DaveG wrote:

I think it is true, he appears to be installing a sub panel in a building
which is unattached to the building that houses the main panel, and these
buildings do not have anything like metal pipes running between them. If
this assumption is true, then the NEC requires the installation of a ground
rod, and requires the neutral bus be bonded to the ground bus.
If my assumption on the setup of these 2 building is wrong, then I stand
corrected. This is why the original poster needs to check with the local
electrical authority in his area. Get the right info based on your
particular situation, and go from there.
Dave

Local codes vary. I'm in Seattle, and when I bought this place, my
inspector didn't like the cheesy little subpanel in the garage, where
neutral and ground were bonded. He said is was a code violation. That
detached building also has other 120V circuits to it that aren't on that
panel, as well as phone, copper water supply, and cable. It has ground
rod. I plan to fix it eventually by running a larger feeder with a bigger,
up-to-code panel.

Dave--I'm pretty sure it used to be okay to bond G-N as long as there
were no other conductors and as long as a good ground rod was in place.
Codes change quickly and geographically so it pays to check with an
inspector or local electrican.

My point was just that it is always safe to run the 4 wire feeder, a
ground rod (or 2) and then use a separate ground bus in the subpanel.

There may also be an issue with needing a service disconnet depending on
the number of curcuits served by the panel.

This subject has been discussed at length in this and other forums.
Any one curious what sort of "bad things" can happen when your neutral
and safety ground (i.e. equipment cases) become live due to a fault can
find out from those more knowledgable than myself.

Cheers All--Jeff Dantzler