[RE-wrenches] MC4s are listed for THWN, right?
Sindelar Solar
Allan at sindelarsolar.com
Tue Apr 27 21:10:16 EDT 2021
August,
Thank you for this suggestion. I went to the site, and under "Two Sizes
for All Conductor Types" on that page it appears that there's a model
that'll work with 2-10AWG conductors:
"With the 6 mm2 (10 AWG) variant, you can connect all conductor
types – with cross sections from 0.5 to 6 mm2 (2−10 AWG)".
This would contradict what you wrote below, so I'm just checking whether
I missed something.
Thanks, Allan
On 4/27/2021 12:55 PM, August Goers wrote:
> Hi Jason - I noticed that Tesla is using the Wago connectors in their
> Powerwalls. They only go up to #10, but they certainly appear to have
> some advantages such as easy QC inspection, compactness, and price. We
> are in the process of trying a batch of these out, but I hadn't
> considered using them in exterior J-boxes.
> https://www.wago.com/global/electrical-interconnections/discover-installation-terminal-blocks-and-connectors/221
> <https://www.wago.com/global/electrical-interconnections/discover-installation-terminal-blocks-and-connectors/221>
> August
>
> On Tue, Apr 27, 2021 at 10:42 AM Jason Szumlanski
> <jason at floridasolardesigngroup.com
> <mailto:jason at floridasolardesigngroup.com>> wrote:
>
> I'd be interested to hear thoughts on Wago 221-6XX series
> connectors, specifically for THWN to Enphase IQ/DG/TC conductor
> transitions or just THWN splices.
>
> On Mon, Apr 26, 2021, 8:40 PM Blake Gleason
> <blake at sunlightandpower.com <mailto:blake at sunlightandpower.com>>
> wrote:
>
> Corey,
> Thank you! Agreed, the message from Staubli's Eng dept is
> much less confusing (with the exception of the statement about
> THHN tending to be solid vs stranded).
> All -
> What are you folks using to transition from PV Wire to
> THHN/THWN-2 inside a junction box? We used to use split
> bolts, which make an awesome electrical connection, but are
> time-consuming and not easily serviceable. Wire nuts (the
> right ones) are Listed, but never felt reliable for that
> purpose. Same for WAGO levers. I hear about people using
> Buchanan splice caps, but I wonder about trading one set of
> crimping problems for another. And of course, the only
> problem with using THHN in an MC4 is that the compression
> gland may not be as watertight as it is with PVWire, and the
> Buchanans certainly are not watertight. Terminal blocks
> generally aren't listed, definitely aren't watertight, and
> raise inspectors' eyebrows. Why is this so hard for me??
> Best,
> Blake
> Thanks
>
> On Mon, Apr 26, 2021 at 5:19 PM Corey Shalanski
> <coresolar at gmail.com <mailto:coresolar at 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
> <blake at sunlightandpower.com
> <mailto:blake at 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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--
*Allan Sindelar*
allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
NABCEP Certified PV Installation Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
*505 780-2738 cell*
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