"Equipment Grounding Conductor" or "Bonding Conductor"

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vick67

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I copied this picture from an old closed thread and I have always had some confusion as to the name of the wire between the X0 and first ground bus. Should it be treated as an equipment ground and sized by 250.122 or a bonding ground and sized by 250.66?


Xfmr.png

Thanks for the replies.
Chad
 
the wire between XO and the grounding bar in the transformer is called the system bonding jumper. It is sized the same way as the Main Bonding jumper is, per 250.28(D)(1)
 
vick67 said:
Sorry Gary I meant to say between the ground in the transformer and the ground in the first panel.
Thanks,
Chad
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That is a supply side bonding jumper and is sized per Table 250.66 or the 12.5% rule for where the largest phase conductor exceeds 1100 kcmil.

See 250.30(A)(2) in the 2011 code
 
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Thanks Don. If this panel had feed thru lugs to a second panel then the supply side bonding jumper wire size would remain constant until all panels are bonded is the way I see it.
 
vick67 said:
Thanks Don. If this panel had feed thru lugs to a second panel then the supply side bonding jumper wire size would remain constant until all panels are bonded is the way I see it.
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It stays a supply side bonding jumper until the circuit has overcurrent protection. At that point the conductors become feeders or branch circuits and you install an EGC sized per 250.122.
 
If using parallel raceways the SSBJ is sized according to the phase conductors in each parallel raceway.
 
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