What Wire Size Is Required for 50 Amp Service?

Written by sarah celebi | 13/05/2017
What Wire Size Is Required for 50 Amp Service?
Different cable sizes are rated for different ampacity measures. (cables image by timur1970 from Fotolia.com)

Wires are rated for the voltages as well as the wattage they can be used with. A wire with a larger diameter can carry more current than a smaller one. Using the wrong size wire can cause the wire to overheat and burn.

Fifty-amp Aluminum Wire

Aluminium wires are rated differently than copper wires. For a 50-amp aluminium wire, use No.4 AWG. The smaller the number on the wire, the larger the wire diameter. For example No. 4 is bigger in size than No. 6. Aluminum wires come in different types. Types THWN and RHW are the most commonly used ones. No. 6 is only good up to 40-amp.

Fifty-amp Copper Wire

For copper wire, No. 6 or No. 8 THWN can be used. No. 6 copper wire can support up to 55-amp at a temperature of 60 degree Celsius. No. 6 wire is strongly recommended. It's best if a bigger size wire is used.

Voltage Drop

When calculating a circuit, pay special attention to the voltage drop on the wire. Voltage drop is usually caused by the wire resistance. The smaller the wire size, the more the resistance. When selecting a wire size, if the run is more than 100 feet, go one size up.


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