R624       *Use specified wire colors (mostly). All non-SIGNAL LEVEL wiring with a constant polarity (i.e., except for outputs of relay modules, motor controllers, or sensors) shall be color-coded along their entire length from the manufacturer as follows:

A.      red, yellow, white, brown, or black-with-stripe on the positive (e.g. +24VDC, +12VDC, +5VDC, etc.) connections

B.      black or blue for the common or negative side (-) of the connections

Exceptions to this rule include:

C.      wires that are originally attached to legal devices and any extensions to these wires using the same color as the manufacturer

D.      Ethernet cable used in PoE cables