Gentlemen, I have a question about a bonding scenario I saw today. Working in a new hospital, I walked by a row of sub panels, and the bonding caught my eye. The first panel in the row was feeding the next, and had a 2" ridgid nipple between them. On the end of each side was a bonding bushing with the wire just going through the nipple and bonding on each side. It was a punched hole, but I thought the wire should extend to the grounding bus.
In the electrical room, I looked at the panels in there and I saw a few panels with the same set up, but instead of the wire just going from bushing to bushing, they had on side bonded to the panel, and nothing on the other side. I can't find anything in the book that says this is wrong, but it just looked wrong. Maybe its just another way of doing it. Any ideas? Gary
Grounding bushings connect a wire to the pipe. By connecting two grounding bushings on opposite ends of a nipple together, they were merely bonding one end of the metal nipple to the other end. Maybe they thought this was required because of the requirement for redundant grounding (bonding) in health care facilities. In any event what they did was useless. A green wire from one panel's ground bus to the next panel's ground bus would be redundant grounding (bonding) with the locknuts and metal nipple the other bond. What was done falls a little short.