We have a 3 phase, 4 wire, 480/277 volt system. The service entrance conductors from the transformer to the service entrance disconnect consist of 3 parallel sets of 3 - #500 phase conductors and 1 - #500 neutral conductor in PVC Sch. 40 conduit. Is it legal to put the GEC conductor in with these cables or must it be in its own conduit?
GEC with service cables
- Thread starter mcgil123
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lauraj
Senior Member
- Location
- Portland, Oregon
Re: GEC with service cables
230.7 Exception 1 from the 05 code book, says that you can run grounding conductors in the service raceway, and I suppose a grounding electrode conductor is a grounding conductor according to the definition of grounding conductor in article 100. With this being a parallel installation though, I don't know how running a GEC in just one of the raceways would affect the circuit. Why would you want to do this anyway?
230.7 Exception 1 from the 05 code book, says that you can run grounding conductors in the service raceway, and I suppose a grounding electrode conductor is a grounding conductor according to the definition of grounding conductor in article 100. With this being a parallel installation though, I don't know how running a GEC in just one of the raceways would affect the circuit. Why would you want to do this anyway?
- Location
- Logan, Utah
Re: GEC with service cables
Check out 250.64 specifically 250.64(E)
Chris
Check out 250.64 specifically 250.64(E)
Chris
Re: GEC with service cables
I had similar circumstance, Large 3 phase panel inside and ct can outside on a concrete building that I didn't want to drill a hole in to get the gec from the interior panel to the exterior ground. So I put the gec in the raceway between the interior panel and the ct can and then from the exterior ct can to the grounding electrode. The inspector shut me down. I did some looking in the code and as of yet have not been able to find where it says one way or another(not that it is not there)I believe that the purpose of this rule if it is actually a rule and not an interpitation is that under ground fault conditions they don't want a voltage induced into the service entrance conductors, it would seem that it would be induced onto the service conductors after the breaker had tripped(when the system should be shut down) and have the potential of back feeding through the service, possibly even the transformer and supply lines etc. It would go along with the rule on metal piping containing the gec, in that the metal piping must be bonded to the grounding electrode to stop the possible difference in potential between the conduit and ground if under ground fault conditions there is large current flow through the grounded conductor, thus inducing a voltage into the metal conduit that is not grounded. The service entrance conductors are not grounded so if a voltage is induced into them under fault conditions would it not energize the ungrounded part of the system (service entrance conductors,Trans.,etc.)This is an interesting question, I hope someone smarter than me reads this and can provide a little more in site.
I had similar circumstance, Large 3 phase panel inside and ct can outside on a concrete building that I didn't want to drill a hole in to get the gec from the interior panel to the exterior ground. So I put the gec in the raceway between the interior panel and the ct can and then from the exterior ct can to the grounding electrode. The inspector shut me down. I did some looking in the code and as of yet have not been able to find where it says one way or another(not that it is not there)I believe that the purpose of this rule if it is actually a rule and not an interpitation is that under ground fault conditions they don't want a voltage induced into the service entrance conductors, it would seem that it would be induced onto the service conductors after the breaker had tripped(when the system should be shut down) and have the potential of back feeding through the service, possibly even the transformer and supply lines etc. It would go along with the rule on metal piping containing the gec, in that the metal piping must be bonded to the grounding electrode to stop the possible difference in potential between the conduit and ground if under ground fault conditions there is large current flow through the grounded conductor, thus inducing a voltage into the metal conduit that is not grounded. The service entrance conductors are not grounded so if a voltage is induced into them under fault conditions would it not energize the ungrounded part of the system (service entrance conductors,Trans.,etc.)This is an interesting question, I hope someone smarter than me reads this and can provide a little more in site.
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