Sizing bonding jumpers for myer hubs.

[Jerramundi]

We typically just loop the EGC coming out of the raceway through the lug and it's run continuously to either the neutral bus or EGC bus bar.
250.122 is for equipment grounding conductors.

Bend the EGC when it comes out of the raceway so that you know exactly where it will rest in lug, mark just outside the lug on either side with a sharpie, then take your utility knife and remove that ~1" of insulation, land it in the lug, and continue the run to the bus bar.

 

[infinity]

What if it is beyond the capabilities of lugs that can be mounted by the bonding bushing screws? I could see this happening if a 500 kcmil EGC is prescribed.

You somehow find a way to make it work, drill and tap the bushing, change the bolt, etc. Sometimes modifying the bushing is the only way to make it work because it may be impossible to find an off the shelf bushing that has a lug large enough.

 

[Jerramundi]

What if it is beyond the capabilities of lugs that can be mounted by the bonding bushing screws? I could see this happening if a 500 kcmil EGC is prescribed.

Bond it external to the enclosure using pipe clamps? Just a thought. Not sure if that would be acceptable. I don't really run into much 500 kcmil, but have worked with it once or twice.

 

[Dennis Alwon]

Dennis, why would parallel conductors change anything? Wouldn't the EGC in each raceway need to be "full size" anyway?

Yes but I was responding to the fact that Kwired stated the equipment grounding conductor didn't look large enough in the photo. Also the op had more than one conduit but the equipment grounding conductor didn't get sized based on a parallel setup... Just making sure the op didn't think he would need larger bonding.

 

[kwired]

Yes but I was responding to the fact that Kwired stated the equipment grounding conductor didn't look large enough in the photo. Also the op had more than one conduit but the equipment grounding conductor didn't get sized based on a parallel setup... Just making sure the op didn't think he would need larger bonding.

Likely the jumper in the photo needed to be as large as the largest EGC pulled in the raceways.

Suppose is possible those pulled EGC's may be upsized because ungrounded were upsized for voltage drop, in that case the jumper may not need be same size.

My initial mentioning of parallel circuits maybe has little meaning here, because parallel situations need full size EGC (per T250.122 and the OCPD) in each raceway/cable anyway, though I don't think it ever needs to be larger than the ungrounded conductors in a single raceway/cable (didn't double check, someone will chime in if that is wrong ).

 

[Dsg319]

Likely the jumper in the photo needed to be as large as the largest EGC pulled in the raceways.

Suppose is possible those pulled EGC's may be upsized because ungrounded were upsized for voltage drop, in that case the jumper may not need be same size.

I actually was just thinking a scenario similar to this in my head prior to viewing this thread.... just for giggles say I have 20amp circuit and an EGC size of #8awg to be proportioned to the ungrounded conductors. Could my bonding jumpers still be #12awg ?

 

[LarryFine]

I would say yes, because you could splice #12 onto all of the ungrounded conductors at this point.

 

[kwired]

I would say yes, because you could splice #12 onto all of the ungrounded conductors at this point.

I agree.