On Saturday, January 14, 2017 at 8:10:07 PM UTC-5, wrote:
On Sun, 15 Jan 2017 00:47:29 -0000, "James Wilkinson Sword"
wrote:


A wire that is meant to take 1A will get 19 squared times hotter at 19A. That's very hot.

a wire meant to handle 1a would be between 29 and 30 gauge and you
will never see that used for 120 or 240v.
I pointed out earlier the smallest "fixture wire" allowed in the NEC
is 18 gauge.(1mm)

I've seen 2A wires. What is the difference between 2 squared heating and 19 squared heating?

You may see them over there where you fuse plugs and the chinks use
some pretty cheap wire in those christmas light sets but they do have
a fuse in the plug. They deal with unfused plugs here be requiring a
minimum of 18 ga. That will hold 16a although the NEC limits it to 7.
In a bolted fault, that is more than enough to trip a 20 breaker.
The equipment that will get listed with an 18ga cord will draw less
than 7a, Usually it is just a lamp or a radio.

James can't even apply Ohm's Law. 18g wire has a resistance of .02 ohms
per meter. Put 20A through it and you get 8 watts. That's 8 watts
distributed along a meter of wire. Actually, I guess it's 8 x 2,
since there are two wires in a lamp cord. But 16W along a meter of
wire is very little heat. Go over 20A and the breaker will open.
And we have the everday experience where if this was a real problem,
houses would be burning down from it and it would be addressed in the
code. Obviously it's not happening. Plus, as I pointed out earlier,
a direct, serious short will greatly exceed 20A, tripping the breaker
quickly, before the wire heats up.