PV Negative color [RE-wrenches]

[Jerry Caldwell]

Matt,

Your method sounds interesting, but as Ron mentioned
the white wire signifies a grounded wire - or as one
of my electrical teachers liked to say; grounDEAD.

My teacher also had a story he liked to tell about
when he was a young electrician and was wiring a light
fixture on a three-way switched circuit and got a
hefty jolt while touching the white wire and the j-box
to which the fixture was mounted.  He fell off of his
ladder and broke a bone.  I can't remember which one.

We're not doing automotive electrical work, so I don't
think we should follow automotive conventions.  We
need to work to educate our industry and our
customers, so whoever ends up servicing our systems
can easily understand what they're looking at.

That all said, my humble opinion is that PV systems
powering buildings and other non-automotive sites
subject to the NEC should follow article 200-6(a) and
identify grounded conductors with a white, gray, or
white striped outer finish.

Not all systems ground the PV negative.  Systems using
SunPower modules in the USA for example, should ground
the PV positive.  In this case the positive wire
should be white and the negative wire should be any
color besides green or white.  I prefer red for the
ungrounded PV wire myself.

Best,
Jerry Caldwell


--- Matt Lafferty <mlafferty at universalenergies.com>
wrote:

> 
> 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

NOTICE: Due to Presidential Executive Orders, the National Security Agency may have read this email without warning, warrant, or notice. They may do this without any judicial or legislative oversight. You have no recourse or protection, save calling for the impeachment of the current President & Vice-President.


      ____________________________________________________________________________________
Never miss a thing.  Make Yahoo your home page. 
http://www.yahoo.com/r/hs


- - - -
Hosted by Home Power magazine

To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at re-wrenches.org

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------