Wiring considerations

[Mark Olenick]

Hello all,

So I have a mixed use building. Ground floor Mercantile, 2nd story Residential. When considering wiring I'm really thinking just running 12/2 (or better as required) and skipping 14/2 all together (except for interconnect smoke/fire detectors).

Other than increase cost for extra copper, appreciate thoughts an this course of action

Thanks

 

[Cacher_Chick]

Commercial buildings are wired with 20A receptacles, which would require a minimum 12ga wire. In a large building with a lot of cable runs (or really long runs), it is sometimes necessary to derate the wiring, making 10 ga use even more common.

 

[Sponsor]

 

[Mark Olenick]

Thanks and understood. What about for lighting circuits? I know it depends on loading and such but what if it will all be LED or CFL? Is it just easier to run a single 12 gauge and put all the ceiling lighting on single circuit? or maybe two if I don't need the switching diversity.

 

[Jadnashua]

12g costs more, is stiffer, and a bit harder to work with, but as long as you're not overloading the circuit, run what you prefer as long as it meets the requirements of the device it is powering, meets current codes for your building, and the cb feeding it. A simple light switch may not last as long if used near it's capacity. SOme designs have less arcing internally than others and the heat and potential arching when turning off might be a long-term issue.

 

[Speedy Petey]

Commercial buildings are typically wired with 20A receptacles, which would require a minimum 12ga wire.

Fixed your comment. It's NOT mandatory or required, it's just typical.

In a large building with a lot of cable runs (or really long runs), it is sometimes necessary to derate the wiring, making 10 ga use even more common.

It's not at all common to see #10 used on 20A circuits. It is done occasionally for reasons stated, but it's not common.

 

[Speedy Petey]

Thanks and understood. What about for lighting circuits? I know it depends on loading and such but what if it will all be LED or CFL? Is it just easier to run a single 12 gauge and put all the ceiling lighting on single circuit? or maybe two if I don't need the switching diversity.

ALL the ceiling lights??? I have seen retail stores with hundred of lights. We have NO idea what type of "mercantile" this is, or how big it is. There is NO way for us to know if you need one, two or ten lighting circuits.

This is a commercial setting. Wouldn't your licensed qualified electrician know all this?

 

[WorthFlorida]

Bottom line for commercial property is every is OK until there is a fire, or some is electrocuted or injured. When the insurance claim is filed, the first thing on the insurance inspection is they are going to want to see the inspection sign off from the local authority that issued the permit. No permit, no sign off, maybe no insurance coverage. Get a licensed electrician if you have to ask these type of questions.

 

[Bruce09]

There's plenty of things folks can diy around the house, but after being a member less than 24 hours of this forum, clearly going into something as serious as me considering playing a professional electrician for the weekend, was just plain ignorant and definitely not worth risking mine or anyone else's life just to save a few bucks. You guys probably won't ever know how many accidents yall have prevented by putting this informative information out there..

 

[Mark Olenick]

ALL the ceiling lights??? I have seen retail stores with hundred of lights. We have NO idea what type of "mercantile" this is, or how big it is. There is NO way for us to know if you need one, two or ten lighting circuits.

This is a commercial setting. Wouldn't your licensed qualified electrician know all this?

Apologies for not providing more detail. Front end is 2400 SF minus counter space etc. Probably less than 4 dozen 90 watt equivalent dimmable LED flood lights. Altogether less than 1000W total (actual ) draw. Since all will be when the store I open figured might just be easier for one circuit.
Thanks

 

[Mark Olenick]

Yes - all work done by licensed electrician.