Sizing Bonding Jumpers That Are Not Required

[infinity]

If you have a raceway say EMT with an EGC that is terminated to a ground bus, if a bonding jumper is not required but installed anyway is it required to be sized properly? The EGC in this case is 350 kcmil but the largest terminal on a bonding bushing is only 250 kcmil so a 250 bonding jumper was installed.

 

[Dsg319]

If you have a raceway.say EMT with an EGC that is terminated.to a ground bus, if a bonding jumper is not required but installed anyway is it required to be sized properly? The EGC in this case is 350 kcmil but the largest terminal on a bonding bushing is only 250 kcmil so a 250 bonding jumper was installed.

That’s a really good question, if it wasn’t needed to be code complaint or wasn’t even in a company spec and was just installed for giggles/redundant like a “supplemental” ground rod at a light pole that can be any size or depth.

Looking forward to what others have to say… Me personally I would say no if it was not required and could see and make sense of in theory that the raceway is already connected/bonded to the panel.

 

[infinity]

IMO it needs to be the proper size just like if you install an EGC in a raceway that already qualifies as an EGC like EMT. Others are arguing the "I don't really need it" so the size doesn't matter.

 

[Dsg319]

IMO it needs to be the proper size just like if you install an EGC in a raceway that already qualifies as an EGC like EMT. Others are arguing the "I don't really need it" so the size doesn't matter.

That’s a good point, I regularly install a properly sized EGC in a raceway that qualifies.
Both because of job specs and habit/OCD.

 

[Tulsa Electrician]

I have a what if.
Let say you loop the bonding jumper through lug and terminate each end on the ground bus. Know you have a parallel conductor. Then a small conductor can be used for the bonding jumper as long as it's 1/0 other larger. Just thinking outside the box.

To your original question. Once you install it as a bonding jumper than the rule applies.
250.102, does D apply to your install? Load side of OCD.
Was the 350 for VD?

 

[LarryFine]

Then a small conductor can be used for the bonding jumper as long as it's 1/0 other larger.

The minimum size for paralleled conductors does not apply to EGCs.

Once you install it as a bonding jumper than the rule applies.

Agreed.

 

[augie47]

Seems like in the past we discussed installing and undersized EGC in a metal raceway that met 250.118 (so the wire type EGC was not required) and the conccensus of opinion was that doi8nbg so would be a violation. I would think the same applied here. IF you are going to install one, required or not, it should be sized per NEC>

 

[Tulsa Electrician]

What about a bonding jumper for equipment?
310.10 (H) (5)
I do believe what he was describing was an equipment bonding jumper.
If I read correctly the only way to go smaller than 1/0 in parallel was to have a listed cable

Please point me in the right direction. Time for me to read more.

From 2107 NEC:
"5) Equipment Grounding Conductors. Where parallel equipment
grounding conductors are used, they shall be sized in
accordance with 250.122. Sectioned equipment grounding
conductors smaller than 1/0 AWG shall be permitted in multiconductor
cables, if the combined circular mil area of the
sectioned equipment grounding conductors in each cable
complies with 250.122."

 

[Tulsa Electrician]

FYI where i am located were on the 2014 NEC. just had 2017 on pdf
Thanks in advance.
I have been teaching others that 1/0 applies here. I will need to correct

 

[infinity]

Seems like in the past we discussed installing and undersized EGC in a metal raceway that met 250.118 (so the wire type EGC was not required) and the conccensus of opinion was that doi8nbg so would be a violation. I would think the same applied here. IF you are going to install one, required or not, it should be sized per NEC>

My thought as well. From an inspection point of view the bonding jumper could be there for a reason that is not visible like the raceway transitions to another type of raceway somewhere in the run where that second raceway type does not qualify as an EGC. So on both ends it could appear that the jumper isn't required but in reality it may be required and then the proper size is necessary.