"David" wrote in message
...
I was pretty sure I was right. I needed something black and white to
prove my point. I had considered the metal path between buildings, gas
is plastic, I think water is too, but I didn't think about the coax
cable. I think we should run a groung to be safe.

We have a groung rod at guest house. Does the panel at the guest house
have to be able to disconect main power from that panel? I had thought
that a sub panel could have a disconnect at either main or sub panel.

If the subpanel was in the same building, then it doesn't require a main.
But since this supplies a separate building, you must have a local
disconnect and you have three choices. Either use a panel that has no more
than 6 breakers, use a panel that has a main breaker, or install a separate
100A fused disconnect. Some areas require that the disconnect be on the
outside of a dwelling. If this applies to you, you need either a raintight
panel or an outside disconnect. Hopefully, you can just go buy a 20 slot
panel with an integral 100A main breaker.

Because you have a 200A service, you can't run an unfused 100A tap to the
guest house. You could either tap your 200A house service and run a parallel
200A service to the guest house, or run a feeder that is protected at the
main panel to the guest house. You must have a disconnect at the guest house
in case it catches fire -- the firemen don't want to be running around
trying to find what panel feeds this building. If you're going to tap the
200A main service to feed both buildings, it becomes important to do the
service calculations because the meter base and service conductors won't be
protected from any combined overloads.

Finally, you said grounding rod. If you can't prove the grounding rod is 25
ohms or less to ground, then you need a second one at least 6' away and
bonded to the first.

--
Mark
Kent, WA