Types of Wire/Cable

Types of Wire/Cable

Wire diameter is measured using a term called gauge. The gauge of a wire and its actual thickness are inversely related. So the larger the gauge, the thinner the wire. The smaller the gauge, the thicker the wire. This means a 30 gauge wire is very thin and a 4 gauge wire is quite thick. 

The thickness of the wire relates to the ability of it to carry electricity. Thin wires are not good at conducting high loads. This means thin wires can heat up and melt when exposed to high voltage or currents. Thick wires are much better for conducting high loads. This is why the battery cables in a vehicle are very thick while wires in small electronics can be very thin.

Wires also come in stranded and solid varieties. Stranded wires have several thinner wires twisted together. This allows for the overall wire to have more flexibility. Solid wires have a single conductor and are less flexible than the stranded wires.

Most electricians do not often use individual wires. That may sound weird to hear, but most electrical connections need three or more wires at a time. So, instead of using three single wires, electricians use cable. A cable is a group of wires with a plastic or rubber sheath on the outside. This makes it easier to install, handle, and generally use. At the ends of the cable, electricians will strip the outside sheath and then strip individual wires to make electrical connections.

Generally, electricians will use cable. You may hear cable referenced as “Romex.” Romex is the trade name owned by the company that created thermoplastic sheathed cables. Many people may use the term “Romex” when they mean any electrician cable, similar to how “Kleenex” is used colloquially for any tissue. In this course, we will refer to a sheathed bundle of insulated wires as a cable.