[Rav]

While replacing a non-GFCI combo receptacle/switch with a GFCI one, I noticed that the pigtails feeding the receptacle were worn (old cloth-covered rubber). I'm concerned about their condition, especially since I can't see them once I install the receptacle, so I want to replace them. Two questions:

1. This is a 15 amp circuit, but I'm not sure whether they used 14 or 12 gauge wire originally, and I assume I shouldn't pigtail with 14 if the existing wire is 12. Would a caliper be able to measure it accurately enough, or can a wire stripper be used to determine the the gauge by finding the smallest hole the wire fits into when the stripper is closed, or do I need to get one of those official wire-gauge measuring things?

2. The incoming hot wire and the switch wire are black so I'll use black wire for them. But the neutral also looks mostly black, though with some white haze on it. I don't know if it was once white and it's just black with age, but shouldn't I make the neutral pigtail white wire?

Thanks.

 

[joed]

If the circuit is 15 amp you can use #14.

 

[Rav]

If the circuit is 15 amp you can use #14.

Thanks. What about the wire colors (my second question)?

 

[Jim Port]

The neutral should be white.

Wire strippers can determine the gauge.

 

[Rav]

Is it OK to use 14-gauge stranded wire for the box pigtails? To make it easier to bend and push back into the small box. Such as http://www.homedepot.com/p/Cerrowir...tor-Electrical-Wire-Black-112-3401A/202564770. The GFCI is back-wired (clamp, not stab), and I'll be using Wago 221 lever nuts on the other end. Thanks.

 

[Jim Port]

Stranded is fine.