Basic wiring advice needed

[William Hinshaw]

This may be a little OT, but I sure could use some help. I've built a 12x24 multi-use shed, mainly intended to store my hardwood boards and increase accessibility to those that always seem to be on the bottom. The wood racks look great. In any case, I'm wiring it for lights, receptacles, exterior lights and to feed power to a garden pump.

I have a Siemans breaker panel with a 100A main breaker installed. I would like to have a main breaker handy in the shed. There are two vertical bus bars which are presently connected by a removable insulated strap that crosses the midline. One of these vertical bus bars has a green screw that, if turned, will bond that bar (and the other one too if the strap is left in place) to the metal case.

The connection to power, which once went to a panel in a mobile home now replaced by the shed, arrives underground from the meter box (my meter is on a pole remote from the house and I made the large temp panel there permanent because the service is split there for several uses) in the form of *four* insulated #4s: two hot wires, a neutral and a ground. These are controlled by a 100A 220V breaker at the meter panel.

At the shed, am I supposed to isolate the neutral bus bar (by removing the strap) and connect my neutrals all there and then ground the case with the green screw and connect all my grounds to the now separate ground bus bar? This would replicate the arriving connections and seems right to me, but what do I know?

Any advice will certainly be appreciated.

Bill

[Igor]

Someone here might have an answer. Personally, some of what you wrote seems contradictory to me - at least confusing. If no answer here, you might try alt.engineering.electrical and/or alt.home.repair where some electricians hang out.

In general, your elec service should only be grounded once, at the main panel, and subpanels need to tie back to that ground -- so there is no tie bewteen the neutral and the ground in subpanels. If you have more than one drop after the meter -- i.e., more than 1 "main" panel -- you are well beyond me. Good luck.

[BRuce]

simple answer, yes.

all the sub panels and sub sub panels should have the ground and neutral isolate. this prevents "ground loops"

BRuce

William H> This may be a little OT, but I sure could use some help. I've built a 12x24

[ranck]

I *believe* from what you have described that you should bond the ground and neutral together and provide an earth ground rod at the entrance point to the shed. My understanding of the NEC is that with sub-panels in detached outbuildings you can use an entry-point ground rod for the outbuilding that is not tied back to the main house ground. I think that is what I would do in this case. Check with your local inspector to be sure this is legit, though. And, do get this inspected.

Bill Ranck Blacksburg, Va.