Add that other breaker it won't hurt when you add things later. payn4school, Yes you can put those 2 15 amps together, IF and only if they are on the same phase in your pannel. If they are dif phase Kaboom. If you have a 100 or 200 amp pannel then you have 2 phases that's how you get 220. I would just run off the 15 amps, depending on how many lights you have.

Ok, here's what I run on 20 amps and pushing it. I was residential electric for 20 years. A 1000 watt hortilux eye, A 6000 btu Ac, A dehumidifier for a whole house. Vent fans in and out. A phototron and 4 , 4 foot fluro's, and 4 small pumps for hydro units and a fan to blow on plants. I'm pushing it now , so I'm running a 30 amp 220 or 221 whatever it takes. LOL.

One thing do not oversize the breaker on the wire. That is what burns you up. A breaker or fuse will blow before the wire burns for safety.
LOC NAR1958 Reviewed by LOC NAR1958 on . Electrical Question Hi everyone:stoned: I have an electrical question for you to ponder. My grow room has its own 20amp service. Im thinking about adding more lights which will push my total demand to exactly 18.9 amps. Is this a safe enought margin? I dont want to burn my house down. That would be a bad thing. Thanks for your help :rasta: Rating: 5