Bonding jumper in sub-panel

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Grouch

Grouch

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Hey guys.
I have two questions:
1) When you have a sub-panel, and are bonding the ground bus bar to the sub-panel enclosure, is this bonding jumper considered an equipment bonding jumper? and do you size it based on table 250.122 using the OCPD that feeds the sub-panel?

2) In the 2017 NEC Handbook, exhibit 250.33, they call out one of the bonding jumpers as a 'supply side equipment bonding jumper'. I thought it's considered either a supply-side bonding jumper, or an equipment bonding jumper. To me they are mixing these terms... it's only a SSBJ. can anyone confirm?
 
I see no reason why it would need to be larger than the EGC run with the feeder so IMO it's not a SSBJ.
 
Supply side bonding jumpers do not exist where the equipment is fed by a feeder. They are most commonly found on service equipment and equipment fed from a separately derived system.
 
don_resqcapt19 said:
Supply side bonding jumpers do not exist where the equipment is fed by a feeder. They are most commonly found on service equipment and equipment fed from a separately derived system.
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Agree with the second sentence, but for an SDS aren't the transformer secondary conductors also feeders? They are not service conductors, and they are not branch circuits.

Cheers, Wayne
 
(1) Yes

(2) You'd need to post the exhibit. There's no 2017 NEC section 250.33, so I don't know what you are referring to. If you happen to mean 250.30, that covers grounding SDSs, which is the second case Don mentioned.

But yes, it sounds like the wrong term was used, it should be "supply side bonding jumper" without the extra word equipment.

Cheers, Wayne
 
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Grouch1980 said:
Yes, with the screw, that can also be used as bonding equipment... my question is if you use a wire jumper as an additional means of bonding.
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I agree with #2 it need not be larger than the equipment grounding conductor ran in the feeder feeding the sub panel. This should be based on the size of the overcurrent device protecting the sub panel feeder based on table 250.122. If feeder conductors were increased for voltage drop you need to increase equipment grounding conductor proportionally!
 
Grouch1980 said:
Yes, with the screw, that can also be used as bonding equipment... my question is if you use a wire jumper as an additional means of bonding.
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You don't need to add a wire jumper if the ground bus bar is properly bonded to the enclosure such as by a factory bonding screw.

But say you lost the screw and the ground bus bar is otherwise isolated from the enclosure. Then you could install a wire type bonding jumper, sized as you described in the OP.

Cheers, Wayne
 
wwhitney said:
(2) You'd need to post the exhibit. There's no 2017 NEC section 250.33, so I don't know what you are referring to. If you happen to mean 250.30, that covers grounding SDSs, which is the second case Don mentioned.

But yes, it sounds like the wrong term was used, it should be "supply side bonding jumper" without the extra word equipment.

Cheers, Wayne
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Here's the exhibit, see the attachment. It says 'supply side equipment bonding jumper' in the illustration. 3rd item from the top.

SSBJ.jpg
 
Grouch1980 said:
yes, and? my specific question is regarding the wire labeled 'supply side equipment bonding jumper'. It seems to be mislabeled.
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I think he thought your two questions were about the same thing, but I'm trusting they are not related other than both being about bonding. (Note your subject line is only about the first question.)
 
Grouch1980 said:
Here's the exhibit, see the attachment. It says 'supply side equipment bonding jumper' in the illustration. 3rd item from the top.
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Yes it is a SSBJ because it's protecting the service raceway that has no OCPD ahead of it making it on the supply side of the panel OCPD.
 
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