PV Negative color [RE-wrenches]

[Matt Lafferty]

Fellow Wrenches,

Ray's thought of striping the negative conductor is a good one & works well.
You can actually have any conductor striped. I used to do this in the early
days for all of my small conductors.... Buy my wire and have half of it
striped and re-spooled.  This used to cost 5 cents a foot but was invaluable
in terms of time saved pulling wire and terminating it.  Not to mention the
incalculable savings of not having reversed polarities, additional wire
marking, etc.  

I had a seven-color code I used to identify source circuits.... Red = 1;
Orange = 2; Blue = 3; Pink = 4; Violet = 5; Black = 6. For these colors, the
solid color was ALWAYS positive and the striped wire was ALWAYS negative.
The 7th color was Yellow, which I used for series jumpers. I confess that I
cheated on Pink and Orange.... Had to use a black stripe because white
wasn't visible enough. Thank goodness that was back in the day when donuts
worked with building inspectors! ;-)

Most of our projects then were Asi (hi-voltage low-watt modules) so we had
LOTS of source circuits.  The "average" 2kWAC job back then cost about $20
extra for the striping. The time-savings alone made this a no-brainer,
especially since we were paying prevailing wages.  Something about
prevailing wages makes a lot of workers disengage the common-sense gear....
Having as close to a no-brainer method as you can get saves a lot of pain.
The downside is that you have to stock and transport a lot of different
spools of wire with the "many-colors" scheme.

Pray for Sun and a dry hammock!

Matt Lafferty
mlafferty at universalenergies.com


-----Original Message-----
From: Ray Walters [mailto:walters at taosnet.com] 
Sent: Thursday, December 06, 2007 1:57 PM
To: RE-wrenches at topica.com
Subject: Re: PV Negative color [RE-wrenches]



Interesting Discussion. I've always had issues with this especially low
voltage DC using NMB (w/ black, white, & ground) ,then the Poor Homeowner
knows his low voltage from the auto industry: black is negative, red
positive. He looks at black and white and figures "hey at least one color I
know" and hooks the black to neg........ Funny too because most inverter
manus agree with the auto industry on the colors of their main DC lugs: Red
& Black.
I think we have a unique situation here and that applying the same color
coding from AC wiring is problematic.
We try to always use red for positive, and then  I sometimes prefer white
striped tape on black instead of straight white. Code allows us to tape PV
wires smaller than #4. Coded gets its white, homeowner sees black and red
and gets polarity right.
How bout a Special wire just for us: black with a spiral white stripe on it
that not only indicates negative, grounded conductor, but also indicates DC
wiring. There really should be a way to tell just by looking that the wiring
is DC, especially with load centers that house both AC & DC.

Ray


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