Bonding Screw

Hello, I had a question regarding the green bonding screw and when it is needed to bond the neutral bar. In an electrical panel of a home I inspected. The bonding screw was not installed, but was lying in the panel. would this panel need the bonding screw? It is a Squared D panel.

That would be correct for a sub-panel.

Not being there, just based on your pictures (especially the first pic) that appears to be set up as a sub-panel. In that case the ground and neutral must be isolated from each other and the neutral must be a floating neutral (no green screw). Another clue it’s a sub-panel is that there is no lug breaker to shut off power to the hot bus bars that all the breakers are attached to/recieving electricity from.

It appears from the pic that it is also a 3 phase setup but it’s hard to tell for sure as my eyes are old and pic is a little on the grainy side but, I think I see three conductors and a neutral.

Diagram is of single phase setup.

Here’s a link you may find of some benefit:

Breaker boxes explained:

While it is specifically about MAIN distribution panel set up (not sub panels) it will help explain the difference between the two.

Another link you may find of use:

No bonding until the main panel. All Square D panels have a green bonding screw (per Sqaure D). Sub (distribution) panels should not be bonded. Ditto what Joseph said.

I don’t think that’s a 3 phase. I see a 4 wire feed, two hots, neutral and a ground. What you would expect in a remote (sub) panel.

Thanks Jeffrey for the help!

Thanks Joseph for the help!! I will use this information provided to finish my report. Thanks also for the quick reply.

You are correct Dave. I mis-counted wires and I also should’ve caught/paid attention to the fact there’s only the 2 bus bar set up - not three. ](*,):oops: