Grounding? bonding seperate service disconnects

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LAYMAN JOE

Senior Member
I have a new building with two tenants. (2) 400 amp fused disconnect switches mounted outside 10' apart. One disconnect feeds one tenants panels and the other feeds the second tenants panels. This is all one 2000 sq foot building. There is copper water pipe and building steel available.

How would you ground and bond this system according to the NEC 2005. Specifically the wiring method you would use in bonding the two disconnects to the ground rod(s), cold water pipe, disconnects frame, and building steel ?

Thanks.
 
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LAYMAN JOE

Senior Member
One utility transformer feeds both disconnects through separate conduit underground. Each disconnect is metered and each disconnect feeds separate tenants.

Considering 230.2 (B) (1), it must be two services.
 
iwire

iwire

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LAYMAN JOE said:
testing dangit!

I thought I had been posting. Something went wrong??
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When your a new member here your first few posts must be manually approved by a moderator. That can happen quickly or may take quite few hours if no moderators are on line.

Your posts should now start going up immediately.:smile:
 
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LAYMAN JOE

Senior Member
My boss wanted to drive one ground rod for each disconnect.
Run GEC from ground rod 1 to disconnect 1 and then to building steel.
Run GEC from ground rod 2 to disconnect 2 and then to building steel.

Run (2) GEC from cold water pipe to go to each disconnect.
Bond all GEC at each disconnect including the frame of course.

What do you think about this installation? Do you think the ground rods should be bonded together at the rods instead of through the building steel?
 
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Bea

Senior Member
LAYMAN JOE said:
My boss wanted to drive one ground rod for each disconnect.
Run GEC from ground rod 1 to disconnect 1 and then to building steel.
Run GEC from ground rod 2 to disconnect 2 and then to building steel.
Click to expand...
Refer to NEC 250.58 the ground rods would have to be bonded together.

In your example it sounds like you have a GEC from rod to disco and from BLDG steel to disco

If this is the case you need to bond the two rods together with bonding jumper
 
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LAYMAN JOE

Senior Member
He was arguing that the building steel would be a sufficient bonding jumper. bonding the two rods at the building steel.:confused:
 
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dahualin

Senior Member
Mike's book "understanding the NEC" says about 250.58 common grounding (earthing electrode) that "the most practical method of meeting this requirement is to ground each of the disconnecting means to a common concrete-encased grounding electrode."

I think the building steel is good enough for the bonding also. It is not necessary to bond the two rods.
 
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