How do u size wire?

These are the common sizes used in the average home.

AWG #14 - Good for 15 amps (breaker or fuse size).
AWG #12 - Good for 20 amps (breaker or fuse size).
AWG #10 - Good for 30 amps (breaker or fuse size).
AWG #6 - Good for 60 amps (breaker or fuse size).

Wire gauge.

Your question is a bit unclear, but I'll take a stab at it.

Wire has to be sized so that it can handle the current flow through it without causing excessive resistance in the circuit and/or overheating.

Here are some guides to wire sizes:

http://www.rbeelectronics.com/wtable.htm

The answers above that indicate that there are building codes that dictate wire size as a function of amperage (the size breaker to be used in the circuit) are correct. I did this not long ago. I found that the code seemed very conservative; that is, I had to use a large wire for a faily low amperage.

depeds on what your wiring up..

There a charts in the NFPA and NEC that have both where you can cross reference wire Amperage, The material the wire in made out of, how and where it is being used. For simple applications of copper wire you can find a chart in wikipedia under AWG- American wire gauge.


Bill Lutz
Generation 3 Electric, Inc.
http://generation3electric.com
http://electrician-in-philadelphia.blogspot.com/

wire size's are from basic 16 size all the way up to 1 million MCM here is a few ex

16 14, 12, 10, 8, 6, 4, 2, 1, 1/0, 2/0,
3/0, 4/0, 250 mcm etc etc

16 and smaller are typically phone and control systems

Master Electrician 20 years