GECs, EGCs, & Bonding Jumpers

S

Sunny2995

Member
Location
North Carolina
Occupation
Electrical Contractor
Hello all,
Hoping for some clarification and confidence.
We have a 400A meter can, with a 400A SE rated transfer switch. Out of the transfer switch we’re feeding two 200A sub panels. The two sub panels are mounted in a metal structure. The transfer switch and meter can are on a pedestal a couple feet away. (think back to back). Here are what we have figured for this install, wanted to see what everybody’s thoughts were and if it seemed correct. For our GEC we have a #6 bare solid going from meter can to two ground rods (bonding strap provided with meter from can to neutral lug). Meter can to transfer switch with parallel 3/0 for phase conductors and neutral. Neutrals and equipment grounding conductors are bonded in transfer switch (first means of disconnect). From transfer switch we have a 1/0 going (via pvc raceway) to bond the building steel. Also from transfer switch we have two raceways feeding our 200A sub panels with a #3 EGC because of the 400A OCPD on SE transfer switch. Any clarification or thoughts would be appreciated.

T
 
If you have metallic raceways between the meter and T/S you would need to address bonding of those otherwise I believe you are correct.
 
Welcome to the forum.

Sunny2995 said:
For our GEC we have a #6 bare solid going from meter can to two ground rods (bonding strap provided with meter from can to neutral lug).
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The GEC should connect directly to the neutral or via wire, not through enclosure metal like an EGC may.

Sunny2995 said:
From transfer switch we have a 1/0 going (via pvc raceway) to bond the building steel.
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Same comment as above. Remember, you're earthing the utility neutral, not the premises EGC system.
 
LarryFine said:
Welcome to the forum.


The GEC should connect directly to the neutral or via wire, not through enclosure metal like an EGC may.


Same comment as above. Remember, you're earthing the utility neutral, not the premises EGC system.
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I was under the impression a bonding strap from neutral to the can that’s provided with the enclosure by the manufacturer can act as the bonding jumper from GEC to neutral if the manufacturer intended it to be used that way (service rated). Unless I’m misunderstand you
 
Sunny2995 said:
I was under the impression a bonding strap from neutral to the can that’s provided with the enclosure by the manufacturer can act as the bonding jumper from GEC to neutral if the manufacturer intended it to be used that way (service rated). Unless I’m misunderstand you
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And from there the neutrals to disconnect (egc and bonding wires all bond to neutral there). Power company requires GEC bond in meter can.
 
If I am understanding the set up correctly,

GEC(s) to neutral to meter enclosure bonded.

Neutral to transfer switch bonded to case with MBJ, and EGCs come from there to the two 200A OCPDs. Also bonded here is building steel, not to be an electrode, but for 250.104 purposes (likely to become energized).

It kind of sounds okay to me. So long as you got the requirements for supply side bonding jumpers met.

See 250.24 and 250.92. The below photo from, NFPA link enhanced content under NEC 2020 (Also handbook edition) article 250.92(B) kind relates to your set up. Where the gutter is the meter can enclosure and the disconnects would be your single ATS.

1741366115589.png
 
augie47 said:
If you have metallic raceways between the meter and T/S you would need to address bonding of those otherwise I believe you are correct.
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I think Augie mean if you have a nonmetallic raceway. A metal raceway acts as an article 250.102 supply side bonding jumper. If it is nonmetallic all exposed metal parts that may become energized have to bonded with a supply side bonding jumper.
 
Sunny2995 said:
I was under the impression a bonding strap from neutral to the can that’s provided with the enclosure by the manufacturer can act as the bonding jumper from GEC to neutral if the manufacturer intended it to be used that way (service rated). Unless I’m misunderstand you
Click to expand...
I'm referring to the GEC connection through the enclosure metal, not the neutral connection.

That strap may suffice to bond the enclosure to the neutral, but not the GEC to the neutral.
 
I was referencing 250.92 for bonding service raceways. A metallic nipple with service conductors would need to meet 250.92
 
LarryFine said:
What I'm saying is that the GEC in this pic could not merely land on the trough metal.
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The meter can came with a lug preinstalled directly to back plate of meter jaws support/can. The neutral lug has a bonding strap that is attached to the meter jaws support/meter can that says remove when service is not grounded and came factory installed as well. I don’t have a EGC in meter can due to it being installed “upstream” of service disconnect.

augie47 said:
I was referencing 250.92 for bonding service raceways. A metallic nipple with service conductors would need to meet 250.92
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The raceway between ATS and meter can is pvc.
 
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