How To Choose the Best Extension Cable

A variety of factors will affect the current bandwidth and usage range of an extension cord. We will interpret it from the aspects of specification, power rating (Amp/V/W), cord length and voltage drop.

1. Gauge grade

Cable gauge is the thickness or diameter of the wires inside the extension cord. This thickness is measured by an American Wire Gauge (AWG) number: the lower the number (000 to 40), the thicker the wire. For most home and outdoor use, look for a gauge between 10 and 18 AWG. Typically, you can find the cord's AWG number (also called the wire gauge rating) on the cord's jacket, which is the thermoplastic layer that surrounds and protects the wire (see "Sheath Strength" below). The gauge is usually paired with the number of conductors inside the cord. For example, a 16/3 wire means a 16 gauge wire with three wires inside.

2. Rated power

In addition to the meter's rating, you'll often see three numbers related to an extension cord's power capacity: amps/volts/watts. Amperage (amps) measures the amount of electricity or electricity flowing through a conductor, such as the wires inside a power cord. Voltage (volts) measures the pressure or resistance of that current. Watts measure the power produced (volts times amps). These numbers are critical because plugging a high-powered device into an under-rated wire can cause the wire to overheat and catch fire.

3. Wire length and voltage drop

While some extension cords may be longer than 100 feet, extension cords between 1 and 100 feet are the most useful and popular for work within the home and at home. The length of the wire also affects the amount of voltage lost over long distances due to resistance - the longer the wire is extended, the more voltage is lost, a characteristic called "voltage drop". To avoid voltage drops, use the shortest extension cord for a given task. A longer wire has less capacity (larger voltage drop) than a shorter wire of the same gauge. For example, a 16-gauge extension cord with a length of less than 50 feet can provide up to 1625 watts of power to a device, while a 16-gauge cord with a length greater than 50 feet can reduce the power and only power a 1250W device.