Hi Dick;
What you're suggesting is actually something I thought would work too:
having totally odd colors that immediately said DC.
IT really would be the best, because if you go in with a meter set to
read AC, and show no voltage, then get your voltage sniffer out, and it
doesn't beep, you think you're double safe, when actually you could get
hit with 500 v dc.
I try and mark every J-box that has DC conductors in it with the DC
voltage. The life I save probably will be my own, as I'm getting more
forgetful with age......
I think one of the problems is that this is actually not a NEW issue;
we are reviving the 100+ year old AC vs DC battle that Edison
Westinghouse, and Tesla, et al. fought before. Factories have AC and DC
on site, and it just amazes me that marking polarity isn't required by
code. We have to mark the bonded conductor, or the high leg in certain
3 phase systems, so identifying DC polarity seems just as important.
I actually really like your purple with a white stripe idea. At one
time I tried to color code for DC voltage too, (Red for 12 v, purple for
24, Orange for 48 v) and even used yellow tape for my PV inputs as they
had a higher V than the battery. Now I just try to label everything
copiously, and have polarity align with my meter.
My biggest problem is still old 12 v house wiring on Romex (white and
black) or which side of those Monkey face outlets should be + or -
...... These days, I just try to switch the circuit over to AC (go
Tesla!)
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 7/1/2013 7:46 PM, Richard L Ratico wrote:
Ray,
I really DO get it. But, after 20 years of mostly working with AC, almost always
terminating black conductors to the left of red conductors: black - red, black -
red, black - red..... I don't think it's much of a mental stretch to see how RED
- BLACK might possibly cause some confusion in the heat of the moment. What say
the negative conductor was required to be purple or purple with a white stripe
when grounded, or some other very infrequently used or even completely new
color, or color combination? Some system that immediately screams "DC!". Would
that not make more sense?
It's still a new world, having DC and AC conductors terminated in the same
system and enclosure. Thanks for the conversation.
And keep an eye on those electricians ;-)
Dick Ratico
Solarwind Electric
--- You wrote:
Dick;
I'm not advocating for a color coding system I invented. It is not
dependent on how a wrench's head is wired; its corresponds to how his
meter is wired. This is simply combining NEC compliance with almost
universal common practice (batteries, automotive, forklifts,
multimeters, battery based inverters)
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 6/30/2013 9:58 AM, Richard L Ratico wrote:
Ray,
Conductors can be mislabled regardless of the system used. The accident you
described had nothing to do with conductor color or labeling. It was caused by
a
gross violation of sound electrical procedure and plain common sense. Your
electricians failed to check for correct polarity before making their
terminations.
I grant your system works for you and could for others. But until the NEC
forces
us all onto the same page, an argument can be made that any coding system is
as
confusing as another. Pardon the pun, it depends on the way a wrenches's head
is
wired.
Dick Ratico
Solarwind Electric
--- You wrote:
We have standardized on DC markings White negative and Red positive.
Chris Mason
Comet Systems
Anguilla (264) 235-5670
St. Kitts (869) 662-5670
skype netconcepts
NABCEP Certified Solar PV InstallerTM
Renewable Energy Systems professional
Generac Generators Factory technician
On Jun 29, 2013 8:30 PM, "David Katz" <dk...@aeesolar.com> wrote:
Watch out for accountants who become installers. They always thing red
negative and black positive.
David Katz
Sent from my iPhone
On Jun 28, 2013, at 5:40 PM, "Ray Walters" <r...@solarray.com> wrote:
Richard, when you use your Fluke 87 to measure Vdc, black is negative,
red is positive. The black is labeled common because the meter can also
be used for current measurements. (I have a Fluke 89)
When you start using black wire for positive, it may be allowed by code,
but there just isn't a good reason for it.
Its just too easy to make a mistake, and its just too easy to adhere to
the multimeter convention and keep it safer.
I have personally watched seasoned electricians argue color coding with
me, then minutes later get mixed up and wire two 10 module strings in
series, because they forgot for a moment that they were working on a
positive grounded system. The result was an almost 1000 v arc that
jumped an opened fuse holder (only rated to 600 vdc) and started a small
fire in the inverter, before I disconnected it at the array.
Please give one example where leaving positive unmarked with black wire
makes more sense than taping it. Colored electrical tape, and label
tape are much cheaper than inverters and people. THHN, USE, and PV wire
can all be purchased in red, white, and black. (which saves time with
multiple home runs)
Its not code yet, but it's good sense, all the way back to the color
coded jumper cables you might have in your trunk.
I have discussed this with many electricians over the years, but
eventually every single one sees that's its really easy, no cost, and
still code compliant to make things safer.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 6/28/2013 2:49 PM, Richard L Ratico wrote:
Respectfully:
My Fluke 87 does not use this convention. Black is labeled the COMMON
terminal,
the red terminal is labeled according to function, not polarity.
Battery based
inverter manus. using this convention typically provide BOS enclosures
with OCP
for only one inverter conductor. This requires the other conductor to be
grounded and colored white or gray. Therefore IMHO the manus. should
use only +
or - to identify inverter terminals. Many, if not most, battery
companies do
this already. Mr. Wiles is, of course, welcome to his opinion.
I would suggest we stay with the NEC required use of any color other
than white,
green or gray for ungrounded conductors. This gives installers some
flexibility.
It also encourages the guy on the hot roof or the gal in the stuffy
mechanical
room to check and double check, maybe triple check polarity, as they
should be
doing anyway. I do like the practice of enhanced identification of
conductors in
positive ground systems.
Dick Ratico
Solarwind Electric
--- You wrote:
The convention of red for positive and black for negative is not just
automotive. It is also used by all battery based inverter manus, all
battery companies, and all multimeters.
John Wiles also agrees;
red = positive, black = negative for ungrounded systems
red = positive, white = negative for negative grounded systems
white = positive, black = negative for pos grounded systems.
I take it a step further, and use white label tape with red lettering
that says "+ positive ground + ",
because I've seen so many problems with positive grounded systems, and
people not getting polarity correct.
All of this is NEC compliant, and follows standard conventions.
Make it easy on yourself and your journeymen on a hot roof, and have
your color coding match their multimeter.
You might save an inverter or even a life.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 6/28/2013 12:09 PM, Allan Sindelar wrote:
On 6/28/2013 11:47 AM, a...@aramsolar.com wrote:
And of course Red for positive and black for negative.
Most building departments have not pick up on this yet. But they will.
Aram
Where does "of course Red for positive and black for negative" come
from, please? I only know it as an automotive standard that has often
caused confusion when used by DIY offgridders in years past, as black
thus could represent either positive or negative in a DC conductor
pair.
Is there yet a convention for ungrounded arrays? While red and black
are technically correct as ungrounded current-carrying conductors, use
of this color convention could cause as much confusion as resolve it
in the future. How about "black and black" or for that matter "yellow
and orange" (if supplied by manufacturers) for ungrounded arrays?
Thanks, Allan
*Allan Sindelar*
_Allan@positiveenergysolar.com_ <mailto:al...@positiveenergysolar.com>
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*, a Certified B Corporation^TM
3209 Richards Lane
Santa Fe, New Mexico 87507
*505 424-1112 office 780-2738 cell*
_www.positiveenergysolar.com_ <http://www.positiveenergysolar.com/>
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