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 >
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