[Chuck Schwark]

From the May, 1934 issue of the Philco Serviceman, page 4:

COLOR CODE FOR PHILCO WIRING

Philco has adopted the standard R.M.S. colde code as employed by various other radio manufacturers.
This coloring of wires is held wherever possible, and there are only a very few exceptions where the
standard coloring is not used.
The chart below indicates the various colors of wires and the types of circuits in which these wires are used:
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RED . . . . . . . . . Filaments and odd wires

BROWN . . . . . . . Cathodes and grounds

WHITE . . . . . . . . B+ and screens of output pentodes

WHITE w/BLACK tracer
and/or
BLACK w/WHITE tracer . . . . Plates

GREEN . . . . . . . . Grids and screen grids
__________________________________________________

This may seem like a limited selection, but remember, this is 1934 and manufacturing standards are still being formed, hashed out and adopted among the many, many radio manufacturers of the day.

Every manufacturer's Engineering Department had the "not-invented-here" attitude to overcome as well when the industry was trying to standardize things.