What type of wire for small subpanel feeder?

jshattoc

I'm installing a small 30A subpanel in my basement to supply 4 15A 110VAC circuits. No special load on any of them, can lights and general purpose receptacles. For the run from the main service panel, to the sub, can I use NM cable? Or does it need to be a "heavier" grade, like AC or MC, or perhaps THHN inside EMT? The feeder will be through studs/along joists, behind drywall, in a single-family residential setting. Not sure of the exact length, but it will be less than 25 feet in the absolute worst case.

Also, am I correct in reasoning that this panel will not need a local disconnect, due to the low ampacity and number of circuits?

teamo

You can use 10/3 NM. At the sub panel the neutral and ground bus bars are not bonded. With only 4 circuits you do not need a disconnect. At the main panel use a two pole 30 amp breaker.

nap

depends on where you are. In most of the US, NM of the proper size would be fine. In the Chicago area, conduit is a must. Other areas vary.

the panel doesn't need a local disconnect simply by the fact it is in the same building as the feeder panel.

LyonsElecSupply

While you dont need a disconnect locally by code, it is a very good idea if you have the budget to put one in to do so.

It makes it safer to work on as you have DIRECT control over the disconnecting means when performing service inside the panel. The only time I would not is if the subpanel is adjacent to the main (expansion panel)

You usually upsize panels for possible expansion, might as well throw a MB/Disconnect in it.......

Thats my 2 safety cents.

__________________
"Do it right the first time and avoid duplication of effort"

Your AHJ/Inspectors ALWAYS have the final say on ANY electrical code issue.
If in doubt, contact a licensed, experienced, reputable electrician to perform the work.

jlmran

Isn't that served by the breakers in the main panel?

AndyinAtl

By direct control he means having the disconnect within sight.
I personnaly would not install a main breaker unless it was specifically requested or there was tons of money in it for it.

In a resi situation threatening the lives of the people in the residence if they touch the panel while I am working in the other panel has always been sufficent.

In a commercial setting I use lock out tag out.

LyonsElecSupply

Not when the breaker is on the other side of the house.


Twenty bucks more you can throw a breaker in the panel and KNOW you are safe.

Thats just me......

__________________
"Do it right the first time and avoid duplication of effort"

Your AHJ/Inspectors ALWAYS have the final say on ANY electrical code issue.
If in doubt, contact a licensed, experienced, reputable electrician to perform the work.