DC Module Wiring Color Codes
DC Module Wiring Color Codes
"Back in '97 - that is 1897- when the first edition of the Code was being drafted, Thomas A. Edison was generating power. And it was direct current (dc) power, not that alternating current (ac) stuff those heavy, costly transformers developed by Westinghouse and/or Tesla. AC came later, and the early code dealt with direct current, including color codes for that dc power. If the conductor is a grounded circuit conductor, the insulation or marking on larger conductors must be white or gray. If the conductor is an equipment grounding conductor, it must have green or green with yellow stripe insulation or be bare.
Those color codes apply to both ac and dc electrical systems. There is no special color code for dc systems. Nearly all past PV systems and those being currently installed are grounded systems and one of the conductors in the dc parts of the system should be white. PV installers insisting that red is positive and black is negative are to be relegated back to their electronics workbenches where such color codes originated.
Yes, in the future, we will see the installation of ungrounded PV arrays (see 690.35) that will be used with transformerless inverters, and those systems will not have a grounded PV dc conductor. Then red and black conductors may become more common; but on the current grounded systems, they are incorrect..."
-IAEI Magazine, March/April 2008
(Common PV Code Violations)