Question: I am moving a minkaire ceiling fan from a flat kithen ceiling to a sloped family room ceiling. The slope of the fm rm ceiling requires that a 1 foot extension be added to the fan to avoid having the blades touch the ceiling. The fan has a receiving unit on it that receives signals from the wall switch unit, which controls various aspects of the fan and it's lights. The extension will require me to add extensions to the wires from the ceiling down to the fan unit. All of the wires on the receiving unit and wall switch are 18 awg stranded wires. I can not find 18 awg at either HD or Lowes. The closest they have is 16 awg. Is it safe to make my 1 foot extensions out of 16 awg wire?

Answer: 
Yes the 16-gauge will work just fine. Make sure your connections are well insulated. P.
You said all of the wires on the receiving unit and wall switch are 18 awg stranded wires. I can not imagine a wall switch wired with 18AWG and carrying anything but low voltage - certainly a code violation in the USA if it is carrying 120V or higher..

The minimum gauge for carrying 120v to a ceiling fan / light is 14awg.

If it is truly a low voltage system (control circuit - like a garage
 door opener wall switch or door bell switch) going up from 18(smaller)
 to 16(thicker wire) should not be an issue.

> 
> If it is not low voltage - you have a bigger problem - the wiring is
>  not in code and is really a fire waiting to happen.
> 
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