How to tell difference between Loaded Neutral and Hot Wires

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Cletis

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Was messing around with a 5 gang box that had a combination of receptacles, single pole switches and three way switches. The owner cut it out and all I had was a mess with 6 Romex (4-14/2, 2-14/3) so off I went to try and convert it back to just a single gang receptacle box and make all the other lights come on by their switches. As I started from scratch I ran across a white that read 120V to ground and it also lit up then cv tester. Well, I had a feeling it was an open neutral and still think it is. But, what I'm curious about is how do you determine a wire is the hot or a loaded neutral by simple meter tests ? I didn't have time to finish and must go back now this is bugging me. Any ideas ?
 
Cletis said:
Was messing around with a 5 gang box that had a combination of receptacles, single pole switches and three way switches. The owner cut it out and all I had was a mess with 6 Romex (4-14/2, 2-14/3) so off I went to try and convert it back to just a single gang receptacle box and make all the other lights come on by their switches. As I started from scratch I ran across a white that read 120V to ground and it also lit up then cv tester. Well, I had a feeling it was an open neutral and still think it is. But, what I'm curious about is how do you determine a wire is the hot or a loaded neutral by simple meter tests ? I didn't have time to finish and must go back now this is bugging me. Any ideas ?
Click to expand...

How do you know the white wasn't a switch loop? What did the black that went with it read on the meter?
 
Cletis said:
The whole box had 2 circuits in it. from that white to the black in same Romex read 0V. From "That" white to ground read 120V
Click to expand...
The black in the same Romex could very well have been going back up to the fixture. The switch leg LB suggested. Open neutral at the fixture or non functioning lamp would give you zero volts.

We were not required to mark those white sw leg wires back when. You were just supposed to know.
 
Step one for this kind of troubleshooting is to get a solenoid voltage tester, which uses enough current to not respond to induced (phantom) voltages.

Step two is to plug an extension cord into a known-properly-wired (non-GFCI-protected) receptacle. This gives you references to test against.

Step three is, as suggested above, to find the other end of this cable and see what it's connected to. It's either an open neutral or a switch feed.
 
LarryFine said:
Step one for this kind of troubleshooting is to get a solenoid voltage tester, which uses enough current to not respond to induced (phantom) voltages.

Step two is to plug an extension cord into a known-properly-wired (non-GFCI-protected) receptacle. This gives you references to test against.

Step three is, as suggested above, to find the other end of this cable and see what it's connected to. It's either an open neutral or a switch feed.
Click to expand...

Several years ago, Larry shared his extension cord secret, when other Masters on this forum enjoyed punishing the gullible and reprimanded each other for giving away good advice. Moderators at the time may have banned him for doing it, but I've been using that trick ever since.
 
LarryFine said:
Step one for this kind of troubleshooting is to get a solenoid voltage tester, which uses enough current to not respond to induced (phantom) voltages.

Step two is to plug an extension cord into a known-properly-wired (non-GFCI-protected) receptacle. This gives you references to test against.

Step three is, as suggested above, to find the other end of this cable and see what it's connected to. It's either an open neutral or a switch feed.
Click to expand...

Great tip, I'll report back
 
If open neutral and you have voltage on it, you are on the supply end. If the accompanying black wire is disconnected on your end you shouldn't have feedback on the white because of open neutral. That is if things are done the way they should have been done, you still could have open neutral path from something that is "unconventional". Having a "hot" white conductor like that does increase the chances it is a switch loop.
 
Step Four?

Step Four?

LarryFine said:
Step one for this kind of troubleshooting is to get a solenoid voltage tester, which uses enough current to not respond to induced (phantom) voltages.

Step two is to plug an extension cord into a known-properly-wired (non-GFCI-protected) receptacle. This gives you references to test against.

Step three is, as suggested above, to find the other end of this cable and see what it's connected to. It's either an open neutral or a switch feed.
Click to expand...

Larry, Please expand on this. How is the solenoid tester and extension cord used?
 
Greg1707 said:
Larry, Please expand on this. How is the solenoid tester and extension cord used?
Click to expand...
It is plugged into a known working reference point, all you are doing is extending that reference point to where you are troubleshooting. You still need to know how to decipher the readings you get.
 
growler said:
Sounds like a switch loop.

Easy way to make sure is to touch the white and black and see which light comes on. Now you have it identified and can mark it.
Click to expand...

He said it measured 0V to the associated black though. That might mean the lamp is out, or maybe switches a receptacle with no load present.

Could even be a three way "traveler" set in the cable in question, and a 4 way switch is supposed to be installed in this box.
 
kwired said:
He said it measured 0V to the associated black though. That might mean the lamp is out, or maybe switches a receptacle with no load present.

Could even be a three way "traveler" set in the cable in question, and a 4 way switch is supposed to be installed in this box.
Click to expand...

Thanks I missed that one about the 0V from white to associated black.

I still think it a good place to started. Could be a ceiling fan or light kit with pull chain switch in off position.

You really need some idea of what all those switches could possibly control to start with. If a switch box is by a front door I normally assume one switch is for the exterior light (as required). Unfortunately we don't know the location of this switch box.
 
growler said:
Thanks I missed that one about the 0V from white to associated black.

I still think it a good place to started. Could be a ceiling fan or light kit with pull chain switch in off position.

You really need some idea of what all those switches could possibly control to start with. If a switch box is by a front door I normally assume one switch is for the exterior light (as required). Unfortunately we don't know the location of this switch box.
Click to expand...

Switch by front door can easily be for receptacle(s), inside or outside, inside lights, outside lights, outside lights away from the building - those post lamps at the end of the drive... possibilities are sort of unlimited.
 
Greg1707 said:
Larry, Please expand on this. How is the solenoid tester and extension cord used?
Click to expand...
Okie-dokie. The idea is to compare the wire in question to the two (three if you count the ground) in the cord, and look for expected vs. unexpected results. For example, a wire that is hot will test as hot to the cord neutral (and ground) and either nothing or 240v to the cord hot, depending on which line each (wire vs. cord) happens to be on.

A wire that is grounded will test as hot to the cord hot, while a wire that is floating will test as nothing to any cord terminal. A tripped breaker will show the hot as floating (unless loads are still connected, in which case the hot will test as grounded) and the neutral grounded. If a GFCI upstream has tripped, both terminals will show as floating.
 
Ideas

Ideas

This thread is awesome. Let me preface again whats going on and the goal.

I had 2 - 4 gang boxes (upstairs and downstairs). Someone basically just chopped all the Single poles, 3 and 4 ways, and rec out without any marking. I just needed the chopped out box made into a basic receptacle and make the other 4 gang box operate all the lights. On top of all this it was wire "Very" unconventional". What I mean in 1 of the 14/2 Romex one of the whites was an open neutral but the black was used to feedback to the other 4 gang box to power all the switches. Anyhow, my science experiment is to use multiple meters and my brain to hook this all together again and make it work "Without" cheating and taking the other 4 gang box apart (if possible) and ring everything out and just fix it. I'm not sure yet if this is possible or not due to the light fixures and odd configurations. Also, the lights that I need to make work again are 2 sets of motion sensors floods outdoor, porch rope lights plugged into a switched outdoor outlet and 8 indoor led can lights. One thing of note is I'm not sure how to determine the resistance of led drivers yet (if there is a way like a bulb) and also bypassing the motion without putting tape in it to get a resistance? I'm guessing this is futile ? Anymore troubleshooting tips are appreciated. I"m going back Sunday with my note pad and I'm going to do experiments with each wire (there are 10) and do resistance, high impedance meter, wiggle and record results. If I get too flustered I'm just going to cheat and take 4 gang apart and make it work and get paid.
 
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