Raceway Bond to EGC

[rhy_fraser]

Need a little clarification for bonding jumper.... Our contractor ran a 4/0 bare ground from equipment to a plate which ties into the grounding grid. Since this was done in EMT they installed a #6 bonding jumper from the conduit to the plate as well. Our client has concern that this jumper will not provide sufficient protection if someone were around the conduit and a fault would occur. I can't find anywhere in the code concerning a bonding jumper for the raceway when bonding an EGC specifically, only thing I found deals with bonding conductors and equipment... I feel that #6 would be fine, but just want to be sure that workers are protected. Thoughts?

 

[infinity]

Are those #4/0 conductors GEC's? If so the#6 also needs to be #4/0. Also GEC's play a very little roll in fault clearing.

 

[roger]

I agree with Rob, those appear to be GEC's and bonding to both ends are not actually for personnel safety. With that said they should have used a fitting similar to below and they wouldn't need the bonding jumper. They are made in other materials than brass.

 

[infinity]

As Roger suggested grounding hub on the end of the raceway is the easiest method as it avoids the need for #4/0 going through a bonding bushing.

 

[rhy_fraser]

My understanding of GECs is they have to go directly to earth/ground per 250.53 and even if a supplemental plate were used the bonding jumper wouldn't have to be larger than a #6 per 250.33 (E). The current set up simply looks like an equipment ground to the plate/grounding grid, not a GEC, but an EGC.

 

[rhy_fraser]

The plate is located on a mezzanine specifically for equipment that runs to the grid.

 

[infinity]

The current set up simply looks like an equipment ground to the plate/grounding grid, not a GEC, but an EGC.

So what is the actual purpose of this? Aren't there EGC's run with the branch circuit circuit or feeders to the equipment?

 

[ramsy]

Since this was done in EMT

PVC conduit avoids bonding issues

 

[infinity]

PVC conduit avoids bonding issues

True, but it's a little late for that.

 

[ramsy]

bonding jumper wouldn't have to be larger than a #6 per 250.33 (E).

If your conductors are 4/0 EGC’s T.250.66 requires #2cu, or 1/0al, so #6 jumpers are still wrong

 

[ramsy]

True, but it's a little late for that.

Fire the schmuck who specified metallic conduit, and replace with laborers with jackhammers.

 

[roger]

My understanding of GECs is they have to go directly to earth/ground per 250.53 and even if a supplemental plate were used the bonding jumper wouldn't have to be larger than a #6 per 250.33 (E). The current set up simply looks like an equipment ground to the plate/grounding grid, not a GEC, but an EGC.

A GEC is earthed but not necessarily jumpers so tell us where the conductors land on the other end. If they are intended to be EGC's you have a problem with 300.3(B)

 

[rhy_fraser]

So what is the actual purpose of this? Aren't there EGC's run with the branch circuit circuit or feeders to the equipment?

They are, I believe this is just an additional equipment ground since they are located on a mezzanine..

 

[roger]

Sounds like someone is making an effort to meet 250.54 and if that is in fact the case it's not much of a concern except for added expense to the project.

 

[rhy_fraser]

A GEC is earthed but not necessarily jumpers so tell us where the conductors land on the other end. If they are intended to be EGC's you have a problem with 300.3(B)

I'm uncertain if they land directly on the equipment or the equipment ground bus

 

[rhy_fraser]

If your conductors are 4/0 EGC’s T.250.66 requires #2cu, or 1/0al, so #6 jumpers are still wrong

T 250.66 specifically governs GECs, not EGCs..

 

[roger]

I'm uncertain if they land directly on the equipment or the equipment ground bus

Well regardless, since there is an EGC run with the circuit conductors these are mostly a waste of materials and labor

 

[infinity]

Well regardless, since there is an EGC run with the circuit conductors these are mostly a waste of materials and labor

Since the EGC is run with the circuit conductors and these are just additional bonding jumpers that are not required by any code then I don't see a requirements to run them in any certain way.

 

[ramsy]

T 250.66 specifically governs GECs, not EGCs..

Forum edit time expired B4 done, see edit below:

T.250.66 is identical to T.250.102, which governs EGC bonding-jumper size, per 250.102(D)

 

[don_resqcapt19]

My understanding of GECs is they have to go directly to earth/ground per 250.53 and even if a supplemental plate were used the bonding jumper wouldn't have to be larger than a #6 per 250.33 (E). The current set up simply looks like an equipment ground to the plate/grounding grid, not a GEC, but an EGC.

EGCs have to run with the circuit conductors. They are not permitted to be run by themselves.
These appear to be GEC,s and where run in a ferrous raceway a full size bonding jumper between the GEC and the ferrous raceway is required by 250.64(E).