Sub Panel in detached shop

[CHI]

Saw a sub panel today in a detached shop that had the gound and neutral wires on the same bus at two locations in the panel. The homeowner, who was an electical contractor and built the shop said it was ok as the code was different when the building was built, 1997, and they were not required to be seperated because the sub was in a different building than the main panel.

I understand the codes can change, however I've never heard the "seperate building" idea.

Can anyone confirm his theory?

[Richard Moore]

If the shop panel is fed by three wires (no grounding) and there is no other possible metallic path back to the house panel(conduit, fencing, etc) then you would bond the grounds and neutrals (and the panel) at the shop. There must also be a grounding electrode at the shop.

Code would now require a 3+grnd system (4 wires or 3 plus metallic conduit) and separated grounds and neutrals (still need the grounding electrode). I don't know when the change was made but it could have been 1997.

[CHI]

Hi Richard. That's exactly what it had, a 3 wire system and a seperate grounding electrode.

Thanks for the confirmation!