Recently I had a breaker box installed in an outbuilding (Homeline, 70 amps max, with 2 20 amp breakers). Power is supplied via an underground cable from the main fusebox in the basement of my house. The distance is around
100 ft and the cable is 12-2 w/ground. I wired the buidling myself (four circuits, 2 per breaker). The circuits supply 1 light and 1 receptacle in one room and 1 light and 1 receptacle in the other. However, as there was no ground bar, I tied all the grounds with the neutrals on the neutral bar. A bonding screw was included but not used. My questions:
- Does the NEC permit this? Is it safe? (I know that tieing neutral and ground together on a subpanel in the same structure is a no-no.)
- Should the building have its own ground rod? There are no connections between house and building except for the underground feed.