[RE-wrenches] double insulated wire

David Katz dkatz at aeesolar.com
Sat Jun 29 17:30:36 PDT 2013


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" <ray at 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, aram at 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 at positiveenergysolar.com_ <mailto:Allan at 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/>
>> --- end of quote ---
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