Three rooms and three switches

[OldracerJones]

I'm starting to wire my offices inside my metal building. I have a few questions if you have time.

-installing a sub-panel. 50 amp breaker to sub, 8 gage, 2wire plus ground to bring 120v to sub-panel. 25foot run. My question is if I only need to bring 120v over, is this wire okay. My book shows 2 hots and a common with a ground for 240v, so now I'm questioning if I need 8 gage 3 wire plus ground.

- I have 3 rooms, each with a separate light switch, single pole. In two of the rooms there is only one ceiling fixture, in the third room there is two fixtures. My question is, do I need to run a separate circuit for each room or can I run one circuit for all three rooms?

Thanks for any input.

 

[pattenp]

First off you need 4 conductors to the sub, 2 hots 1 neutral and 1 ground. Next thing, what type wire are you using to feed the sub? If you are using NM then it needs to be #6-3 w/ground.

You can run one lighting circuit for the three rooms, provided the combined amps of all the lighting does not exceed 80% of the amp capacity of the circuit.