mixing wire gauges

[gsmurray24]

I'm new to the Forum, but have a quick question on electrical do's and don'ts. I am finishing an area of my basement, and have a 15 amp run from the panel to a gang box. The run is 14/3 wire. From the gang, 14/3 wire exits to one receptacle in the garage. I want to run one more receptacle from the gang to an outlet in my finished area. Can I use 12/3 wire for this short run of 6 feet, or should I go buy a 25' box of 14/3 and use that? It seems silly, but can 12 gauge wire and 14 gauge wire be used together on a 15 amp circuit? Thanks.

[mdshunk]

While mixing wire gauges is not normally done, there's nothing that prohibits you from using the heavier #12 wire on the 15 amp circuit. You may never use lighter #14 on a 20 amp circuit, but you don't want to do this anyway.

If you wanted a truly "professional" job, buy some more #14 and continue the circuit with the same gauge wire. If cost or convienence is an issue, there's no real reason why you can't use the #12 you already own.

Some of the home centers have the 1000' rolls of Romex on their "ferris wheel" that they sell cut lengths off of. Maybe you could just buy 6 or 8 feet of the #14, so you wouldn't have any leftover? Just a thought.

[gsmurray24]

Great, thanks for the information. Basically, I can go larger (actually, smaller number, larger wire), but never smaller, which makes sense.

I am stopping at the HD on the way home to get a small roll of the 14/3- why be cheap for less than $10 and do it not right. I've got the walls open, I'll pull the 12/3 out and use the 14/3.

[suemarkp]

Are you really using 14-3? Does this have 3 insulated wires or two? Are you trying to have switched and unswitched receptacles?

A simple normal house circuit would use 14-2 with ground or 12-2 with ground. The bare wire is not typically counted in a cable, but it is counted in cords when insulated.

Mixing gauges is as the others have said. Doing where you propose is better than doing it at the cable run from the circuit breaker panel. It is most important that the breaker not be excessive for the circuit, and most electricians will assume the circuit is sized per the wire in the panel. Having larger wires past that first one is fine, but smaller is not.

[gsmurray24]

My bad, it's 12/2 and 14/2. Just plain old ordinary house wire. But thanks for the input.