0

When I remodeled my home, in anticipation of replacing an old gas water heater with a new electric heater, I had a 10/3 cable run to the basement utility room. Now the heater has been delivered I discover it only needs 10/2 (black, red & ground), 30 amp. A side problem is that there's no light or outlet in the room. Could I use the redundant wire to supply lights and an outlet on another breaker? As I see it, it would involve using the ground wire as the neutral for both circuits.

3

Not in this case, because you can't put lights or outlets on a 30A circuit.

Note that also, you can't have receptacles on a circuit where more than 50% of ampacity is needed for hardwired loads.

So it could happen if, say, the numbers worked out (20A circuit, 240V/7A mini-split, then yeah, you could use both legs for 120V stuff).


Honestly, the 10/3 cable was a blunder. Water heaters don't need 3-wire feeds. You could, I suppose, fit a subpanel there, with a 30A breaker for water heater and a 15/20A outlet for lights -- however, you'd have to do a load calculation for outlets, because a water heater uses most of the feeder ampacity.

But for a subpanel feeder, for the same price as 10/3, you can get 2-2-2-4 Al feeder which is good for 90 amps instead of 30.

0
0

No and you can't use the unused wire for a separate circuit because you don't have a neutral. Just give in and run some NM 14/2 for lights and outlets.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.