Wire Gauge Requirements

Be sure to run the right size wire to the fuse panel.

Wire gauges can be confusing to the electrical novice. The wire gauge determines the amount of current that can flow through the wire. While it might seem logical to associate thicker wire with a larger gauge number, it is actually the opposite.

How it Is Measured

Wire thickness is based on the American Wire Gauge (AWG), which dictates that the thicker the wire, the lower the gauge number. Standard 15-amp wire is listed as 14 gauge, while an electric range may require 8 gauge wire to allow for 40 amps. Another measurement consideration is the number of wires. Wire that is designated 14/2 is rated for 15 amps and has one hot and one neutral wire, while 14/3 is rated for 15 amps and has two hot and one neutral wire.

Considerations for Use

The wire gauge required in any application is dependent on the breaker or fuse used and the appliance to which the wire supplies power. The size of the wire determines the amount of current that can flow through it and its ability to overcome resistance. Long runs may require the use of a smaller gauge.

Possible Dangers

The wire gauge must match that of the breaker or fuse to which it connects. If the breaker is designed for 40 amps but the wire is designed for 20 amps, a fire risk arises because the breaker will not trip even though the wire is overheating.

Matching the Appliance

The wire must match the requirements of the appliance. An electric range will not operate using the same wire as the one used to power the lights.

References

• Los Alamos National Laboratory: CDC Workplace Safety and Health: Electrical Safety Student Manual
• Bob Vila: Glossary of Terms: Wire Gauge