Grounding a house via overhead suspension cable?

[DerbyDad03]

I'm renting a vacation house on the Outer Banks of NC. It's one of those stilt built houses.

I was looking at the service entrance and noticed 3 wires going into the pipe. 2 are obviously power but the 3rd is clamped to the suspension cable that carries the service wires from the pole to the house. I followed that cable back to the pole and found that it was attached to a tap on the transformer, as was the suspension cable from 2 other houses.

From that tap, it looked like that there was a fairly small wire that ran to the same type of suspension cable which ran from pole to pole along the street.

At the house, there was no ground wire going into the ground like I'm used to seeing, so I am assuming that they are using the suspension cable as the ground wire.

Is this method used because the house is on stilts (i.e. in an area prone to flooding) or is that just a different method of running the ground, a method that could be used on any house, anywhere?

[RBM]

That's pretty standard overhead triplex cable. The bare wire, which has a steel core and is the suspension cable, is the neutral. The neutral is grounded at the poles and at the houses.

[Steve Barker]

I would still expect to see a ground at the house. Are you sure there's not a bare copper running down one of the stilts?

[DerbyDad03]

Where should I expect to find the ground at the house? There's nothing going into the ground (earth) from the meter box.

[fred.flintstone]

Unless those stilt homes have special codes, There *should* be a ground at the house. It might come off the bottom of the breaker box.

That suspension cable serves as the neutral as well as ground. The transformer pole should also have a bare wire coming down the pole to a ground rod.

[RBM]

Most likely coming out of the main service panel.

[DerbyDad03]

After further inspection, I found a ground wire coming out of the bottom of the meter box. The meter is mounted on some PT wood and there's a space between it and the house. A ground wire comes out of the back bottom and then goes up behind the meter and comes out of the side where it's tied to the cable TV ground and then goes into the earth.

It's not as big as I was expecting, maybe 8 gauge? 10? I was looking for a much larger cable like I'm used to seeing at home. Something about the same size as the suspension cable, which is why I thought it might be the ground.

Thanks for the explanation.

[gfretwell]

It is based on the size of the service entrance cable.

8ga is the minimum for 100a service, using 4ga or 2ga SE cables. A 200a service typically uses 4ga.

You do run into a conundrum. If the grounding electrode is just a rod or two you are only required to run a 6ga to it because that is all the current it will sink. Then the inspector has to ask, which rule applies.