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tammyrm · Jul 28, 2012, 12:58 PM

My meter base is located about one hundred feet from my house on a wooden stand. It has a disconnect below it and a ground rod driven there. If I run a 4/4/4/2 aluminum wire to the house do I need another ground rod at the house?

stanfortyman · Jul 28, 2012, 01:04 PM

Yes. A ground rod has nothing to do with the service conductors run.

Also, #4AL is not good for a 100A service, which is the minimum size to a dwelling. Did you mean 2-2-2-4?

tammyrm · Jul 28, 2012, 01:08 PM

Originally Posted by stanfortyman

Yes. A ground rod has nothing to do with the the service conductors run.

Also, #4AL is not good for a 100A service, which is the minimum size to a dwelling. Did you mean 2-2-2-4?

It is a 200 amp service it is 4/0 4/0 4/0 2 quad plex wire, having ground rods at both locations will not create a floating ground?

stanfortyman · Jul 28, 2012, 01:13 PM

Originally Posted by tammyrm

....., having ground rods at both locations will not create a floating ground?

What is a "floating ground"?

Either way, not it will not. Ground rods serve a completely different purpose that equipment grounds, and have nothing to do with the functionality of an electrical circuit or service.

mike 165278 · Jul 29, 2012, 02:27 PM

No you do not need to drive another ground rod. Since you have a disconnect on the meter, your main panel is considered a sub-panel. You just need to run a 4 wire (2H, 1N, 1G). What size service do you have?

stanfortyman · Jul 29, 2012, 05:07 PM

He absolutely DOES need another ground rod at the house. This is a detached structure which requires it's own grounding electrode system.

See 250.32

mike 165278 · Jul 29, 2012, 06:12 PM

I interpurt 250.32 differently.

"B) Grounded Systems. For a grounded system at the separate building or structure, the connection to the grounding electrode and grounding or bonding of equipment, structures, or frames required to be grounded or bonded shall comply with either 250.32(B)(1) or (B)(2).

(1) Equipment Grounding Conductor. An equipment grounding conductor as described in 250.118 shall be run with the supply conductors and connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s)."

I read it as the sub panel has to be connected to the ground wire from the original panel, and to the ground rod, not a separate ground rod for the new building. That said, I'm going to agree with stanfortyman and say a ground rod should be provided in addition to the ground you pull with the feed.

stanfortyman · Jul 29, 2012, 07:30 PM

I'm really not sure how you can interpret that any other way, but cool.

250.32(A) is the key:

250.32 Buildings or Structures Supplied by a Feeder(s) or Branch Circuit(s).

(A) Grounding Electrode. Building(s) or structure(s) supplied by feeder(s) or branch circuit(s) shall have a grounding electrode or grounding electrode system installed in accordance with Part III of Article 250. The grounding electrode conductor(s) shall be connected in accordance with 250.32(B) or (C). Where there is no existing grounding electrode, the grounding electrode(s) required in 250.50 shall be installed.

A building or structure served by a feeder SHALL have a GES. If one does not exist you must install one.
This is pretty clear.