Wrenches,
I am normally a lurker on the List, but I would like to add a fact
observation and a personal preference to the topics raised by this
discussion.
First, THWN does have PVC as its primary insulation, but it is sheathed
in Nylon which is a polyamide plastic. Therefore the compatibility with
MC4 connectors should be polyamide being squeezed by the restraining
bushing in the MC4, not PVC.
I prefer Buchanan copper crimp connectors when splicing PV wire to
THWN-2 in a roof junction box. The bared wires should be lightly doped
with NO-OX-ID A-Special grease
https://www.sanchem.com/electrical-contact-lubricant.html before
sleeving and crimping with the crimp sleeve to repel entry of moisture
and corrosive gasses into the wire joint. I consider the crimped joint
to be superior to any screw-clamped joint that would be made in a
Polaris style connector. I also drill weepage holes in the bottom
corner of the junction box to mitigate any collection of water.
Eric Stevens, Vermont Made Energy
On 2021-04-28 18:16, re-wrenches-requ...@lists.re-wrenches.org wrote:
I think the biggest issue with poor connections on the Polaris type blocks
is not stripping enough insulation off the wire. They need much more
stripped off than other types of connectors. With too much insulation
remaining, the screw tightens on the insulation, and the electrical
connection is just some loose copper tickling the inside of the barrel.
You wouldn't notice it at first with testing, but it would definitely start
to over heat over time. Might catch it with a FLIR though.
What other connectors are 1000 v rated? This seems like more an issue of
having the manufacturer's retest to 1000v. I can't imagine those blocks
not being able to handle 1000v, but.....
Ray Walters
Remote Solar
303 505-8760
On 4/28/21 11:27 AM, Corey Shalanski wrote:
Chris's reminder is a good one?the 600V rating of most insulated
"multi-tap" connectors pretty much limits their use to residential systems.
I would also keep in mind that those connectors generally have a torque
spec. I've definitely seen examples of meltdowns caused by poor
terminations - either the compression screw isn't torqued properly or the
conductor isn't fully inserted. To help eliminate the latter case, we used
to favor the Burndy models (e.g., BIT4
<https://www.hubbell.com/burndy/en/Products/Power-Utilities/Connectors/Lugs-Terminals/Bolted/Vinyl-Insulated/BIT4/p/2021315>)
because they had a transparent case; I see that Polaris also now offers
transparent models (e.g., IT-4C
<http://www.nsiindustries.com/catalog/nsiproducts/polaris-mechanical-connectors/polaris-vision-tap/it-4c>
).
--
Corey Shalanski
Jah Light Solar
Portland, Jamaica
On Wed, Apr 28, 2021 at 7:38 AM Chris Sparadeo <sparadeo.ch...@gmail.com wrote:
Keep in mind that Wagos, Polaris lugs, Multi-tap Burndy lugs are rated
for 600V. I can see this being a possible use for MC4 connectors in a
higher voltage splice scenario, because of their 1000V/1500V ratings.
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Today's Topics:
1. Re: MC4s are listed for THWN, right? (Blake Gleason)
----------------------------------------------------------------------
Message: 1
Date: Wed, 28 Apr 2021 15:13:51 -0700
From: Blake Gleason <bl...@sunlightandpower.com>
To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
Subject: Re: [RE-wrenches] MC4s are listed for THWN, right?
Message-ID:
<cajvvaurnwuhvtne+qtqvmoc7ksa1dob36l2utdyyfej756g...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Great discussion, all. Thank you.
For 1000V (where we also tend to favor MC-style connectors), we are
connecting PVWire to 1000V-rated XHHW-2 (which is not PVC), and always
inside a 3R box.
Blake
On Wed, Apr 28, 2021 at 9:00 AM Ray <r...@solarray.com> wrote:
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