Wire Gauges Question

[Richard Wallace]

Originally Posted by dtengineering

...wire gauge is a really archaic way to measure wires. You'd think FIRST would be helping to inspire science and technology by actually using the units of measurement that have been adopoted by scientists and technologists around the world, eh?

Most countries use SI units for engineering, and of course that is the scientific approach.

In my country, we use units that are more convenient for small ratio calculations. American Wire Gauge (AWG) is a good example. 10 AWG wire at standard temperature adds one Ohm per thousand feet to its circuit. Increasing the AWG number by three doubles the per-length resistance; e.g., 13 AWG is two Ohms per thousand feet. This system makes wire size selection much more straightforward than other systems, such as wire diameter in millimeters.

Interestingly, increasing AWG by one unit increases per-length resistance of that wire's circuit by a factor of the cube root of two (~1.26). Wire used to wind electromagnet coils in motors, actuators, and transformers is typically available in size increments of one-quarter AWG, so the per-length resistance ratio of successive (i.e., +0.25 AWG) wire sizes is the twelfth root of two (~1.05946), which musicians will recognize as the ratio of fundamental frequencies of successive notes on an equitempered chromatic scale -- this increment is also called a half-step, or semitone; e.g. stepping from A to A#.

Based on that example and others, I think American engineering units are more like those used by artists, rather than by scientists. I think our system of units promotes creative thought.