Feeder Cable Installation

[joshnelms]

I'd like to install permanent feeder cable extensions in our building, but I'm not sure the best way to do it. We already have cam loc tails from our disconnect panel, but would like to make up some cam loc extensions to have my disconnects available in another room.

I have some 3" conduit running between the two rooms, but wasn't sure if I'd be OK to run the feeder cable through that conduit. It would be about a 70ft. conduit length.

Does anyone have any useful information on this? I wasn't sure if heat would be an issue with this or not. Also, do I need to use SC cable for this or is there more of an install grade cable that would be better to use?

[epimetheus]

I'm gonna go out on a limb here and say this work is easily in the realm of a licensed electrician. Plus, there's most likely issues with using a temporary connection on permanently installed cables.

[mstaylor]

There are a ton of variables that we could never answer without seeing it, plus it may violate the TOS for the site. You need to get a local electrician that can inspect your local conditions and recomend the proper size and type to run.
Yes, it is possible to install extensions but it isn't as simple as that.

[FMEng]

Portable type cables are not intended for use in a conduit. They will overheat because they are designed for use in free air. I would also recommend consulting with a licensed electrician.

[mstaylor]

Originally Posted by FMEng

Portable type cables are not intended for use in a conduit. They will overheat because they are designed for use in free air. I would also recommend consulting with a licensed electrician.

You guys are exactly right and that's what I meant by getting an electrician to spec size and type. I don't think he has the actual wire yet so he needs to he local contractor to give him specs.

[mrb]

you absolutely cannot do that. cords may not be used as a replacement for building wiring. Type SC is a cord, not building wire. The ampacity is wrong for use in conduit. and a whole slew of other reasons I cant think of at the moment.

[ship]

On the other hand, you can perhaps help run/pull the licenced electrician with the cable run in doing the work to save money and learn lots.

One summer, I designed and plotted out the wiring of the second and third floors in new layout for an old catholic grade school attached to a 1926 German opera house. This design and after the install of the studio theaters on both floors I spent helping the electrician move the old service from the stage to the school part and installing the new service to the stage.

Stuff like running the conduit and helping to pull like a 400' run of 400MCM thru conduit from the stage, over the fly space cored thru the procenium, over the house into the second floor of what was once a church's grade school now rental offices and theater spaces. Great learning experience, bought my pair of ratcheting cable cutters during it I still have and constantly use.

Also learned that the Polish electricians the general contractor hired for the job could neither read a blue print, nore knew much about electrical wiring. Their way of shutting off a circuit breaker was to cause a short, that and beyond every outlet for one side of the school was run off the same circuit breakers. Two circuit breakers because there was no neutral used... So much for my calculated balanced loading and distribution, in the end it was all about just getting enough circuits available for photo copiers etc. that the renters would be needing and the panel was a mess by the time it was done. Polish electricians... jokes asside in me being Polish, they were not just a joke but dangerous.

Side note, the General Contractor for the building side of the renovation was different than the person bringing in a new service to the stage and moving the old power to the school's main panel. What the above Polish electricians did with the power after the main panel was the only problem in the install other than at times late at night after the carpenters were done having to move walls also at times. Blue print verses I feel like putting this wall here...

[joshnelms]

Thanks for all the advice. I'll have an electrician come and take a look at it. I appreciate the quick response.

[STEVETERRY]

Originally Posted by joshnelms

Thanks for all the advice. I'll have an electrician come and take a look at it. I appreciate the quick response.

Make sure he sizes the wire considering the neutral as a current-carrying conductor, which is required for non-linear loads like phase-control dimmers.

ST

[derekleffew]

Originally Posted by STEVETERRY

Make sure he sizes the wire considering the neutral as a current-carrying conductor, which is required for non-linear loads like phase-control dimmers.

Try as you might, there still seems to be some confusion on this. Given a permanently installed system, in conduit, should the grounded conductor be sized:
a) the same as
b) 130% greater than
c) 150% greater than
d) 200% greater than
any one of the hot legs (per the NEC)?