[Guy Smiley]

We're on a farm and we are going to change all our secondary from overhead to underground. What the guy from the power company suggested is to move the transformer and the meter to the road. They're replacing the main line, so they'll do this at no cost to me. Then the secondary will run to a splitter box on the side of my shop, and split off to the shop, the house, and a pumphouse in the yard.

Two questions. The first is, what is the best way to isolate the box, which is metal, from the metal siding? I'm thinking just wood. The second question. The secondary is USEB, which has a concentric neautral. So when that is twisted and comes into the box, is it insulated somehow, routed so it doesn't touch the box or what? Again this is just a splitter box and not a panel.

 

[AllanJ]

The metal box where the incoming service is split for house, pump station, and shop should be bonded to ground. (Run an additional #6 copper grounding electrode conductor to the existing or new ground rods.) Inside the box, the neutral, if a separate conductor from the ground, should have insulated splices or an insulated bus bar like the hot conductors.

Provided that there is no master disconnect switch or breaker at the meter out at the road, it is okay for ground and neutral to be one and the same coming onto your property.

Some questions before you do this:

1. There have been instances where the power company or the town at a later date mandated a master disconnect under the meter. This rendered the shared neutral/ground from there to the buildings noncompliant. If you run 4 conductors 9separate neutral and ground) now then you won't run into that problem.

2. How far away is the street? By eliminating the primary coming over to the transformer on a pole on your property and running secondary from a transformer at the street instead, you could run into voltage drop problems. Power companies are not known for ensuring that the service drop, underground or overhead, is adequately sized.

Although metal building framing must be bonded to ground, aluminum or other metal siding on a wood frame house does not need to be.

 

[Guy Smiley]

Should have mentioned I'm in Canada

Thank you for the reply Allan. I know about grounding the box. The cable only has 2 hots ( insulated) and the concentric neutral which is insulated within the main cable but has to be twisted together thus stripping the insulation.( you probably know that already). All service panels, house shop etc. have their own grounding rods in place. Yes the lugs in the box are insulated from the metal box itself. My concern is that piece of bare neutral from the point is enters the box, to where it connects to the lug. It's only about 6 to 8 inches but it bothers me that it's bare.

Guy from the power company said #2 should be adequate but I went 1/0. Also, anything on the pole is taken care of by the power company so any switches etc. that are needed will be installed by them.

 

[AllanJ]

The concentric (enveloping the other wires in the service cable) bared wires will also be bonded to ground at your house, either at the splitter box or (via other wires it is connected to) at your panel.

Then the fact this bundle is bare or it touches the box is academic. It can be fastened to the box using either an insulated or an uninsulated bus bar.

 

[brric]

These are service conductors. It is quite likely the bonding of the splitter box is done through the neutral conductor just as a normal meter socket is bonded.