Can I use another neutral in a RPM-4u? (not for the faint of heart)

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03-17-2020, 07:03 PM
imsoco

Can I use another neutral in a RPM-4u? (not for the faint of heart)

I have a job I walked into that has cove lights that do not turn on. I read 95 volts when the module is on full, or if the hot is directly connected to 120 at the panel. The neutral from the load does not connect to the neutral at the module. It is romex at the load and thhn at the module. 17,000 4 story home that has been remodeled many times. lots of splice boxes but the wires do not tone to any. If I take the neutral from a nearby receptacle I read 123 volt between it and the load hot, (when the hot is connected to 120 at the panel). Any reason I cannot use that neutral at the load? Would a neutral still need connecting to the zone on the module?
03-18-2020, 09:38 PM
randyc

Quote:

Originally Posted by imsoco

I have a job I walked into that has cove lights that do not turn on. I read 95 volts when the module is on full, or if the hot is directly connected to 120 at the panel. The neutral from the load does not connect to the neutral at the module. It is romex at the load and thhn at the module. 17,000 4 story home that has been remodeled many times. lots of splice boxes but the wires do not tone to any. If I take the neutral from a nearby receptacle I read 123 volt between it and the load hot, (when the hot is connected to 120 at the panel). Any reason I cannot use that neutral at the load? Would a neutral still need connecting to the zone on the module?

If there is an arc-fault or ground-fault on either circuit it won't work.

Modules don't like sharing neutrals. You could get ghosting (won't turn completely off) or flicker or random turning on. Especially with LEDs.

I'd be ok with borrowing the neutral for testing but you really should fix the lack of neutral at the fixture itself.
03-20-2020, 10:47 PM
imsoco

Thanks for the response.

Quote:

Originally Posted by randyc

If there is an arc-fault or ground-fault on either circuit it won't work. Modules don't like sharing neutrals. You could get ghosting (won't turn completely off) or flicker or random turning on. Especially with LEDs. I'd be ok with borrowing the neutral for testing but you really should fix the lack of neutral at the fixture itself.

This job was first installed 20 years ago, so no arc-fault. Since we could not find this splice after searching days in the attic and then on the two other floors between the load and panel, we ran a new romex from that load to another load that I moved to the same module. It will share the neutral with another load on the same module. That unknown neutral will be capped off at the panel and load.