But in that case, you need to have an equipment grounding conductor in the feeder. Otherwise you have no low-impedance grounding path back to the service panel. The pre-2008 rule was that if there was a continuous metallic path, you needed a 4-wire feeder. That was acceptable pre-2008. After 2008, you always need a 4-wire feeder and ground/neutral separation regardless of metallic paths. [:-thumbu][:-thumbu][:-thumbu][:-thumbu]