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RE: Should I re-ground?

Posted by jea48 (A) on September 26, 2008 at 22:04:19

In Reply to: Should I re-ground? posted by RickeyM on September 26, 2008 at 09:46:50:

If your service is a 100 amp there should be at least a #6awg copper wire that runs from the electrical panel to the main metallic domestic water line where it enters your house ahead of the water meter continuous and unbroken, per NEC. The main water line is the primary grounding electrode. (Note a jumper shall jumper around the water meter)
For a 200 amp service a #4 awg copper wire ran from the electrical panel to the water line.
Most older homes built around middle 1970s and earlier, this may be the only grounding electrode. That was all that was needed to meet the minimum requirements for NEC.

Later NEC code required an addition grounding electrode was needed. A single ground rod driven outside the home with a #6awg, for a 100 amp service, (#4awg for a 200 amp service) copper wire continuous unbroken ran from the electrical panel to the ground rod.

Roughly around the 1999 code edition NEC changed from a single ground rod to a minimum of two ground rods. Still only one copper wire runs from the electrical panel but the wire runs to one ground rod and then unbroken to the next rod. Even though there are two ground rods they are counted as one grounding electrode.

The minimum number of grounding electrodes that are needed to meet NEC 2005 code are two. You can install as many as you want, BUT, all grounding electrodes shall connect together back at the main disconnecting means of an electrical service, in most cases the main electrical panel. All grounding electrode conductors connect to the service entrance neutral conductor.
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An added note:
Local codes vary. But with that said NEC is usually always the bare minimum that shall be met.....

but I wonder if there would be any benefit to adding a grounding rod at the back of the house where the breaker panel is?



It will provide you added lightning protection. Will it change the sound for better of worse of your audio system? I doubt it.

You can add a supplemental grounding electrode per NEC providing your electrician installs a minimum of two ground rods a minimum of 6' apart and a minimum ground wire sized per NEC connects to the same grounding point as the other grounding electrode conductor that connects the service entrance neutral to earth.

In some areas of the country the power utility company may dictate the size, Dia and length of the ground rods. They also may dictate how far from the house foundation the rods are to be driven as well as the distance between the rods.

Example for my area the power company requires a minimum size ground rod of 5/8 X 8' The rods must be a minimum of copper clad, plated, steel rods.

The two rods must be driven into the earth a minimum of 2' out from the foundation wall with a minimum of 8' distance between the driven rods.
The top of the rods must be driven 4" to 6" below grade of the earth. Approved ground rod clamps with a solid bare copper wire, #6awg for a 100 amp service and a solid bare #4awg copper wire for a 200 amp service.

Bottom line your electrician will know what is required for your area.

• Charles Hansen comments on the equipment ground...   (Open in New Window)

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