I'm On Fire wrote:There is a place on my Generac to run a ground rod to the frame. There is a grounding block with a spot open for the rod. It doesn't explain when a grounding rod is required in the manual for the generator either. I too have been wondering when it is required myself.
I think what is being described in the generator manuals is an abundance of caution to protect against two failures. For example, assume the generator frame is not connected to an earth rod at the generator. Four wires, red (hot), black (hot), white (neutral), bare or green (safety ground) are connected to the service switch, like "I'm on Fires" installation described above.
Now assume there is a insulation failure in the generator, leaking some voltage to the generator frame. The resulting current is shunted to earth by traveling along the neutral and/or safety ground. The path is up to the transfer switch, into the main panel and out to the earth ground of the service entrance. All is well. So it seems.
Now let's assume you are using a portable type generator with a male-female plug connection and you remove the plug. As you do so you will be zapped because the generator frame is no longer grounded. If there was a earth ground rod at the generator you would be protected. So there were multiple things that had to go wrong.
Your level of protection comfort is up to you, but most safety codes are written to protect even if there are multiple failures.