Choosing the Correct Wire Gauge for Circuits

All of us live with clusters of wires. Without these wires, we wouldn't have lights, dishwashers, computers, mobile phones and all those modern conveniences we rely on. These wires conduct electricity, and in our homes, we need the right thickness of wire to power the things we need to keep our household going. You won't need the same wire gauge to power the toaster that you'll need to power the oven, for example.

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Choosing the Correct Wire Gauge for Circuits

What is a Wire Gauge?

Wire is made to a specific group of sizes designated by gauges. Most copper and aluminum wires for homes are measured from 6 to 18 gauges, often, but not always, in even numbers. And, although this sounds wrong, the higher numbers actually mean a smaller wire size. So that's why an electric range needs a 6-gauge wire, while your electric lamp may use a 14-gauge copper wire. Wires that are the correct gauge will not get hot when carrying electrical currents to the item that's being powered. You should never feel heat coming from your wires. If you do, then you'll need to use a higher-gauge wire, or you run the risk of an electrical fire.

Choosing the correct wire gauge for wires that run from your electrical distribution panel to various appliances and electrical outlets is crucial. Your electrical distribution panel controls the amount of circuits, or amplifier circuits, that are distributed to various electrical outlets. This is why your stove and refrigerator are usually plugged into outlets specifically wired for those appliances. They require more current, or amplifier circuits, or amps. If you try to power an appliance using a circuit that is overloaded, the circuit will shut off and the appliance won't work. You can power an electric lamp with a circuit that's actually meant to run a clothes dryer, but you'll be using much more electricity than you need, and you'll be wasting money.

Correct Wire Gauges for Circuits

So for lighting and other minor household electrical uses, you will have a 15-amp circuit with 14-gauge copper wire, or 12-gauge aluminum wire. For small kitchen appliances, like your coffee maker, toaster and other countertop appliances, you'll want a 20-amp circuit with a 12-gauge copper wire (10-gauge aluminum). Lots of new homes now use a 20-amp circuit for general electrical receptacles. For an item as large as an electrical water heater, you'll need a 30-amp circuit with 10-gauge copper wire (8-gauge aluminum). For a power-hungry appliance like the clothes dryer, you'll need a 40-amp circuit with an 8-gauge copper wire (6-gauge aluminum). And for an electric range, you'll need a 50-amp circuit with a 6-gauge copper wire (4-gauge aluminum).

Ground Wire Gauge

Your utility carrier supplies power to your home in the form of volts and amps, using either copper or aluminum wiring. There is a slight difference in the amount of currents copper versus aluminum wires can carry, which is why the gauges are slightly different relative to the circuit.

Most houses built today are built with a minimum of 150 amps of service, and 200 amp service is common. Older homes may have 60 to 100 amps, although because of more demand for electricity, power supply to an older home is often increased to 150 or 200 amps if that home is renovated.

Older homes often had fuses, but today, homes are built using circuits, which "break" when overloaded, causing the circuit breaker to shut off. Circuit switches can be flipped back on, while fuses had to be replaced.

So copper ground wires for a 100-amp service require an 8-gauge copper wire. For a 125-amp service, a 6-gauge copper wire is needed. For a 150-amp service, a 4-gauge copper wire is needed. For a 200-amp service, a 3-gauge copper wire is needed.