Whenever a circuit is extended or rewired, or when any new circuit is installed, it is critical that the new wiring is made with wire conductors that are correctly sized for the circuit's amperage rating. The higher the circuit's amperage rating, the larger the electrical wires need to be to avoid excess heat that can melt wires and cause fires.
The wire is sized by the American Wire Gauge (AWG) system. Wire gauge refers to the physical size of the wire, rated with a numerical designation that runs opposite to the diameter of the conductors. In other words, the smaller the wire gauge number, the larger the wire diameter. Standard sizes include 14-, 12-, 10-, 8-, 6-, and 2- gauge wire. The size of the wire dictates how much current can safely pass through the wire.
If you have shopped for electrical wire, you may have noticed that there are many types and sizes of wire to choose from. Different types of wire are intended for various uses, but knowing the correct wire size or gauge is key to making the right choice with any of these wire types. The following article explained the wire sizes and how to check the numbers.
Electrical Cable Parts
Whether a home or a commercial building, the wire and cable aisle is a very messy place. Before determining the size of the wires, you need to learn how to identify different cable types and their uses to ensure that you find the cables you need and the wiring safely.
Cable And Wire
People often use these terms interchangeably and are often confused by these two types, but there is a difference you should know:
- Cable is an assembly of two or more wires in a single jacket.
- Wires are the individual insulated or bare conductors inside the coat.
Wire gauge refers to the physical size of the wire. You can find the number on cables, the rated with a numerical designation that runs opposite to the diameter of the conductors. The smaller the wire gauge number, the larger the wire diameter. The most common sizes you'll find in residential work are 14-gauge and 12-gauge. Larger appliances such as electric stoves, water heaters, dryers, and central air units will often use 10-, 8- or even 6-gauge wire.
Electrical cable current is measured in ampacity, and each wire gauge has a maximum safe carrying capacity. For standard non-metallic (NM) cable, these amperage capacities are as follows:
|Amperage Capacities for Standard Non-Metallic (NM) Cable|
|14-gauge wire||15 amps|
|12-gauge wire||20 amps|
|10-gauge wire||30 amps|
|8-gauge wire||40 amps|
|6-gauge wire||55 amps|
|4-gauge wire||70 amps|
|3-gauge wire||85 amps|
|2-gauge wire||95 amps|
Cable by the Numbers
An electrical cable is classified by two numbers separated by a hyphen, such as 14-2. The first number denotes the wire's gauge, and the second represents the number of wires inside the electrical cable.
Wire Size Guide
It is vital to know the sizes in the cable to ensure it carries an appropriate amount of current securely. The gauge rank also determines the resistance of the wire and its weight per unit length. Each wire size has a maximum current limit that a wire can handle before damage occurs. It is essential to pick the correct size of wire so that the wire doesn't overheat. The following is a wire size chart that shows allowable ampacities in different situations.