The fire department wants to know if there is a particular color that could be used to identify conductors coming in from solar voltaic panels. Aside from the white or gray specification for neutral / grounded conductors, I could find nothing in the code. Any ideas??
The code requires the same for DC as AC - the grounded conductor must be white or gray, the ungrounded conductor can be anything other than white, gray, or green. There is also a color coding exception that allows conductors of ANY SIZE in a PV system to be re-identified by tape or paint. This is because all that is commonly available is #10 AWG black wires, I believe type XHHW/RHW-2. For the cables that connect directly to the PV panels you're stuck with that because they use MC-3 and MC-4 connections and I don't think they have those connectors that can be made up in the field. For folks with larger arrays that have JBs on the roof they typically wire nut in the JB and run THWN in 3/4" liquidtight down the side of the house to the inverter.
"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..."
I agree with Fast Eddie and Newenergy posts. The synergy of both electrical and electronics may finally be forced to come together with AC, DC circuit differentiation and isolation.
The White Book lists 'Solar Panel Wire' under Special Purpose (ZMHX) that can fall under UL general catagory basic ANSI standards. The 'listing' mark should appear on the reel or packaging box and not necessarily on the wiring. No mention of color codes are evident. rbj
I sure don't want to get into a debate about color coding wires. But, I do think everyone should know there are probably thousands of industrial plants, and power plants throughout the U.S. that have battery systems in place for various reasons. Red is positive and black negative. Always, except one time on a new power plant, where the young design engineer specified black for positive and white negative. Problems everytime someone went to make a connection or trouble shoot......All that engineer would say - it's only a color, it does not matter. I'll bet those black and white wires added 10% to the cost with lost time - and finally, when the job was all done, the plant electricians went over the whole system with tape - red and black to color code those battery systems.
Oh - The DCS systems - usually 12 vdc - black positive, white negative.