Selection of metal wire is usually based first on a design’s required size and shape, and then on either material types or grades as certain design specifications or application constraints require.

Thermocouple wires are classified into different types based on alloy composition of each wire in the pair. Code letters for wire types are designated by the American National Standards Institute ...

This means gray wire nuts are for the smallest wires, and red ones are for the largest. There are a few main types of wire ...