Electric Service to new Bldg.

I ran FOUR, not three #2 Al USE conductors. The ground and neutral are separate conductors; naturally ground and neutral are separated in the panel. (There's a screw for that purpose that you need to remove in the panel.) I think you will find #2 copper to be very expensive (if you can get it at all). #2 USE aluminum is relatively inexpensive and you can get it at Home Depot.

I have a 100 amp service disconnect at the meter. Neutral and ground are tied together there. The inspector complained about the existing single ground rod at the house, so I added a second rod to make him happy.

At the shop, there are two ground rods at least six feet apart. I have two yard hydrants at the shop; I thought the inspector would let me use them as grounds, but he didn't go for it. Not only did I have to add the ground rods, I still had to bond the hydrants to them. For the hydrants, he dinged me for using non-direct burial clamps, so I had to special order direct burial clamps. (I didn't want to have clamps and ground wires above ground.) In your case, it's important to understand that the second ground rod isn't for the siding; it's a requirement to have two rods even for an all-wood building. All grounds must be bonded together; I think #6 copper is the minimum. I know that an all steel building must be grounded; I'm not so sure that there's any requirement to bond metal siding on a wood building to ground.

My recommendation is that you check with your local inspector to find out what will make him happy.

If the ground wire is bonded at more than one place, should something happen to the nuetral wire along the way, you will never know it and the ground wire will be doing that job instead. However, this will mean current is always 'there' on every metal surface throogh-out your electrical system. Not good!

The odds of your nuetral wire going bad is kinda low, but the results of it could be a real bad thing.

The nuetral & ground wires _are_ connected in your one main box, as both of these wires do need to be solidly connected to earth, and that one place works well, but only one place. They both connect to earth there, but don't affect each other because that is the only spot they connect.

Else you have made the neutral & ground wires parellel to each other, & interchangable. You don't want them interchangable.

This is not an electrician's explination and might not be all technically correct; but hopefully paints a picture of the situation.

--->Paul

The neutral is an insulated current carrying conductor just like the 120V line1 and the 120V line2. Line3 too if it's a 3 phase Y connection. The secondary side of the service transformer can not be allowed to float without a reference to true earth for safety. If you want to get a real electrical shock, just open the neutral when it�s under load and touch it. Now mix in open/poor grounds and an open neutral but a bond between the neutral and ground conductors? Somebody, something is going to get burned, hurt or killed sooner or later. The Neutral's voltage with respect to true earth ground is kept as low as possible. This is via a bond, one bond and one bond only. As close as possible to the hydro service grounds/main distribution panel/hydro meter. Since no conductor is perfect and operates without voltage drop. And no grounding system can hold the hydro service at absolutely true earth potential. You cannot tie the neutral with up to 2% voltage drop at the end of its run at a load(s). Tying the neutral and ground together will raise the grounding systems voltage. Due to VD on the grounding system as well and the ground rods. The end result of mixing or bonding the ground and neutral together anywhere except at the hydro's main service. Is that everything bonded to the ground system. E.g. door frames water pipes, livestock water basins, milking equipment, feeding equipment, stalls etc. These items that are supposed to be at earth potential. They now can easily have 1,2 even three volts on them. 1,2 or 3 volts sound like no problems to people and it very rarely is. However when standing on four hooves in wet conductive "stuff" and touching something with your tongue that is 1,2 or 3 volts..... ..... . Try testing a 1-1/2 volt battery across your tongue..... .... Even if you don't have livestock, your service can shock somebody else's herd down the road. So if you are done some farmer fixes like running something 120V on a 240V power supply with no neutral and using the ground as a "neutral". You are making a problem. So no connection(s) between the ground or neutral system except at one place. And the bare wire is to only conduct fault current or dissipate induced voltage. Induction sources can be lightening storms, nearby high voltage lines, static etc. For those of you how think a 120V motor has two grounds or something. Dead wrong.

As far as grounding is concerned, I would bond to about everything possible and avaialable such as the driven made earth ground rods (1 or 2 as locally required) PLUS any metallic water pipes or metallic gas lines etc.

The No 2 conductors (depending on class n type of insulation) should suffice HOWEVER if youre gonna use high amperage loads/devices and voltage drop is an issue, you might wanna consider bumping it up to No. 1

Underground direct buried feeders ought to suffice but in conduit under driveways etc and protected by conduit where it comes up out of the ground into your building.

I would have a main disconnect at the panelboard in your building.

John T (Long retired electrical engineer n rusty as an old nail on the NEC)