Uncle Monster writes:
On Sunday, September 27, 2015 at 10:10:58 PM UTC-5, Seymore4Head wrote:

You are not supposed to use #14 at all if you have a 20A breaker.

You're right but I've never seen a 20 amp breaker not trip when a #14 wire =
was connected to it and shorted.

It's not short-circuits that one worries about, but rather the
heating caused by the higher resistance of the smaller diameter
conductors over the longer term.