CONDUCTORS IN PARALLEL
- Thread starter jjg
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marissa2
Senior Member
- Location
- Connecticut
Re: CONDUCTORS IN PARALLEL
No, you must run one conductor from each phase in each conduit.
No, you must run one conductor from each phase in each conduit.
- Location
- Massachusetts
Re: CONDUCTORS IN PARALLEL
Yes, sometimes, in very limited applications.
300.3(B)(1)
I have done this for some services and it works well at the terminations as long as the number of sets is divisible by four (at least for 3 phase 4 wire installations).
[ July 14, 2003, 05:59 PM: Message edited by: iwire ]
Yes, sometimes, in very limited applications.
300.3(B)(1)
It is important that you follow the requirements of 300.20(B).
I have done this for some services and it works well at the terminations as long as the number of sets is divisible by four (at least for 3 phase 4 wire installations).
[ July 14, 2003, 05:59 PM: Message edited by: iwire ]
websparky
Senior Member
- Location
- Cleveland, Ohio
Re: CONDUCTORS IN PARALLEL
jjg,
iwire is correct and as he says, very limited for isolated installations.
I would be sure to get the AHJ's OK before installing isolated!
Dave
jjg,
iwire is correct and as he says, very limited for isolated installations.
I would be sure to get the AHJ's OK before installing isolated!
Dave
marissa2
Senior Member
- Location
- Connecticut
Re: CONDUCTORS IN PARALLEL
I missed that, but if is allowed only in limited applications why would you want too. I would still be afaird the wires would over heat.
I missed that, but if is allowed only in limited applications why would you want too. I would still be afaird the wires would over heat.
gregoryelectricinc
Senior Member
Re: CONDUCTORS IN PARALLEL
Overheating would only occur if you did something that was NOT allowed by NEC. (such as installing metal locknuts, terminating to a metal enclosure, etc. etc.) I have used this option to my advantage on a couple of occasions and yes, it is better, if your parralell runs are divisible by 4.The space it saves you in the bottom of an MDP is worth it.
Overheating would only occur if you did something that was NOT allowed by NEC. (such as installing metal locknuts, terminating to a metal enclosure, etc. etc.) I have used this option to my advantage on a couple of occasions and yes, it is better, if your parralell runs are divisible by 4.The space it saves you in the bottom of an MDP is worth it.
- Location
- Massachusetts
Re: CONDUCTORS IN PARALLEL
Two times I have done this where identical 3000 amp switch gear that is bottom fed.
The lugs are close to the floor so room is tight to cross and keep the same length thirty two 500 kcmils.
If you do isolated phase you can bring the PVCs right in under the lugs with no crossing of conductors, at the transformer end there is plenty of space to cross.
Bob
[ July 14, 2003, 07:08 PM: Message edited by: iwire ]
The only application I have found this good for is for the service conductors from a padmount transformer and the switch gear inside.
Two times I have done this where identical 3000 amp switch gear that is bottom fed.
The lugs are close to the floor so room is tight to cross and keep the same length thirty two 500 kcmils.
If you do isolated phase you can bring the PVCs right in under the lugs with no crossing of conductors, at the transformer end there is plenty of space to cross.
Bob
[ July 14, 2003, 07:08 PM: Message edited by: iwire ]
Re: CONDUCTORS IN PARALLEL
marrisa jut to add a little more and this is out of a text book, when the conductors are run in parrallel and the phases are isolated in a nonmetallic raceway per 300.5 (I). there is no inductive heating within these raceways. However the raceways shall not enter a metallic enclosure individually. this causes inductive heating of the metal where the individual phase conductors penetrate the enclosure
marrisa jut to add a little more and this is out of a text book, when the conductors are run in parrallel and the phases are isolated in a nonmetallic raceway per 300.5 (I). there is no inductive heating within these raceways. However the raceways shall not enter a metallic enclosure individually. this causes inductive heating of the metal where the individual phase conductors penetrate the enclosure
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