[RE-wrenches] MC4s are listed for THWN, right?

[Corey Shalanski]

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> 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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