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grounding back to back install

Posted by jasmar (My Page) on
Sat, Dec 14, 13 at 11:42

What is the norm for grounding/innersystem bonding on a back to back type install (meter base on exterior brick wall/main panel directly behind it in interior garage wall)? Home is 30 years old and panel currently grounded to copper cold water pipe via #6 bare copper wire ran through the attic and down wall cavity in the laundry. I believe this was up to code when home built. Previous home was pier and beam with main panel in the middle of the interior of home. #6 ran down under home to two ground rods on opposite side of where service came into home. Current home is slab. Do I bore a hole through the brick behind the main panel (under the meter can) and pull the ground through and down the exterior wall (possibly installing one of those new intersystem bridges (so phone/tv can be bonded at same point) or do I run ground inside wall cavity and bring it out through the bottom brick right at foundation level? The ground wire should not be coming through the meter can right?

Follow-Up Postings:

RE: grounding back to back install

There are two issues. The first is you need to contact you power company as to what their requirements at the meter pan is. Some have specific ideas where your grounding system is to be located. At your service disconnect you must run ground to your buidlings grounding electrode system. If the service disconnect is inside and the grounding electrode is outside, it's put to you how you get it out there (and your local inspector).

Certain water pipes are indeed even to this day legitimate grounding electrodes. So are two ground rods.

You can connect your other system's grounding in there (but the run from the panel to the ground electrode MUST be continuous (one wire or approved "welded" connections)).
Ideally if the phone/cable enters the house at another point, they should ave their own ground rod and the two system grounds bonded together.

RE: grounding back to back install

I plan to check with the local inspector. Guess my question was more about bonding the meter base and main panel together. Never seen the ground pulled out of the meter box at any of the homes I have lived in but it must be common place somewhere in the country as I see products like this:

RE: grounding back to back install

duplicate posting

This post was edited by jasmar on Sat, Dec 14, 13 at 15:13

RE: grounding back to back install

Again, there's nothing (as far as the NEC goes) that prevents the ground even from the main panel running back through the meter panel through the meter box on it's way to the ground. If the POCO and the local inspector are OK with it, that's fine. Otherwise, you'll have to make some other hole in the house (if the grounding electrode connection is outside). One house I have has a hole bored into the basement rim joist (concrete foundation) for it. My other house has the disconnect on the outside of the house, so it's already out there.

All that "intersystem" grounding thing is a clever little thing that wraps around the grounding conductor to provide the bonding to the other systems. As long as you can slip it over the grounding conductor it will work (it cares not if it's actually connected to the meter pan itself). Since most times, the grounding conductor is already in place (and would be difficult to thread through such devices), people use other clamping terminals over the wire.

As stated the grounding electrode to service disconnect connection must be continuous.

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