Existing Electrical in House is Concerning

First, thank you everyone for the amazing support out there! I will make my question brief:

I have purchased a home and am expanding. I would like to add an 8-light controller. I will be using the existing 80A 240V that was for the electric range (new range is gas). However, the wiring used for the outlet is 8 AWG and runs approximately 25-30'. This seems much too low for an 80A breaker! The lighting controller will be closer--approximately 15-20' from the breaker, but as short as 8-10' if absolutely necessary for 8kW.

I was hoping to use the existing wire to avoid servicing the panel, but am concerned that 8kW of lights is too much. Was this incorrect for the electrician who wired the range outlet? Should I increase this wire size? My only alternative is to run (2) alternating 4kW 12/12 rooms.

The breaker is way over sized. At best, and if the wire is THHN, it's only rated for 55 amps. You could just replace the breaker with a 50 and go to work if you want to. If you balanced the load, you're only talking 33 amps per leg, for lighting alone of course. Add in all the extras, if this will be your sole source of power to the room and it might be a little light in the long run. If your only talking 15-20 feet of wire, it wouldn't be too pricey to just upgrade the wire and keep the breaker.

Whoever that electrician was, he wasn't a competent electrician. I'd look all that stuff over before I relaxed about using it.

Thank you, droopy107!

Looks like I will have to replace either the breaker or the wire, so I may as well open the panel and do everything the best way possible. I had originally planned on running the lights on 240 and everything else on 120, but if I'm running wires, should I consider fans, pumps, etc. for 240?

6 gauge wire for 50 amps.

Carolina Dream'n said:

6 gauge wire for 50 amps.

Click to expand...

Run the 50amp 2 pole with the #6....buy a sub panel and put another 50amp 2 pole breaker as the main breaker....now run 120 volt pumps and fans....if you are buying ballast new buy 240 volt....now run 1000w for 1 20amp breaker...plug each light into the controller.
600w 240 you can use 2 lights on 1 20 amp breaker.

Check the tightness of the breaker screw to wire connect and make sure they stay tight over time the screw will back off...a burn wire will be noticed here.
Also if a breaker keeps blowing replace and go again

if your running 8k in lights your going to want more than a 50 amp sub panel

- Jiji

You'll need 50a at 220v dedicated to the light controller. 80a should cover lights, AC, de humidification, and and other 120v needs (fans, pumps ect) no problem. i would run 4 gauge copper from the existing 80a breaker in panel to a sub panel right next to light controller. then youll have a panel just for ur grow and nothing else.