Two circuits in 2-gang box?

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Old 01-26-18, 11:31 AM
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Two circuits in 2-gang box?

I'm planning a kitchen remodel for my brother. Can I put two receptacles in a two gang box and have two separate circuits in that 2-gang box?
 
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Old 01-26-18, 11:53 AM
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So you want each receptacle on it's own circuit?
This is pretty common for dishwashers and garbage disposer wiring.

You normally feed the two receptacles using a multi-wire branch circuit. You would run 12-3/with ground to a 20 amp double pole breaker in the panel. The double pole breaker assures both circuits will trip at the same time.

The neutral is shared by using 2 pigtails, one for each receptacle. The black wire would feed one receptacle hot and red would feed the other.

If you use a mwbc, do not use the receptacle screws to extend the neutral to the second receptacle. Connect 2 pigtails to the incoming shared neutral and connect one pigtail to each receptacle. That is required when splitting the circuit.
 
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Old 01-26-18, 12:03 PM
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The double pole breaker assures both circuits will trip at the same time.

Common trip of both circuits in a multiwire branch circuit is not required by the NEC, only common disconnect of the two circuits is required. That is why the preferred method is to use an approved handle tie across two adjacent single pole breakers for the multiwire branch circuit rather than using a 2-pole breaker. When using a handle tie troubleshooting a problem that has tripped one breaker is much easier. If a 2-pole breaker was used additional troubleshooting is needed to determine which circuit has the fault.


Can I put two receptacles in a two gang box and have two separate circuits in that 2-gang box?

Yes. Connect all ground wires together, but DO NOT connect the neutrals together unless this is a multiwre branch circuit with a shared neutral.
 
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Old 01-26-18, 12:06 PM
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Thanks! The 20A double pole breaker makes sense; never occurred to me. My brother suggested it and I was visualizing someone killing power to one receptacle and reaching into the box thinking everything was dead!!
 
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Old 01-26-18, 12:17 PM
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"Yes. Connect all ground wires together, but DO NOT connect the neutrals together unless this is a multiwre branch circuit with a shared neutral."

OK, you lost me a bit on that; sorry, I'm not all that familiar with electrical beyond the basics. Are you saying I can't use a 12/3 and have a common neutral? I should run two 12/2's with the handle tie across two adjacent breakers? Simple trouble shooting sounds smart to me.
 
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Old 01-26-18, 02:08 PM
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I can't use a 12/3 and have a common neutral? I should run two 12/2's with the handle tie across two adjacent breakers?
If you wire it as MWBC (multi wire branch circuit), use 12/3 with shared neutral. And either 2 pole breaker or 2 single pole breakers with a handle tie.

You may also run 2 12/2 cables. In this case, do not connect neutrals together in the junction box. All ground wires get spliced.
In this case, handle tie is not required. But, don't forget that you have to turn off 2 breakers to cut all power to the junction box. Any electrician should be smart enough to see that when they open the box.
 

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Old 01-26-18, 02:15 PM
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In this case, handle tie is not required. But, don't forget that you have to turn off 2 breakers to cut all power to the junction box.
If you decide to run two individual breakers, I would use a Sharpie marker and print on the inside of the cover plate "this box is served by two circuits" or something to that effect.
 
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Old 01-27-18, 04:08 AM
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Thanks all for being patient with me. Still not sure which way I'll finally go, but at least I understand what I can do. But I do know for sure if I go with 2 separate breakers and 12/2's, the breakers will have a handle tie. The possibility of having one dead and one hot circuit in the same box just doesn't sound safe to me.
 
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Old 01-27-18, 09:33 AM
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As electricians we install many circuits in the same junction box. As long as all wires are insulated and caped off it is OK.
 
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Old 01-29-18, 06:32 AM
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What was said earlier was that each neutral must serve only the items (receptacles, etc.) served by the matching hot wire. For a multiwire branch circuit, the neutral serves both the red wire and black hot wire in the same cable and multiple pigtails (jumpers) may be attached to that neutral to go to receptacles served by either of those hot wires.

For the separate 12/2 cables you will have two wire nutted bundles of neutrals with no interconnection, one for each cable's neutral and pigtails (or a neutral connected directly to a receptacle also receiving the black wire from that feed cable with no wire nuts or pigtails).
 
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