Before we proceed to discuss the Types of Wires For Electrical Outlets let briefly consider how wire are being measured.
The gauge of wire used for electrical outlets and circuits is a measure of the diameter of the wire using a standard wire gauge.
Therefore, a larger gauge of wire refers to a wire with a small cross-sectional area or small-diameter and vice versa; this is because the concept of gauge is obtained from the size or number of wires you can fix through a standard opening use worldwide to measure the diameter of a wire.
As shown above in the image the diameter for a standard 12-gauge copper wire is usually 2.05 mm, while that of 14-gauge copper wire is 1.63 mm. A larger cross-sectional area of wire generates low resistive heat than a smaller wire, and can allow the flow of more current without overheating the wire.
How To Select Gauge of Wires For Electrical Outlets?
12-Gauge Vs 14-Gauge Wire
As the wire size amp rating chart at Cerrowire states, under normal household temperature conditions, the maximum current rating for a 14-gauge wire is 15 amps, while that for a 12-gauge wire is 20 amps. It’s OK to wire a 15-amp light circuit with a 14-gauge wire to save a bit of money and make the wiring job a bit easier. But the decision between 12-gauge or 14-gauge wires for electrical outlets isn’t always as straightforward for a couple of reasons: some appliances draw more than their running current when they start up, and circuits with many electrical outlets can experience a significant voltage drop if a large number of receptacles are in use at the same time.
You can avoid both problems by wiring the electrical outlet circuit with a 12-gauge wire, which is optional if the controlling breaker and all the outlets are rated for 15 amps. If the breaker is rated for 20-amps, however, you don’t have a choice, because the electrical wiring code does not permit you to use a 14-gauge wire on a 20-amp circuit. You must also use a 12-gauge wire when connecting an outlet rated for 20 amps, as many GFCI outlets are, even if the appliances you plug in are rated for only 15 amps.
When wiring a new building, it’s always advisable to arrange lights and power outlets on separate circuits in the distribution panel, which guarantee that if there is a failure in any of the power outlet circuit, the light in your building won’t go off. As long as each lighting circuit is not overloaded, you can terminate and control such a circuit with a 6-15amp miniature breaker, while using a 14-gauge wire. On the other hand, a power outlet circuit controlled by a 20-amp breaker usually requires a 12-gauge wire.
Sizes of wires for 240-Volt Electrical Outlets
Most houses have one or more 240-volt outlets to service an electric dryer, stove or water heater. The wire gauge depends on the current rating of the outlet and of the breaker, which, according to code, must be the same.
The minimum wire size for a 30-amp, 240-volt circuit is 10-gauge, but to prevent poor performance because of voltage drop, you should consider upgrading to 8-gauge if the outlet is far from the panel. For a 50-amp circuit, you need a 6-gauge wire at a minimum.
below is an image showing wire gauge with their respective current rating
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