What is mcm wire?

Answer 1

MCM is another measure of wire gauge. It is somewhat confusing but it starts at around 40 gauge being the smallest wire up to the largest gauge of 1. from there you have oughts which is from 1 to 4 (1 ought, 2 ought etc) and then you have MCM which is circular mils. MCM can range from something as small as 250 mcm up to 2000 mcm.

Another Answer

The abbreviation, 'MCM', stands for 'thousand circular mils'. A 'circular mil' is a North-American method of measuring the cross-sectional area of a circular-section conductor (Europeans use square millimetres for conductors of anyshape).

A 'circular mil' is obtained by squaring the diameter of a circular-section conductor, expressed in mils. A 'mil' is one-thousandth of an inch. As the constant, 'pi', isn't taken into account, it should be obvious that a circular mil is, therefore, a figure representing a cross-sectional area, rather than a true measure of that area.

If necessary, in order to obtain a true cross-sectional area, circular mils can be converted into square mils.