[firedog061966]

I have about 70 feet of 10/2 wire left over and needed to add a light in my kitchen. I ran out of 12/2 and was wondering if 10/2 would work or not.

[ballengerb1]

Sure it will work, if you did not already own it we'd tell you it is overkill. 10-2 can handle 30 amp and it appears you have ben using 12-2 or 20 amp rated wire.

[tkrussell]

One issue using # 10-2 cable for a 20 amp circuit extension is #10 wire will need use more space in electrical boxes and may or may not be allowed in any existing boxes.

At least 6 inches of wire is required in each box, and if the box is too small, most times the wire is incorrectly cut shorter to get the wires in the box.

[Stratmando]

Save the 10-2 for something else, Temporary Generator power or something. I would stick with the 12-2.
I am a believer of Overkill, but not for this.

[stanfortyman]

I am totally with TK and Strat on this.

There is no valid reason to use this #10 for this. Just get the proper wire, you'll be glad you did.