NEC requires an electrical disconnect at the service entrance to an
outbuilding when fed from a main located elsewhere on the property. In
addition to the two hots, the subpanel in the separate structure need
to have the neutral and the ground also connected to the main panel (in
most areas of the US this means whether or not you have a separate
grounding point for the subpanel).
Now here's my question. In the newest NEC book from 2005 there is some
screwy language about being able to disconnect all of the wiring at the
mechanical disconnect. I showed this to my friend a retired
electrician who wonders if it was written in English.
Has anyone seen a mechanical disconnect that is a true (i.e. four wire)
disconnect for a structure? All the ones I have ever seen are
three-wire disconnects and don't disconnect the grounding portion.