Running a ground without pulling out the feeder conductors

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BillMar

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Suppose you have a feeder originating in a sub station that is 480volt 3ph 4wire, a 300ft run but there was never a ground wire pulled into the conduit with it. Which I know is not to code and if it were a new install, a ground would be pulled in as required. Say you absolutely do not have the time and resources at the time to pull the feeders out and pull back in to get a ground wire back to the substation. But there is 2 spare empty conduits that go back to the substation. How would you get a ground back to the substation in order to get it grounded safely without pulling the wires out of the conduit and with minimal downtime? Of course the plan would be to pull the feeder out and back in with a ground when time permits.
 
If you start at article 300.3(B), and follow the exceptions and the "otherwise permitted" statements, I don't think you will find any way to run an EGC outside the same conduit that contains the feeder conductors. I couldn't, anyway.

I see two choices. One is to pull an EGC through the existing conduit, without first pulling out the existing conductors. I don't think that is generally a good plan, but I also don't think it is a code violation in itself. It runs a risk of causing damage to the insulation of the existing conductors, but I am no judge of whether that risk is significant.

The other choice I see is expensive, but so is the "pull out and re-pull" backup plan you are trying to avoid. You can pull an entirely new feeder, including all required wires, into one of the spare conduits. You can then schedule a short outage to swap connections from the existing conductors to the newly pulled conductors. You should be able to either reuse the old conductors for a future project, or to sell them as salvage, in order to recoup some of the costs of this solution. What I do not know, and could not know without seeing the physical installation, is whether you can safely pull wires through the spare conduit, while the existing system is energized.
 
Grounding conductor

Grounding conductor

Thanks for the reply. The problem I have is that I can't get a grounding conductor in the same conduit without pulling the existing out. Also, the conduit is 4" with 4 #500kcmil conductors at 300ft with some bends which would cost way too much to pull in new ones. Could I pull an EGC through the spare (temporarily) and then do the pull out and in when time permits?
 
It may be to code or may have been to code.

What is the function of the circuit?

Is it a feeder or a service?

Was it installed before the 2008 NEC was adopted?

Is it a metal conduit?

Is the neutral bonded to the enclosure at the load end?
 
BillMar said:
Suppose you have a feeder originating in a sub station that is 480volt 3ph 4wire, a 300ft run but there was never a ground wire pulled into the conduit with it. Which I know is not to code and if it were a new install, a ground would be pulled in as required. Say you absolutely do not have the time and resources at the time to pull the feeders out and pull back in to get a ground wire back to the substation. But there is 2 spare empty conduits that go back to the substation. How would you get a ground back to the substation in order to get it grounded safely without pulling the wires out of the conduit and with minimal downtime? Of course the plan would be to pull the feeder out and back in with a ground when time permits.
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I am making a couple assumptions based on your post.

1. It is a feeder, since you said that explicitly.

2. You state it is 4 wire so I assume it is wye configuration, and you pulled all four wires.

3. You can't use the conduit as an EGC for some reason (perhaps it is plastic).

If these are all the case, I think you are out of luck. For minimal downtime I would run 4 wires and an EGC in one of the spare conduits, make the hookup, then pull the wires out of the existing conduit.
 
charlie b said:
If you start at article 300.3(B), and follow the exceptions and the "otherwise permitted" statements, I don't think you will find any way to run an EGC outside the same conduit that contains the feeder conductors. I couldn't, anyway.

I see two choices. One is to pull an EGC through the existing conduit, without first pulling out the existing conductors. I don't think that is generally a good plan, but I also don't think it is a code violation in itself. It runs a risk of causing damage to the insulation of the existing conductors, but I am no judge of whether that risk is significant.

The other choice I see is expensive, but so is the "pull out and re-pull" backup plan you are trying to avoid. You can pull an entirely new feeder, including all required wires, into one of the spare conduits. You can then schedule a short outage to swap connections from the existing conductors to the newly pulled conductors. You should be able to either reuse the old conductors for a future project, or to sell them as salvage, in order to recoup some of the costs of this solution. What I do not know, and could not know without seeing the physical installation, is whether you can safely pull wires through the spare conduit, while the existing system is energized.
Click to expand...
Thanks for the reply. The problem I have is that I can't get a grounding conductor in the same conduit without pulling the existing out. Also, the conduit is 4" with 4 #500kcmil conductors at 300ft with some bends which would cost way too much to pull in new ones. Could I pull an EGC through the spare (temporarily) and then do the pull out and in when time permits?
 
response to answer

response to answer

iwire said:
It may be to code or may have been to code.

What is the function of the circuit?

Is it a feeder or a service?

Was it installed before the 2008 NEC was adopted?

Is it a metal conduit?

Is the neutral bonded to the enclosure at the load end?
Click to expand...


The circuit is a feeder to an amusement ride. The feeder was pulled in back in the 70's in PVC underground conduit from a substation to a manhole. I had to run the feeder from the man hole to the ride which I did pull the appropriate number of conductors for just trying to get the ride up and running because it was to open in the next few day's. I felt we could pull the ground in one of the spare conduits that ran right along side the feeder conduit until we were closed and then do the job to code by pulling the feeder out and back in again with the ground wire.

Thanks
 
masterinbama said:
the one question that has not been asked is what kind of conduit is it.There is a common misconception here that all conduits need an equipment ground.
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The conduit is PVC Schedule 40 burried 4' under ground that originates in a substation and runs to an underground vault 4x4x6.
 
Repurpose the neutral as a EGC, and put a delta/wye transformer at the end and bond up your brand new SDS? You may not even need a big transformer, as I'd guess that many of the loads would be three phase three wire motors or VFDs for same, the transformer is only needed for loads that need a neutral.

Ok its a heavy ugly solution with costs, but how much do you want to not redo the exisiting cabling...?
 
dbuckley said:
Repurpose the neutral as a EGC, and put a delta/wye transformer at the end and bond up your brand new SDS? You may not even need a big transformer, as I'd guess that many of the loads would be three phase three wire motors or VFDs for same, the transformer is only needed for loads that need a neutral.

Ok its a heavy ugly solution with costs, but how much do you want to not redo the exisiting cabling...?
Click to expand...

It's not that I do not want to redo the existing cable, I would like to pull the EGC in the spare conduit that runs parellel to the feeder conduit until I have the time to pull them out and back in again. It seems to me that since this feeder that has been in long before I was at the facility without a grounding conductor, that at least pulling one in a spare conduit temporarily would at least creat a good ground to reduce any shock hazard until i can pull it out and back in again with the ground.
 
BillMar said:
I would like to pull the EGC in the spare conduit that runs parellel to the feeder conduit until I have the time to pull them out and back in again.
Click to expand...

Sure you would, you've said that, and depite the fact it seems such a sensible thing to do, the concensus is that it is not acceptable. So you are stuck with other solutions.

Perhaps I phrased my last line a little harshly, rereading it it could be seen that I was accusing you of being a slacker, which was not my intent. Just offering an alternative, legitimate solution to a difficult problem.
 
dbuckley said:
Sure you would, you've said that, and depite the fact it seems such a sensible thing to do, the concensus is that it is not acceptable. So you are stuck with other solutions.

Perhaps I phrased my last line a little harshly, rereading it it could be seen that I was accusing you of being a slacker, which was not my intent. Just offering an alternative, legitimate solution to a difficult problem.
Click to expand...

No I didn't take it that way at all, I really appreciate your feedback, I think it's awsome that you take time to help me with this problem. I am very greatful for the response. Your are correct, I know what I have to do.
Thanks.
 
BillMar said:
Suppose you have a feeder originating in a sub station that is 480volt 3ph 4wire, a 300ft run but there was never a ground wire pulled into the conduit with it. Which I know is not to code and if it were a new install, a ground would be pulled in as required.
Click to expand...
As Bob and others have said, are you sure you need an EGC? If this was compliant when installed, it should be okay now. Just bond your end of the neutral.
 
I think you should go with Bob?s suggestion, provided that you can prove the requirements (e.g., no common metal parts) are met.

But let me go off topic a moment. If there were a discarded, six inch long, metal pipe just sitting on the ground somewhere, and if 300 feet away there were a metal clothesline pole stuck into the ground, could you run a wire through an underground conduit that just happens to be close by, and connect that wire to the pipe at one end, and to the pole at the other end, without violating any article of the NEC?

I think you could pull a wire through one of your spare conduits, attach it to the frame of the ride at one end, and at the other end connect it to the frame of the enclosure that contains the breaker feeding the ride. Would that make you sleep better at night? If, and this is a big if, the NEC were to require the presence of an EGC for this installation, if for example you couldn?t apply 250.32(B)(2), then this wire I am describing could not be used as the required EGC. But the world may still be better for its presence.
 
What is a safer installation - 3 phase 4 wire with no EGC, or 3 phase 4 wire with an EGC run nearby in a PVC conduit? The impedance of the temporary EGC in a seperate conduit is more than an EGC run in the same conduit as the phase wires, but it is probably still less than the exisitng ground path.

I am not recommending going against a code requirement. I am just pointing out an application of Ohms law.
 
charlie b said:
I think you should go with Bob?s suggestion, provided that you can prove the requirements (e.g., no common metal parts) are met.

But let me go off topic a moment. If there were a discarded, six inch long, metal pipe just sitting on the ground somewhere, and if 300 feet away there were a metal clothesline pole stuck into the ground, could you run a wire through an underground conduit that just happens to be close by, and connect that wire to the pipe at one end, and to the pole at the other end, without violating any article of the NEC?

I think you could pull a wire through one of your spare conduits, attach it to the frame of the ride at one end, and at the other end connect it to the frame of the enclosure that contains the breaker feeding the ride. Would that make you sleep better at night? If, and this is a big if, the NEC were to require the presence of an EGC for this installation, if for example you couldn?t apply 250.32(B)(2), then this wire I am describing could not be used as the required EGC. But the world may still be better for its presence.
Click to expand...

Thanks for the response, I'm not sure I understand your clothsline pole analogy? But I appreciate you time to comment.
 
rcwilson said:
What is a safer installation - 3 phase 4 wire with no EGC, or 3 phase 4 wire with an EGC run nearby in a PVC conduit? The impedance of the temporary EGC in a seperate conduit is more than an EGC run in the same conduit as the phase wires, but it is probably still less than the exisitng ground path.

I am not recommending going against a code requirement. I am just pointing out an application of Ohms law.
Click to expand...

Thanks Bob, you make a good point.
 
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