PV Negative color [RE-wrenches]

Thu Dec 6 19:22:31 PST 2007

I think that a solidly grounded conductor should be
white, or not, BUT when working with systems using a
ground fault breaker or fuse and is therefor a fused
grounded conductor, it should not be white.  If a
ground current makes the wire hot, don't call it
grounded.  If the only way it can become hot is when
it is broken then it can be called grounded.  

In the 2008 code the grounded conductor must be
identified which circuit it belongs to by grouping or
tagging, so Matt was ahead of his time.  I think the
grouping requirement is to prevent hazards when
servicing.  
Darryl
--- Jerry Caldwell <solarcowboy at yahoo.com> wrote:

> 
> 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
> 
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> 
>      
>
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=== message truncated ===

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