Electrical Wire Amperage Rating

The tables below are intended to be a general guide for wire size and amp ratings.

Electrical wire amperage rating.

You must use the correct size wire for the current load requirement of the circuit to prevent the wire from overheating. Nfpa 70 national electrical code table 310 15 b 16 size 60 c 140 f 75 c 167 f 90 c 194 f 60 c 140 f 75 c 167 f 90 c 194 f size. Usually a general purpose house circuit is designed for 20. Wire size chart and maximum amp ratings.

60 c 140 f 75 c 167 f awg mm copper. Likewise when the length of the cord exceeds fifty feet there is a decrease in amperage. Awg or kcmil types tw uf types rhw thw thwn. The higher the amperage rating of the circuit the larger the wires need to be in order to avoid excess heat that can melt wires and cause fires.

The number and type of electrical devices connected to a circuit determine the ampacity requirement of the conductor. The amperage rating of a cord is a function of the wire gauge number of current carrying conductors and length of the cord. Ampacity rating copper wire conductors. Table of common electrical wire sizes and amps or fuse ratings residential sec cable other wire ampacities for 1 3 current carrying conductors in cable earth or raceway for 120 240 volt systems sized between 100 and 400 amperes.

When a cord has three current carrying conductors there is a decrease in amperage.