[Elecraft] Why black is the hot wire

[David Robertson]

At the early part of the 20th century, when electricians were wiring houses
(knob and tube), the color of the electrical wire was only black. The power
companies found that one side of the power feed (center tap on 220) to the
house or building had to be grounded to prevent voltage buildup on the
power lines. In order for the electricians to keep track of the grounded
side (neutral)  of the power feed they painted the grounded (neutral) wire
white. Soon after the wire manufacturers started making both black and
white wires so the electricians now could safely wire buildings without
resorting to painting the ground wire white.

73
-- 
Dave Robertson KD1NA