Bonding Pull Boxes?

K

kjroller

Member
Location
Dawson Mn
Occupation
Master electrician
I am using 2/0 conductor 480 three phase for a compressor it is piped with rigid conduit and LFMC with grounds I didn't use fittings to pull because it is such a tight bend radius instead I used metal pull boxes. I normally bond these with the equipment ground I pull in but a co worker of mine is saying you do not have to what are your thoughts do you bond or not bond the pull box if its not a splice box?
 
Are there any concentric or eccentric KO's? The metal pull box requires a bonding jumper if the circuit conductors are spliced within the box and there is an EGC.
 
infinity said:
Are there any concentric or eccentric KO's? The metal pull box requires a bonding jumper if the circuit conductors are spliced within the box and there is an EGC.
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No there is no Concentric or eccentric KO's and no splices so I am assuming he is right since it is bonded through the pipe and there is no splices I normally just bond it for good practice if rust or corrosion ever comes into play and the bond is lost but from what I can tell if it is just a pull box and no splice is made it does not need to be bonded to the box the conduit serves as the acting bond.
 
kjroller said:
No there is no Concentric or eccentric KO's and no splices so I am assuming he is right since it is bonded through the pipe and there is no splices I normally just bond it for good practice if rust or corrosion ever comes into play and the bond is lost but from what I can tell if it is just a pull box and no splice is made it does not need to be bonded to the box the conduit serves as the acting bond.
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Since there are no splices the standard locknuts are sufficient to bond the box.
 
You said LFMC with grounds but not sure what you mean... is LFMC in the pipe run and part of the ground path? LFMC has limitations on grounding. Did you jumper to the rigid pipe around the flex, or is there some other way the rigid conduit has been properly grounded? If so, you are probably good as long as the wires aren't spliced in the pull box.
 
suemarkp said:
You said LFMC with grounds but not sure what you mean... is LFMC in the pipe run and part of the ground path? LFMC has limitations on grounding. Did you jumper to the rigid pipe around the flex, or is there some other way the rigid conduit has been properly grounded? If so, you are probably good as long as the wires aren't spliced in the pull box.
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I think LFMC only has 20 amp limit for a ground path let me know if im wrong but run a ground on the outside of the lfmc to bond between the rigid piping.
 
kjroller said:
Not in front of my code book but looks like good for 60 amps for some sizes
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Yes, so says 250.118. 60A okay for 3/4 through 1-1/4" sizes.

Not sure if/why you couldn't go larger than 1-1/4" as long as the OCPD is still not greater than 60A. Doesn't exactly say you can't. But since with 2/0 480V you must be using a larger size, maybe you do need a wire EGC if you want to be sure of avoiding the argument with the AHJ.

If the LFMC cannot be an EGC then the pull box needs to be bonded with a wire EGC regardless of 250.148.
 
Anything EMT+ is fine if non-concentric KO.
FMC <=20A, <=6ft is fine.
LFMC <=60A if >=3/4", <=6ft is fine.
Otherwise pull a wire.

NEC2020
 
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