Recently purchased a property with several outbuildings, including a steel Quonset hut that is served by a 3 wire to a subpanel with a local ground rod. Question involves how to best handle the steel building grounding.
All the building circuit neutrals are connected to the incoming neutral and the local ground rod on the same bar. The panel is bonded with the steel building and all the circuit grounding through steel conduits. But none of that is bonded to the neutral. I know this because I recently found that one of my lighting circuit hots was in contact with the building. No breakers went but I could measure 120v from building to neutral. Thankfully no shocks.
I know ideally I should have a 4 wire with separated ground and neutral at subpanel. It’s a long run to this building and I am looking for the safest way to use the existing 3 wire. Looks to be about 1990 and 3awg cables. I understand in this application the ground and neutral should be bonded at subpanel. I’m planning to also bond the steel building to the neutral and local ground rod which seems like a major oversight in the original installation. I see this would create a problem if the incoming neutral is lost, but still seems the better approach. Under normal operation is there any reason not to bond a steel building to neutral on a 3 wire?
Thanks for help. I find this forum very helpful.
All the building circuit neutrals are connected to the incoming neutral and the local ground rod on the same bar. The panel is bonded with the steel building and all the circuit grounding through steel conduits. But none of that is bonded to the neutral. I know this because I recently found that one of my lighting circuit hots was in contact with the building. No breakers went but I could measure 120v from building to neutral. Thankfully no shocks.
I know ideally I should have a 4 wire with separated ground and neutral at subpanel. It’s a long run to this building and I am looking for the safest way to use the existing 3 wire. Looks to be about 1990 and 3awg cables. I understand in this application the ground and neutral should be bonded at subpanel. I’m planning to also bond the steel building to the neutral and local ground rod which seems like a major oversight in the original installation. I see this would create a problem if the incoming neutral is lost, but still seems the better approach. Under normal operation is there any reason not to bond a steel building to neutral on a 3 wire?
Thanks for help. I find this forum very helpful.
