# New Inspectors I hope this helps AWG Wire Sizes vs Available Current

**AWG Wire Sizes vs Available Current **

This is a small graphic that shows a number of different wire sizes in AWG compared the amount of current the wires can handle. An easy way to visualize wire size AWG and current rating.

Are you sure about the amperage ratings?

(Good pick up) 14 is 15amps and 12 is 20amps. Nice work!

IEEE Standard 835, IEEE Standard Power Cable Ampacity Tables
IEEE Standard 848, Procedure for the Determination of the Ampacity Derating of Fire Protected Cables
ICEA P-54-440, NEMA Pub. No. WC 51 - Ampacities of Cables in Open-Top Trays.

The National Electrical Code [NEC] requires their own cable sizing for premises wiring.
Refer to the NEC rules to determine building wiring, as this page relates to electronic equipment wiring.
For reference, the ampacity of copper wire at 300C for common wire sizes
14 AWG may carry a maximum of 20 Amps in free air, or 15 Amps as part of a 3 conductor cable.
12 AWG may carry a maximum of 25 Amps in free air, or 20 Amps as part of a 3 conductor cable.
10 AWG may carry a maximum of 40 Amps in free air, or 30 Amps as part of a 3 conductor cable.
8 AWG may carry a maximum of 70 Amps in free air, or 50 Amps as part of a 3 conductor cable.

The wire fusing [melting] current is based on the material the wire is made of, the diameter of the wire and the melting point of the the material.
The wire fusing current of a wire is provided in tables as constant current or as [a larger] current for some given amount of time.
I found this formula used on a few different sites [un-verified]; I=Ad(3/2) @ d is in inches, A is a constant: A = 10,244 for Copper. A = 7,585 for Aluminum.
I have listed a number of values for fusing current in the table above, for selected AWG sizes.

Not Exactly…According to Table 310.15(B)(16) or 310.16 for all those not having a 2011 NEC. The actually ampacity of a 14 AWG is 15A under the 60 degree column but is 20A under the 75 degree column and the real full ampacity of a 14 AWG with the proper insulation could be 25A on a 14 AWG…at the 90 degree column. Same kinda thing for 12 AWG as well but with 20A ,25A and 30 respectfully. The kicker is we are limited by the ratings of the terminations and those tend to be at 60 or 75 degrees.

However, we are limited by 240.4(D) on 14, 12 and 10 AWG conductors due to overcurrent protection limitations. Just remember that in some occasions you could indeed have 20A on a 14 AWG and so on…as permitted by 240.4(E) or (G).

Just some info…for what you all deal with in residential settings…yes, 14 AWG should be 15A, 12 AWG should be 20A and 10 AWG should be 30A.