ground question

[duluthelectrical]

Is it legal to run your grounding conductor in a seperate pipe than the ungrounded conductors?

 

[crossman]

Assuming you are talking about branch circuits or feeders and equipment grounding conductors:

2008 NEC

300.3(B) is the general section that says "they must be in the same raceway with the circuit conductors."

300.3(B)(2) allows it for existing installations as per 250.130(C). This may be used when replacing existing 2-wire receptacles with 3 wire receptacles. Also, Equipment Bonding Jumpers may be on the outside of a raceway.

As for circuits in one counduit, EGC in another, the answer is pretty much "no".

 

[Pierre C Belarge]

Assuming you are talking about branch circuits or feeders and equipment grounding conductors:

2008 NEC

300.3(B) is the general section that says "they must be in the same raceway with the circuit conductors."

300.3(B)(2) allows it for existing installations as per 250.130(C). This may be used when replacing existing 2-wire receptacles with 3 wire receptacles. Also, Equipment Bonding Jumpers may be on the outside of a raceway.

As for circuits in one counduit, EGC in another, the answer is pretty much "no".

I embelished on the important aspect of the answer provided.

 

[duluthelectrical]

Thanks for the info, I asked because I was sent to a job to try and pull out a number 1/0 ground and put in a 3/0. There is 600's in the 390' rigid run, so keeping the 600's unscathed is important. No way of doing it really, havn't tried big fishin tape but that is pretty much a shot in the dark, so running a seperate pipe for a ground is the easiest way, but legal?

 

[duluthelectrical]

These would be the load side 600 feeder conductors feeding an inverter.

 

[duluthelectrical]

Its almost a no brainer but I think my boss is going to tell me to do it, but I know its not code. I will show him the codes and see what he says then.

 

[crossman]

There is 600's in the 390' rigid run

Is this rigid metal conduit or rigid non-metallic conduit (PVC)?

 

[crossman]

Okay, let us assume it is rigid metal conduit.

Now, 250-118 says RMC is approved as an EGC. So, we actually don't even need an EGC wire in the pipe. So.... if we, just for fun, wanted to run a conduit from the inverter to the other piece of equipment, and we wanted to pull a single 3/0 in it, and tie it to the Equipment Ground at each piece of equipment, would there be an issue then?

As far as I know, there is nothing preventing us from bonding equipment together just for the "fun" of it. We can put bonding jumpers wherever. And we can protect them from physical damage by placing them in conduit?

So, maybe that is the way to get around this.

 

[quogueelectric]

Okay, let us assume it is rigid metal conduit.

Now, 250-118 says RMC is approved as an EGC. So, we actually don't even need an EGC wire in the pipe. So.... if we, just for fun, wanted to run a conduit from the inverter to the other piece of equipment, and we wanted to pull a single 3/0 in it, and tie it to the Equipment Ground at each piece of equipment, would there be an issue then?

As far as I know, there is nothing preventing us from bonding equipment together just for the "fun" of it. We can put bonding jumpers wherever. And we can protect them from physical damage by placing them in conduit?

So, maybe that is the way to get around this.

The problem with running a single ground in a metalic pipe is when a fault tries to carry down the conductor the pipe acts as a choke and builds magnetic resistance as the amperage increases sudenly.

 

[roger]

The problem with running a single ground in a metalic pipe is when a fault tries to carry down the conductor the pipe acts as a choke and builds magnetic resistance as the amperage increases sudenly.

Just bond the conductor to the pipe at both ends and there is no choke effect.

In Crossman's scenario the pipe enclosing the EGC wire conductor would be physically connected to the equipment and the conductor is too, the bonding is already done.

Roger

 

[Pierre C Belarge]

250.102 Equipment Bonding Jumpers.

(E) Installation.​

​

​

The equipment bonding jumper shall be
permitted to be installed inside or outside of a raceway or
enclosure. Where installed on the outside, the length of the
equipment bonding jumper shall not exceed 1.8 m (6 ft)
and shall be routed with the raceway or enclosure. Where
installed inside of a raceway, the equipment bonding
jumper shall comply with the requirements of 250.119 and
250.148.​

Exception: An equipment bonding jumper longer than 1.8
m (6 ft) shall be permitted at outside pole locations for the
purpose of bonding or grounding isolated sections of metal
raceways or elbows installed in exposed risers of metal​

conduit or other metal raceway.

 

[crossman]

So back to my scenario.

Rigid metallic conduit is the equipment ground for the feeder.

Is there anything preventing me from running another conduit from equipment to equipment and putting a single conductor in it and connecting this single conductor to the equipment enclosures on each end?

Technically, this conductor is a bonding jumper and is not even associated with the feeder. If I want to make sure there is a good bonding connection between equipment, what would prevent me from doing that?

The Code is a minimum. If I want to run copper bonding jumpers all over the place in my building, connecting all my equipment together, I don't think the Code stops me.

In Article 100, there is a definition of Bonding Jumper, Equipment, and there is a definition of just Bonding Jumper. Section 250.102 applies to Equipment Bonding Jumpers, not to Bonding Jumpers.

 

[don_resqcapt19]

The Code is a minimum. If I want to run copper bonding jumpers all over the place in my building, connecting all my equipment together, I don't think the Code stops me.

It would not be a code issue, but would they serve any real purpose?

 

[crossman]

They may not serve any purpose.

But I was referring to the OP. If the existing feeder is in RMC and the boss wants to run a second conduit and install a 3/0 conductor in it and attach it to the equipment, I don't see that there is a code violation.

We originally told the OP that it was against code to do what was being suggested. But on further thought, it actually is not against code (if we are using RMC for the original feed).

 

[duluthelectrical]

Thank you for your answers, the conduit run is 4" rigid. Heres the run in detail,2 -4" rigid conduits running from the 800 amp disco, through 2-4" mogul style lbs. To a 36x 36 pull can then run 300ft to another pull box then to mogul style lbs again, keep in mind rigid all the way down the wall until it 90s into dirt , it then turns to pvc into the switchgear feeding the inverter. We use myers hubs on all of out connections to the pull boxes.

 

[don_resqcapt19]

But I was referring to the OP. If the existing feeder is in RMC and the boss wants to run a second conduit and install a 3/0 conductor in it and attach it to the equipment, I don't see that there is a code violation.

It is still a violation if the boss calls it an EGC:grin:

 

[crossman]

It is still a violation if the boss calls it an EGC:grin:

Yep!

The boss just best call it a bonding jumper!:wink:

 

[crossman]

Okay, based on the latest info, there is PVC involved. So, my scenario will not work. Looks like the 3/0 needs to be pulled into the conduit.

 

[haskindm]

If I understand that this is a parallel installation, it will need a full-sized egc in each conduit.

 

[duluthelectrical]

Ok so the pipe run is rigid metal all the way from the disconnect all the way to the switchgear until in goes underground up into the gear, which is pvc. Just telling that to make clarity of this. The parallel pipes are 400' long and having 600s in them makes pulling out the existing 1/0 ground extra hard. Pulling out the 600s is extra hard, trying to reuse them is extra hard since it is sim pull brown orange yellow wire and the insulation isn't as durable as regular thhn. Oh what fun. Never trust the prints or engineers, as they didn't do the proper homework, 250.122 says 3/0 ground.