I am still a bit confused about bonding straps or screws in the main panel. I have been told that bonding should only be done at the main electrical panel. I have had an electrician with years of experience tell me it is not a big deal. I have also heard from an inspection company that has been around for over 25 years that they never write up if a screw/strap is missing or in the wrong place. Thoughts?
Actually it is very important. The NEC term for that screw or strap is the main bonding jumper (MBJ). Its function is to bond the metal cabinet of the panel to the neutral conductor and this will provide a low resistance path for any ground fault current imposed on the metal parts to return back to the source on the neutral. During a ground fault there is very little resistance beyond the resistance of the metal parts and the wire. This allows for a very large amount of current flow which will cause the OCPD (circuit breaker or fuse) to open.
So, this panel I looked at today had a main disconnect on the outside and the main panel in the garage. There was a bonding strap on the panel in the garage. Should the strap be removed because technically the panel in the garage is like a sub panel?
Yes, the MBJ is installed only at the location of the service disconnect which in your case is on the outside. A sub-panel is fed by a feeder and the neutral and EGC’s are isolated from each other at a sub-panel.
Thank you Robert!
FYI: You can’t have both
Much better to describe the panels as service and panel or distribution panel. Avoids the confusion if a non-service panel has a main breaker.
I agree that the terminology is all over the place. Although not officially recognized I prefer the use of the terms service and sub-panel.