> >
>

# Sharing Neutral Wire

#1
06-18-07, 07:26 AM
Member
Join Date: Jun 2007
Posts: 6
Sharing Neutral Wire

I am rerouting wiring in a bathroom remodel. My house was built in 1962. I have 200 amp service (sqare D breakers) with the original wiring done in metal conduit. I have 3 separate circuits coming into a junction box through conduit directly from the panel. I am rerouting with Romex and grounding to the boxes. Circuit One is 2 red (220) wires which feed a water heater, Circuits Two and Three are 2 black wires each on separate circuits and one white wire. Question - Can I use the single white wire as a neutral for both circuits Two and Three?

#2
06-18-07, 07:40 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
If and only if the two circuit breakers are from opposite legs of the incoming 240 volts. That is, the voltage between the two hot wires is 240 volts, and not 0 volts.

There are other requirements for a multi-wire circuit that must be followed as well. Unless you completely understand them, or are wiling to learn about them, I recommend you run normal (non multi-wire) circuits.

#3
06-18-07, 09:06 AM
Member
Join Date: Jun 2007
Posts: 6
One hot black wire is from circuit breaker #16 and the other hot black is from circuit breaker #34. The original wiring is in conduit running to a light junction box in the ceiling and then spliting off to the separate runs. The original wiring had the white neutral tied to both runs. When I tested the wires in the junction box, they separately tested 110 with the neutral or ground. The 2 hots tested together registered 240. If there is more I need to learn first, I am willing to.

#4
06-18-07, 09:11 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Circuit breaker numbers are meaningless. Different panel manufacturers number their panels differently.

If you measure 240 volts between the hot wires than you have opposite legs.

Describe the circuit after the panel. Does it split to two separate circuits? Does it remain multi-wire? What devices do you plan to use on it? How do you intend to wire those devices?

#5
06-18-07, 10:02 AM
Member
Join Date: Jun 2007
Posts: 6
2 hot black wires (separate circuit breakers) and one white neutral enter into the junction box from the panel. There are 2 white wires tied to the one from the panel. Those wire then split off to separate runs with one black and one white wire. They feed lights and wall recepticles in different areas. I was debating using one of the circuits as a single circuit for a new jacuzzi motor as opposed to running a complete new line. or I may run a new line anyways, but still had the question about the shared neutral. Even if I run a new circuit for the jacuzzi, I will still want to use the other for lights and recepticles.

#6
06-18-07, 10:11 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
What you propose is fine. Once you make the split to two circuits you are fine.

#7
06-19-07, 05:49 AM
Member
Join Date: Jun 2007
Posts: 6
thank you for your help

#8
06-19-07, 07:45 AM
Member
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
Given that your original wiring is in conduit, are you perhaps in a location that _requires_ conduit?

#9
06-19-07, 08:39 AM
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,798
To prevent future misunderstandings by someone not familiar with what you did I would suggest if the breakers aren't side by side you rearrange them so they are (and still measure 240v) and either use a bar to tie the handles or replace with a 240v breaker.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off