I plan to run PVC conduit underground from house to shed. Primary purpose is for a sub-panel in the shed – 4 wires for this. I would also like to run another set of wires "back" from the shed to the house to allow for operating a generator in the shed during power outages and bringing that power to the house. Is it allowed to put both of these wire runs in the same conduit as long as I don't violate the 40% fill rule?
Electrical – Are multiple wire runs in conduit allowed
electrical
Related Topic
- Electrical – Conduit Size for Sub-Panel run
- Electrical – does the NEC allow conduit attached to the house to an outbuilding or does it have to be buried
- Electrical – Using conduit with THHN
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- Electrical – Feeders wires to sub panel in garage with generator wires to main breaker box in the house in same conduit
- Electrical – What Wire Gauge and Conduit Size for 15a Cicruit Extension
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Best Answer
Yes, when dealing with single-phase or split-phase power, you can run up to 3 large circuits in a conduit without needing much math. But aside from all the other amp restrictions, your THHN or THWN-2 wires also cannot exceed this amp restriction:
Copper: 6AWG-60A.... 4AWG-76A... 3AWG-92A... 2-104A... 1-116A... 1/0-136A... 2/0-156A... 3/0-180A... 4/0-208A...
Aluminum: 4AWG-60A... 3AWG-68A... 2-80A... 1-92A... 1/0-108A... 2/0-120A... 3/0-140A... 4/0-164A...
Except you are allowed to round up to the next larger available breaker, so #1 Al is allowed for 100A since they do not make 92A breakers.
As long as a split-phase circuit has 3 live conductors, it counts the same as simple 2-conductor circuits. That's because neutral carries only differential current - any current on the neutral means one of the hots is carrying that much less than its rated current.