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/> >> --- end of quote --- >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
