Determining GEC to Bldg.Steel

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wmeek

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Location
Texas
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Electrician
I am installing a 400A 120/240 3 Phase service on metal building. We are paralleling #3/0 Phase A-B-C, #1/0 neutral, and per 250.66 would we take CM #3/0 167800 x 2=335,600 and use #2.

Thanks
 

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
I am installing a 400A 120/240 3 Phase service on metal building. We are paralleling #3/0 Phase A-B-C, #1/0 neutral, and per 250.66 would we take CM #3/0 167800 x 2=335,600 and use #2.

Thanks
Yes. #2 would be the appropriate size GEC
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
this is the scenerio
I am bldg a 400A Service using a 320 Metercan, 3"emt riser w/3-500mcm,1-350mcm service conductors. Load side of metercan i am running 2-2" emt conduits with 3-3/0 & 1-2/0 in each conduit to two 200a disconnects. My question is without a gutter ( which you could have a grounding bar)how would you run the grounds to bldg. steel and water pipe from each disconnect. I would have to have a #2 to bldg. steel and a #2 to water pipe from each disconnect along with a #6 to ground rod from each disconnect. I was trying to not have to run separate conductors twice.
 

infinity

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Location
New Jersey
Occupation
Journeyman Electrician
this is the scenerio
I am bldg a 400A Service using a 320 Metercan, 3"emt riser w/3-500mcm,1-350mcm service conductors. Load side of metercan i am running 2-2" emt conduits with 3-3/0 & 1-2/0 in each conduit to two 200a disconnects. My question is without a gutter ( which you could have a grounding bar)how would you run the grounds to bldg. steel and water pipe from each disconnect. I would have to have a #2 to bldg. steel and a #2 to water pipe from each disconnect along with a #6 to ground rod from each disconnect. I was trying to not have to run separate conductors twice.

You could run one properly sized GEC and tap off to hit the two disconnects and other electrodes with split bolts.

250.66%20Taps.JPG
 

wmeek

Senior Member
Location
Texas
Occupation
Electrician
Is a #2 conductor correct for using 500MCM service conductors or is a 1/0 conductor required for bldg. steel, and water pipe.
 
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