

·
Registered
Joined
·
1,286 Posts
My plan would be thus..
If you have tubes with individual wires then it could be possible to go to the previous junction location and see if you can determine your wiring. Then possibly you could pull the individual wires to the location you're puzzled over and identify that way.

If at the previous junction the wires are still undeterminable, then possibly do an amp check to see what has load on it.

A ground shouldn't have load.
 

·
Registered
Joined
·
1,304 Posts
This is a do-it-yourself site, not a do-it-for-someone else site. You're doing contract work for people and you have no knowledge of what you're doing. Good day sir.
there is no diff between the two. he could have said "for myself at my other site, but this pic is the same electrical panel and service".

he would be getting "pro" advice from this DIY site, no?? what he does with it is his problem.
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #16 ·
Thank you to all who have responded to help me!!!:thumbsup:

I am a handyman in our neighborhood in Jerusalem. I am also fixing this customer's plastic water pipe (which was never secured properly to the wall. I need to add two metal corners to this pipe). And they have a drawer which keeps falling down.

Their complaint about the outlet for their fridge is that if they happen to touch their fridge while bare foot -- they get a shock. An electrician friend of ours told them the ground in the outlet is probably not connected. I haven't taken a close look to see the exact wiring situation. I just wanted a way to test if the ground is really hooked up properly -- before I go over.

I have seen a few suggestions from the experts here:

1. Examine the previous junction box

2. Do an amp check -- to see which wires have a load on it. A ground should not have a load.

3. They do have an RCD. So if I put a load on the ground wire, the RCD should trip.

How am I doing? :eek:

Avrohom
 

·
Registered
Joined
·
2,512 Posts
Thank you to all who have responded to help me!!!:thumbsup:

I am a handyman in our neighborhood in Jerusalem. I am also fixing this customer's plastic water pipe (which was never secured properly to the wall. I need to add two metal corners to this pipe). And they have a drawer which keeps falling down.

Their complaint about the outlet for their fridge is that if they happen to touch their fridge while bare foot -- they get a shock. An electrician friend of ours told them the ground in the outlet is probably not connected. I haven't taken a close look to see the exact wiring situation. I just wanted a way to test if the ground is really hooked up properly -- before I go over.

I have seen a few suggestions from the experts here:

1. Examine the previous junction box

2. Do an amp check -- to see which wires have a load on it. A ground should not have a load.

3. They do have an RCD. So if I put a load on the ground wire, the RCD should trip.

How am I doing? :eek:

Avrohom

Good, but I highly recommend an electrician try and fix the issue. This is to dangerous for a handyman to risk.
 

·
Banned
Joined
·
2,487 Posts
there is no diff between the two. he could have said "for myself at my other site, but this pic is the same electrical panel and service".

he would be getting "pro" advice from this DIY site, no?? what he does with it is his problem.
No, it's the family's problem who live there. By him doing electrical work at a home that he doesn't occupy, he isn't risking himself, he's risking other people, and that's a big difference.
 

·
Registered
Joined
·
1,286 Posts
Good, but I highly recommend an electrician try and fix the issue. This is to dangerous for a handyman to risk.
Agreed
Avro, now that we see the nature of your issue, it is well advised from a safety standpoint to have a knowledgeable professional address this situation. It's good to help, it's better to know when to pass off to someone else.
In my opinion.
 

·
Remodel and New Build GC
Joined
·
11,456 Posts
CAUTION :excl::excl:

It may be dangerous to disconnect the earthing (grounding) conductor. If TN-C or TN-C-S earthing is used there, the grounding conductor can be energized during normal operation.
First, what is your earthing system, TN-C-S, TN-S or TT. ?



Normally Brown is hot, blue is neutral, and green with yellow stripes is ground. If you don't know which is which that would indicate something is wrong to begin with. In any case you will need to trace the wires from the panel. Do not, and I repeat do not disconnect anything while the board is energized, that is extremely dangerous.

If it is simple to explain, can a pro briefly explain those different grounding/earthing systems nomenclature for a DA GC.

TIA (I under stand that... and oh yes T&A also....):wink:
 
1 - 20 of 26 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top