What did all of these sub panel neutral and ground wire problems & electrical wiring errors mean?
When the air compressor motor was running it was producing a significant current on the compressor’s neutral circuit. The garage neutral circuit had no connection back to the main building (where it would have been connected to earth in the main panel, but because the owner had (improperly) bonded together the ground and neutral bus in his garage sub panel, the garage neutral circuit was indeed finding a path to earth through a small diameter (and thus overheated and dark) copper ground wire and a local grounding electrode. Bud, a master electrician from Minnesota points out that in the 2005 NEC there are 2 ways to connect a subpanel in a detached garage. In both methods grounding electrode(s) are required at the garage. • Hot-hot-neutral-ground are run to the garage. The neutral bar is isolated. Separate ground bar. The grounding electrode(s) connect to the ground bar. • Hot-hot-neutral are run to the garage (NO ground). This is connected like a service. A “main bonding jumper” is ins
