Basic wiring

Hello, I'm wiring some lights off a 20 amp circuit. I am using 12 guage wire, but am unsure if I need to use 12guage grounding wire. A co-worker had told me that 14 guage would be fine. Any suggestions?

 

It would probably be fine in lighting circuit and they used to allow a smaller wire in grounds because direct shorts can draw hundreds of amps instantaneously, however, I believe modern codes call for the ground to be equivilent to the conductors in branch circuits. Remember the purpose, to provide a low resistance pathway back to the panel to carry enough current to trip a breaker or blow a fuse instantly in the event of a short. The better the wire the better it is going to work. When you say provide a wire are you using cable or pipe? The cable (romex) should have the wire in it and if it is pipe that can be the grounding conductor also.

 

Sberry27 is talking about the grounded wire, not the grounding wire...there is a difference. Your grounded/white wire carries current back to your panel and your grounding wire carries current to earth in the event of a fault. Either way the NEC says it must be a 12 gauage wire if you are on a 20 amp circuit. Also remember that in residential you are only suppose to load the circuit to 80% max or 16A for a 20A circuit.

If you are using standard NM cable then all the wires will be either 12 or 14 gauage and if you need to tie a grounding/green wire to the bare wire in your cable for extension then it should be a 12 gauge wire.

JJRICK

 

I am quite certain that sberry was indeed talking about the grounding wire.

 

Thanks for the reply. I am using bx, and planned to run 12 guage, (including ground) through it. I wanted to run a ground wire to connect to lighting fixtures. This brings me to another question. On another 20 amp circuit, there was a 15 amp light switch, and 15 amp receptacle. This concerned me, so I replaced them with 20 amp rated devices. Was I correct in doing so?

 

You were correct to do so. But you would have been also correct if you had not done so. 15-amp receptacles and switches are allowed on 20-amp circuits.