Main Bonding Jumper, ECB

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strap89

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I'm trying to understand if a service rated disconnect is grounded properly. The neutral and ground are bonded together at a main bonding jumper plate . What I'm unsure of is the grounding electrode derived from the grounding electrode system. It's being bonded to the breaker enclosure at a separate lug. I assume that the MBJ bonding plate is also bonded to the enclosure as well. It seems to me that the grounding electrode should be bonded at the MBJ bonding plate and not through the enclosure. Thoughts?
 

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strap89 said:
I'm trying to understand if a service rated disconnect is grounded properly. The neutral and ground are bonded together at a main bonding jumper plate . What I'm unsure of is the grounding electrode derived from the grounding electrode system. It's being bonded to the breaker enclosure at a separate lug. I assume that the MBJ bonding plate is also bonded to the enclosure as well. It seems to me that the grounding electrode should be bonded at the MBJ bonding plate and not through the enclosure. Thoughts?
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The enclosure is bonded through that green bonding screw. Pretty sure that GEC should be up in that spare lug in your MBJ bonding plate.
 
jumper said:
The enclosure is bonded through that green bonding screw. Pretty sure that GEC should be up in that spare lug in your MBJ bonding plate.
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Thanks Jumper. This spare lug is also only attached to the enclosure and not the MBJ bonding plate...
 
jumper said:
Wait a minute.

Why does the service disco have an incoming and outgoing green/ground wire?
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Could be for a bonding jumper on a metallic raceway that contains the SEC's but you would need a wider angle photo to make that determination.
 
shortcircuit2 said:
250.24(A)(1) seems to imply that the connection of the GEC should be to the terminal or bus to which the grounded service conductor is connected.
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Agreed, since the MBJ is a screw then it must connect directly to the grounded conductor.
 
You are correct. At the service disconnect, you cannot use the enclosure as a "conductor" for the GEC to the "grounded conductor" neutral bus bond. I've seen it wired the way you show more times than I can count. Always seemed to be a "I never heard that" moment when I made the contractor fix it. We, as a utility were not Code enforcers, but if the inspector missed it, I was the bad guy. You could just install a jumper (correct size) from the ground bus to the neutral bus, since your GEC wire may be too short to reach. I think it's 250.24.A, but I'm not sure. Been retired from a utility long enough that my memory fades.
 
electrofelon said:
I think the GEC would have to land directly on the same bar/bus as the grounded conductor, or it could attach to the grounded conductor directly
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It could land on a separate EGC bus if the main bonding jumper is a wire type or bus bar type.
 
meternerd said:
You are correct. At the service disconnect, you cannot use the enclosure as a "conductor" for the GEC to the "grounded conductor" neutral bus bond. I've seen it wired the way you show more times than I can count. Always seemed to be a "I never heard that" moment when I made the contractor fix it. We, as a utility were not Code enforcers, but if the inspector missed it, I was the bad guy. You could just install a jumper (correct size) from the ground bus to the neutral bus, since your GEC wire may be too short to reach. I think it's 250.24.A, but I'm not sure. Been retired from a utility long enough that my memory fades.
Click to expand...
Thanks!
 
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