Identifying neutral wires to splice into subpanel
- Thread starter euclid43
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fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
Theoretical answer: get a 200W bulb and a flasher. Hook it at the load end. Use an ammeter and search for varying amps in the neutrals.
Once identified, wirenut the hot and neutral in the panel, check the resistance at the load end of the circuit.
Good Luck!
That could be dangerous if he isn't sure where the neutral is going (or if 1 or 2 more hots are using it).
copper chopper
Senior Member
- Location
- wisconsin
do you mean that there not white or gray what all cloth wiring, and didnt you mark them when you removed them from them nuetral bar ? i need some explianation here, besides working in some old house or building i have never heard of this. you cant even check continuity to ground if there removed at the panel.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
I presumed that the circuits were in conduit, if they are in cables, it is usually not a problem. In a conduit there is a problem only if 2 or more neutrals are in a single conduit. In that case you "know" which neutrals are candidates and you know which hots can be paired.
If I have a 3 phase panel and a conduit with 2 W, 2 Blk, 2 Red, and 2 Blu, then my problem is to associate the the neutrals with the hots, and going to the load end, as far as I can tell, is the way to pair a neutral with a hot. If, as is this case, it is pretty likely that each neutral is associated with 3 hots, you don't do the wirenutting until you have identified all three hots....
It is indeed a problem. I'm had a change to 2014 NEC accepted so far that would require the identification of the neutral, hot pairings during installation.
That's something that I have always done. I also label boxes with the panel and circuit number.
Are there MWBC's or does every circuit have it's own neutral?
If every circuit has it's own neutral, then you can use an amprobe to find which neutral goes with each hot.
Just measure a hot that you want to move, see what it reads. Now measure the neutrals and find one with the same reading/ When you find one that you think may be it, turn off the breaker to that hot and see if the current on the neutral goes to 0, this will confirm it for you.
If every circuit has it's own neutral, then you can use an amprobe to find which neutral goes with each hot.
Just measure a hot that you want to move, see what it reads. Now measure the neutrals and find one with the same reading/ When you find one that you think may be it, turn off the breaker to that hot and see if the current on the neutral goes to 0, this will confirm it for you.
PEDRO ESCOVILLA
Senior Member
- Location
- south texas
shut power off, use telephone toner set up
Shut off circuit with 200w lamp & flasher.... if ammeter still has current, then you know to keep looking.
eduardo morales
Member
- Location
- del rio, texas, usa
turn off all loads, use your volt meter set it on continuity and go each wire to ground the neutral should beep.
I don't see how that will determine which circuit(s) a neutral serves on a grounded neutral system. All neutrals should "ping" to ground regardless of test points.
Simpler would be to put both the wires through the am-probe to see if the current becomes zero. If it is so, the second wire is neutral.
kwired
Electron manager
- Location
- NE Nebraska
If you are trying to pair up neutral conductors with their respective ungrounded conductors use a simple breaker finder tracer on live lines. Both circuit conductors will have signal. I would think you would want as much marked as possible ahead of time before taking things apart, unless down time is not much of a factor.
Toners or other similar methods for dead lines.
Toners or other similar methods for dead lines.
True, but in my experience live tracers are not as effective in finding the neutral conductor, compared to finding the associated circuit breaker, because at the panelboard all the neutral conductors are more solidly connected together and commonly routed in near proximity to each other. Ceating separation between neutral conductors will help, as will physically narrowing down possible mating with ungrounded conductors. The tracer should have a means of signal strength indication. If using this method, I suggest using it in combination with another verification method which does not include disconnecting the neutral conductor while ungrounded conductors are energized. ?JMO?
kwired
Electron manager
- Location
- NE Nebraska
All points you brought up need consideration, even to some extent when trying to find which breaker to shut off. A tracer with ability to adjust signal detection levels becomes more important sometimes.
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