Combine neutrals from 2 circuits


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Old 03-24-23, 09:26 AM
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Question Combine neutrals from 2 circuits

Can you connect one 14/3 neutral to 2 neutrals from different circuits?
 
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Old 03-24-23, 11:52 AM
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Not proper to combine or connect that neutral to neutrals of other power feeds (e.g. different branch circuits) entering the same outlet box or junction box.

From any 120 volt load in the electrical system (light air conditioner, TV, etc, also any receptacle.) there must be exactly one possible neutral conductor path back to a breaker panel Also exactly one hot conductor path.

Okay to split the neutral of the incoming 14-3 feed cable to provide a 14-2 (say, using the red from the feed cable) to continue off in one direction and provide another 14-2 (say, using the black of the feed cable) to continue off in a different direction. In this example, the two 14-2s continuing on are considered parts of the same branch circuit (a multiwire branch circuit, with 240 volts between red and black) while downstream of the split the two 14-2s behave as separate branch circuits.

Now, you do combine all of the ground wires from the various cables entering the box.
 

Last edited by AllanJ; 03-24-23 at 12:30 PM.
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Old 03-24-23, 01:00 PM
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a multiwire branch circuit, with 240 volts between red and black
By code requires a 2-pole circuit breaker or two adjacent single pole breakers with handle tie.

​​​​​​​downstream of the split the two 14-2s behave as separate branch circuits.
But being protected by the 2-pole breaker a fault on either will disconnect power from both.

Just something to be aware of. Could make troubleshooting difficult.
 
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Old 03-24-23, 02:19 PM
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Welcome to the forums.

Based on your question.... the answer is no.
 
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Old 03-25-23, 01:30 AM
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As stated, no you can not.

However, a MWBC (multi wire branch circuit) does allow for a shared neutral.

Research MWBC. It is very specific. You will learn why it is dangerous to share a neutral but allowed in a MWBC.
 
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Old 03-25-23, 04:14 AM
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If the 2 hots were not on opposite legs of the panel there is potential to have up to twice the neutral current on the conductor.
 
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Old 03-27-23, 09:38 AM
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Thank you all!
pcboss: The 2 circuits are #7 and #9 on the circuit panel (both on the same side of the panel). Does this mean they are on the same leg and therefore a problem? Thanks
 
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Old 03-27-23, 10:13 AM
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You need to measure voltage (using a voltmeter) between the two breaker screws and get about 240 volts.(And between one breaker screw and the neutral bus bar (terminal strip) measure about 120 volts.)

Usually but not always two breakers one right above the other and both on the same side of the panel will give 240 volts which means they are on opposite legs and usable for this 14-3 cable..Get and install a handle tie over the two breaker toggles, or better, replace the two breakers with a (15 amp) double wide double breaker set.

If you get little or no voltage between the breaker terminals (and 120 volts either terminal to neutral) you must not use those breaker slot positions (they're on the same leg of the system) to power your 14/3 cable.
 

Last edited by AllanJ; 03-27-23 at 10:26 AM.
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Old 03-27-23, 02:25 PM
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Can you connect one 14/3 neutral to 2 neutrals from different circuits?
This needs clarification as everyone is thinking something different.
Do you have a red wire on one breaker and a black wire on the other breaker ?
If yes.... you have a MWBC where the neutral leaving the panel is shared by the black and red circuit.
In that instance... the single white neutral will be used for two circuits.


 
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Old 03-30-23, 09:31 AM
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Thank you all, again. Much appreciated.
I am going to replace the 14/3 with 2 14/2s which will separate the circuits. TY
 
 

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