On a practical note, MC-4 functions fine with THHN inside a weather
proof enclosure. It will not seal, due to the smaller overall diameter
of the cable.
THHN is rated for 90C. It is not sunlight resistant, and should never be
used exposed.
---
On 2021-04-26 23:16, frenergy wrote:
Blake,
Its great to get definitive clarification on this MC4/THHN
issue, we've been using 4-14 Polaris connectors with good results.
Being inside a Nema3 can and having silicone grease in the Polaris
makes for a solid, durable connection. Inspecting some of these that
are now 17 years in the field shows very good condition for the wire
landing in the Polaris and the condition of THWN-2 wire insulation.
We haven't had the best of luck with Buchanans.
Bill
Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
www.frenergy.net
On 4/26/2021 5:41 PM, Blake Gleason 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
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