"Jim Miller" wrote
Another question...

We have underground utilities in this neighborhood. The box on the side
of my house where the utility feed arrives has an approximately 1ft
section buried. There's actually a grade line marked on the side of the
box which I presume is a "do not exceed line. The service no doubt
enters through the bottom of this box.

I've dug carefully on one side of the box and so far haven't found a
ground rod. Before I continue digging I have a question about the
ground rod location.

Is it possible/typical that the contractor would put the ground rod
underneath the service entrance box in cases like these? If so it would
probably be pretty difficult to get to it.

Would driving another rod within a foot of the service panel be
adequate? (of course taking care not to penetrate the AC mains!)

I noticed the phone guy just put a hose clamp on the big metal
compression nut that has one side of the mains leading into the house
and put his ground under that. This is on the outside of the service
entrance box outside the house.

Would grounding through a similar compression bond to the box be a
reasonable alternative?

tnx
jtm


Hi Jim,

The buried conduit casing of the AC mains entrance to your meter is most
likely NOT your house ground. The main AC breaker panel for your home,
whether that be in a garage or wherever (surely close to the meter though)
is where the house AC neutral wiring and house AC ground wiring all meets at
one bonding location. THAT is the source of the single point ground
conductor, which leaves your panel and finds the nearest approved earthing
connection. You may have to get under your house to see where that green
bonding jumper drops down from the panel, and penetrates the outside wall,
then connects via a bronze ground rod clamp to the home's single point
ground rod. Telephone and cable and all radio shield grounds MUST BOND to
this ground rod. It is probably just inches beneath finished grade, and
within a foot or so of your foundation wall, right outside the breaker
panel.

In the unlikely event that your builder actually used the aluminum casing of
buried conduit for his AC mains ground connection, then the telephone
company was proper in bonding to the same place. But if you have a buried
ground rod as 99% of residences do, then that is the ONLY place that all
utilities must ground to.

The reason it would be unlikely to have the conduit as a earthing ground
connection? Because the utility should inspect for a contractor installed
ground rod before they hook up. Using their buried conduit, while possibly
legal, would be unusual at best.

Hope this helps,

Jack