Grounding Large Pull Box

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Coachmike

Coachmike

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Location
Morris County, NJ
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Electrical Contractor
Good day all,
We are pulling 3 sets of 3- 500s BRN ORA YEL 277/ 480v with 3/0 grounds through 3-1/2" EMT and a metal 36X36X12 pull box.
Is grounding of the pull box required? Per what Article in the NEC?
Thanks!
Coach Mike
 
Coachmike said:
Good day all,
We are pulling 3 sets of 3- 500s BRN ORA YEL 277/ 480v with 3/0 grounds through 3-1/2" EMT and a metal 36X36X12 pull box.
Is grounding of the pull box required? Per what Article in the NEC?
Thanks!
Coach Mike
Click to expand...

Wouldn't the EMT be adequate bonding?
 
If u had to u can skin the insulation off the egc and use a split bolt connector to solve a peice of 3/0 to lug mounted on the enclosure

Sent from my SM-G950U using Tapatalk
 
Coachmike said:
Good day all,
We are pulling 3 sets of 3- 500s BRN ORA YEL 277/ 480v with 3/0 grounds through 3-1/2" EMT and a metal 36X36X12 pull box.
Is grounding of the pull box required? Per what Article in the NEC?
Thanks!
Coach Mike
Click to expand...

See 250.97 and 250.148

Roger
 
Coachmike said:
Good day all,
We are pulling 3 sets of 3- 500s BRN ORA YEL 277/ 480v with 3/0 grounds through 3-1/2" EMT and a metal 36X36X12 pull box.
Is grounding of the pull box required? Per what Article in the NEC?
Thanks!
Coach Mike
Click to expand...

Since you're pulling straight through the EMT with standard EMT connectors is sufficient to ground the pull box, nothing additional is required.
 
infinity said:
Since you're pulling straight through the EMT with standard EMT connectors is sufficient to ground the pull box, nothing additional is required.
Click to expand...
What article covers that Rob? ;)

Roger
 
Last edited:
Coachmike said:
Good day all,
We are pulling 3 sets of 3- 500s BRN ORA YEL 277/ 480v with 3/0 grounds through 3-1/2" EMT and a metal 36X36X12 pull box.
Is grounding of the pull box required? Per what Article in the NEC?
Thanks!
Coach Mike
Click to expand...

I want to say if you are just pulling through the can without cutting or terminating, you don’t have to ground the can. But you have to identify the 3/0 grounds with green tape since the conductor is bigger than #6
 
Dennis Alwon said:
Roger, doesn't 250.97 allow the emt to be used as a ground assuming no concentric or eccentric ko's are encountered.
Click to expand...
If such KO's will be potentially inhibiting performance, it is fine to use bonding bushings or other fittings to ensure a bond is made, and you wouldn't have to tap into any EGC that is "pulled through".
 
is it in NEC to limit the max ckt "ocpd" amps (total) that can be in conduit? wondering about say some BC's running in same conduit but the total OCPD adds up to say 300A and conduit is the egc. how well does a bonding bushing hold up if say each BC faults to egc but below each OCPD rating.
 
FionaZuppa said:
is it in NEC to limit the max ckt "ocpd" amps (total) that can be in conduit? wondering about say some BC's running in same conduit but the total OCPD adds up to say 300A and conduit is the egc. how well does a bonding bushing hold up if say each BC faults to egc but below each OCPD rating.
Click to expand...

If it's a high resistance fault I don't think it would matter, and a full ground fault is gonna trip one or more of the faulted circuits so the fault current is gonna fall off pretty fast.
 
ActionDave said:
If it's a high resistance fault I don't think it would matter, and a full ground fault is gonna trip one or more of the faulted circuits so the fault current is gonna fall off pretty fast.
Click to expand...

huh? if my 50A load on say 60A ocpd decides to no longer use the N but to fault over to the EGC (not short), everything is still happy, until that is the egc itself cant handle the amps.

so lets say 10 BC's all running at ~10A each and for whatever reason a fault is there (not a short, not all faults are shorts), now you have 100A on the egc "ccc". i just wondering if that dangerous scenario ever comes into NEC verbiage when bonding bushings are used, or just spurred nuts on a painted box, etc.
 
FionaZuppa said:
huh? if my 50A load on say 60A ocpd decides to no longer use the N but to fault over to the EGC (not short), everything is still happy, until that is the egc itself cant handle the amps.

so lets say 10 BC's all running at ~10A each and for whatever reason a fault is there (not a short, not all faults are shorts), now you have 100A on the egc "ccc". i just wondering if that dangerous scenario ever comes into NEC verbiage when bonding bushings are used, or just spurred nuts on a painted box, etc.
Click to expand...
That is a potential scenario already mentioned that develops a "high resistance fault".

If it is the neutral that has developed the fault - you about need GFP/GFCI to detect it if you want to shut it down in that situation.

Had a service call one time where they were doing some painting in what was originally a mobile/manufactured home. They unplugged the dryer and immediately had some problems in various locations around the house - smoked a TV and some other electronics.

That dryer (installed on 4 wire circuit) never had the bonding jumper removed - the feeder neutral to the house had gone bad (who knows how long ago) and the bonding jumper and in the dryer + the EGC was carrying all the feeder neutral current - until they unplugged the dryer.
 
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