Equipment Grounding Conductor on the outside of a raceway?

[magictolight.com]

We have to increase the size of a circuit from a 60 amp circuit to an 80 amp circuit and have use of the existing 1" EMT for this new #4 THHN 3 phase and neutral circuit which has been engineered with a #4 equipment grounding conductor. Is it conceivable we could run the equipment grounding conductor on the outside of the 1" emt? The installation is through an office, drop ceiling and sheetrock wall. If we can we could use the exisiting conduit otherwise we have to upgrade to an 1 1/4".

 

[Twoskinsoneman]

We have to increase the size of a circuit from a 60 amp circuit to an 80 amp circuit and have use of the existing 1" EMT for this new #4 THHN 3 phase and neutral circuit which has been engineered with a #4 equipment grounding conductor. Is it conceivable we could run the equipment grounding conductor on the outside of the 1" emt? The installation is through an office, drop ceiling and sheetrock wall. If we can we could use the exisiting conduit otherwise we have to upgrade to an 1 1/4".

Yeah 300.3(B) requires running the EGC in the raceway. Of course the EMT is suitable as the EGC IAW 250.118 so the #4 EGc in unneeded.

 

[Little Bill]

Yeah 300.3(B) requires running the EGC in the raceway. Of course the EMT is suitable as the EGC IAW 250.118 so the #4 EGc in unneeded.

True, but since it was "Engineered" you might want to check with the Engineer to see if he/she would accept the EMT as the EGC.

 

[petersonra]

True, but since it was "Engineered" you might want to check with the Engineer to see if he/she would accept the EMT as the EGC.

who the heck would run a #4 EGC for an 80A circuit in the first place?

 

[Little Bill]

who the heck would run a #4 EGC for an 80A circuit in the first place?

I wasn't saying the #4 would be the correct size, I was only pointing out that if an engineer designed it, they probably would need to be asked the question. Some don't like an electrician or EC to make changes, no matter how dumb it sounds, without consulting them first.

 

[petersonra]

After thinking about it, I am not sure this is a violation.

There is an EGC run with the conductors (the conduit). The wire on the outside of the conduit is a seperate issue. Is there any prohibition on having a green wire run along a conduit?

It is not unusual to have a bonding wire run by itself between large pieces of equipment. How is this any different?

 

[Twoskinsoneman]

After thinking about it, I am not sure this is a violation.

There is an EGC run with the conductors (the conduit). The wire on the outside of the conduit is a seperate issue. Is there any prohibition on having a green wire run along a conduit?

It is not unusual to have a bonding wire run by itself between large pieces of equipment. How is this any different?

bonding jumpers outside the conduit are limited to 6ft

250.102(E)

 

[tom baker]

After thinking about it, I am not sure this is a violation.

There is an EGC run with the conductors (the conduit). The wire on the outside of the conduit is a seperate issue. Is there any prohibition on having a green wire run along a conduit?

It is not unusual to have a bonding wire run by itself between large pieces of equipment. How is this any different?

The NEC limits the bonding jumper to 6ft (with and exception for a pole top bond). 300.3(B) requires all conductors to be grouped together - the further apart the circuit conductors are, the greater the impedance as the magnetic fields don't cancel. The NEC doesn't tell you the why, only the how. For the why, read the IEEE green book.

 

[iMuse97]

bonding jumpers outside the conduit are limited to 6ft

250.102(E)

I've been connecting hundreds of feet of bonding today, all 4/0 and all outside the 4" RMC.

 

[Twoskinsoneman]

I've been connecting hundreds of feet of bonding today, all 4/0 and all outside the 4" RMC.

ok.

 

[petersonra]

The NEC limits the bonding jumper to 6ft (with and exception for a pole top bond). 300.3(B) requires all conductors to be grouped together - the further apart the circuit conductors are, the greater the impedance as the magnetic fields don't cancel. The NEC doesn't tell you the why, only the how. For the why, read the IEEE green book.

The point being that with EMT the EGC is run with the power conductors already.

Is there any prohibition in the code from running a bonding wire that is not associated with power conductors? If there is, a lot of plants are in violation.

Is there any code requirement for seperation of a bonding wire that is run seperately from power conductors?

 

[tom baker]

I've been connecting hundreds of feet of bonding today, all 4/0 and all outside the 4" RMC.

But if thats the EGC, then its a code violation and not likely to do its job. However, many EEs will spec a concrete duct bank with 4/0 or similar in the corners for some reason, maybe lightning.
Thats OK as long as the RMC is used as the EGC.

 

[iMuse97]

But if thats the EGC, then its a code violation and not likely to do its job. However, many EEs will spec a concrete duct bank with 4/0 or similar in the corners for some reason, maybe lightning.
Thats OK as long as the RMC is used as the EGC.

Thanks for your comment. I was mainly responding to the idea that bonding jumpers might be limited in length. As for the rest of the installation I mentioned, there will also be a EGC pulled with the feeders.