120v on neutral

[topend]

RECAP - the 4 ckt fusebox is now a junction box. It contains 4 colored conductors that were connected to fuses and 4 white conductors that were connected to a neutral bar (all K&T) and 2 - 12/3 RX from new loadcenter 10' away. When one particular K&T neutral in this junction box is connected to the neutral from the new MWBC 12/3 RX, dead short. Yesterday I tried: 1) moving the shorting circuit breaker up a space (different phase), 2) - turning other three breakers off and disconnect 3 respective neutrals, 3) - rung out neutrals to determine which one belonged to respective hots. paired correct neutrals to MWBC shared neutral in 12/3 RX, 4) - disconnecting furnace, in case power surge (lightning) might have damaged something internal to cause short circuit situation, 5) - Turn all light switches off to remove from lighting circuits. Result is still the same. One circuit that was fine for a week, and now has a dead short. Customer and contractor understandably frustrated.

Rich

 

[kwired]

Use a known ground from a extension cord & test with your wiggy, but you

already knew this.

I did not say I can't tell which one is the grounded one, just can't tell which one is white.

RECAP - the 4 ckt fusebox is now a junction box. It contains 4 colored conductors that were connected to fuses and 4 white conductors that were connected to a neutral bar (all K&T) and 2 - 12/3 RX from new loadcenter 10' away. When one particular K&T neutral in this junction box is connected to the neutral from the new MWBC 12/3 RX, dead short. Yesterday I tried: 1) moving the shorting circuit breaker up a space (different phase), 2) - turning other three breakers off and disconnect 3 respective neutrals, 3) - rung out neutrals to determine which one belonged to respective hots. paired correct neutrals to MWBC shared neutral in 12/3 RX, 4) - disconnecting furnace, in case power surge (lightning) might have damaged something internal to cause short circuit situation, 5) - Turn all light switches off to remove from lighting circuits. Result is still the same. One circuit that was fine for a week, and now has a dead short. Customer and contractor understandably frustrated.

Rich

I think you may have some problem unrelated to what you changed. Find out what loads/outlets do not work when the breaker is open and start investigating them. Also make sure of your 4 circuits you mention you have no interconnection between any of the circuits. As I have said earlier you should not have any continuity between any conductors except one hot and one neutral with a load connected to them of each circuit. Continuity anywhere else means crossover connection somewhere between circuits and it may have originally been connected in a way that this crossover did not result in a short circuit, but was still not right.

 

[mlnk]

Why are you running multi-wire circuits when you know they will not work with an AFCI breaker, which is required in my county when you change a panel. It may not be required by your AHJ now, but it may need to be installed in the future.
My new commandment: Thou shalt run no multi-wire circuits...

Also, a poster above said proximity tester, is this the same as an inductive hot stick?