Grounding and Bonding Two Services

[dbaltazar]

A new 4000A service is to be added within an existing electrical room that already contains a 4000A service. The new 4000A service is to power a new expansion to the existing building. What it the proper way to ground and bond the new building expansion in this situation per the NEC? Can someone point toward the section in code that would dictate such a situation?

 

[augie47]

Look at 250.64(D)

 

[Canton]

A new 4000A service is to be added within an existing electrical room that already contains a 4000A service. The new 4000A service is to power a new expansion to the existing building. What it the proper way to ground and bond the new building expansion in this situation per the NEC? Can someone point toward the section in code that would dictate such a situation?

Need a little more information…ground and bond is a little vague

 

[Dennis Alwon]

I believe you treat it the same way you would any service. I assume the other service is already connected to a grounding electrode system.

 

[infinity]

I assume the other service is already connected to a grounding electrode system.

I would think so. I would look into tapping off of the existing 4000 amp service GES.

 

[dbaltazar]

I appreciate all of your responses. For clarification, the new 4000A switchboard would then need to be bonded to the existing main ground bus/grounding electrode system via a grounding electrode conductor and this GEC would be sized per table 250.66, correct?

 

[tom baker]

Close, Section 250.66. Otherwise you would make the copper development association happy by having run a 3/0 Cu to a ground rod

 

[infinity]

I appreciate all of your responses. For clarification, the new 4000A switchboard would then need to be bonded to the existing main ground bus/grounding electrode system via a grounding electrode conductor and this GEC would be sized per table 250.66, correct?

Yes, #3/0 is the largest GEC ever required so for a 4000 amp service that would be the correct size.