View Full Version : Are multiple circuits allowed in one junction box?

November 11th, 2002, 05:31 PM
I am rewiring a bathroom which had numerous code violations. I am adding a ceiling heater/fan (600 W) which is tagged for a maximum 15A circuit protection allowance. I am also replacing a non-GFCI outlet with a fault-protected outlet which I understand needs to be on a separate 20A (12ga wire) circuit (so a hair dryer, etc. can be used).

I want to mount a two-gang box which will contain the time switch for the heater/fan and also the GFCI receptacle. Is it permitted to have 2 different independent circuits in the same box and also to run the wires of the two circuits to the box in the same conduit?

This occurred to me after I had an instance where I cut power to a ceiling fixture to repair it and (painfully) found other wiring stuffed inside the box that was both still live and in poor condition.

I am aware that it is not permitted to run wiring of a single circuit to a given outlet box or junction box through in multiple conduits. That is, a circuit is allowed to branch out to serve its different loads, but the branches cannot be brought back together. I also assume that wiring of a foreign circuit could pass through a junction box without connecting to anything in it. But I haven't seen any statement on the case I described above.

Many thanks,

November 11th, 2002, 08:02 PM
Concerning bathroom receptacle GFI protection there is no restrictions to my knowledge that prohibits other circuits whether also GFI protect or not GFI protected from occupying the same box or conduit. You can do as you wish.

IF this were related to swimming pools, hot tubs, or fountains then I would have quoted a violation. Rules for these GFI circuits require any conductor sharing the same box or conduit to also be GFI protected where these water related circuits are GFI projected.

Concerning bathrooms, outside convenience receptacles, and kitchen counter receptacles that are required to be GFI protected there is no such rule requiring other wires in the same box or conduit to also be GFI protected. YOu are fine with your plan

Good Luck