Wrenches Where did the thought come from about THHN and MC4, insulation is much thicker, releaf is the MC4 matches for USE/PV #10 wire is larger so you would have a poor or no seal. Also THHN is not weather/sunlight resistant. I had an inspector in Hawaii insist on MC4's connecting PV wire to THHN in junction box, he said it has to be done that way, l politely asked if they were approved for that use and there it was "Deer in the headlights" needless to say we kept the barrel crimps and insulators. The industry is going kinda mad, 15 years ago we had to sister up rafters for the lags, now some guys just screw into the plywood with sealant. If you do it right you will do it once, if you cut corners, it will come back to haunt you, or someone else. l know most of you have seen it all too, its our responsibility to help the newer guys on how to do it right. Jerry NABCEP PV inspector
On Mon, Apr 26, 2021, 5:19 PM Corey Shalanski <coreso...@gmail.com> wrote: > Blake, > > In addition to Bryan's notes, here is some unconfusing information > directly from Stäubli's engineering dept: > > The answer is categorically no: *you cannot use THHN wires with MC4 >> connectors.* There are several reasons for this: >> 1. *Certification*: our MC4 connectors are certified to UL6703, >> which only covers UL4703 PV wire or USE2 cable. Any other wire type is not >> covered by our certification >> 2. *Internal validation*: we have no internal testing or validation >> of how MC4 or Evo2 connectors perform with THHN cables. We therefore >> cannot warranty / accept the use of THHN cables with our PV connectors. >> The allowable cables and applications for our PV connectors is clearly >> stated in the assembly instructions. >> 3. *Construction*: THHN cables use very rigid PVC insulators, which >> behave very differently than XPLE or TPE insulators that are the most >> widely used on PV wires. PVC has a very low elastic range and easily >> deforms permanently under load/thermal cycling. It is not a well-suited >> cable for higher temperature or high temperature fluctuating applications >> where compression-type cable seals (i.e. cable glands) are used. Also, >> THHN cables tend to be single-conductor solid core cables, which are >> absolutely not allowed with crimp terminations like the MC4 (or any other >> PV connector on the market for that matter). They also are not allowed by >> UL6703. > > > These comments were forwarded to me by Jeff Wang, who works for Stäubli > North America. > > -- > Corey Shalanski > Jah Light Solar > Portland, Jamaica > > > On Mon, Apr 26, 2021 at 9:23 AM <bl...@sunlightandpower.com> wrote: > >> >> Bryan, >> >> Thank you for the link. I am confused by the "PVC" section you >> referenced. Here's the complete text: >> >> For safety reasons Stäubli prohibits the use of PVC cables. Cables made >>> from PVC can be connected to MC4-Evo 2 since the insulation material of the >>> connector (Polyamide) is suitable to be connected to PVC. PVC cables >>> usually have an upper limiting temperature of 70 °C, in fixed installations >>> sometimes 80 °C. >> >> >> THHN/THWN-2 is made with PVC insulation, so I assume that it falls under >> the category of a "PVC cable." >> >> So, the first sentence seems to say that it's not allowed by Staubli. >> But then the second sentence seems to say that is IS allowed. And then the >> third sentence doesn't seem to be contemplating the most common PVC wire >> type of all (in the US), which is THHN/THWN-2, which has a 90 degree >> rating?! >> >> Can you help un-confuse me? >> >> Thank you! >> Blake >> > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
_______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
