[RE-wrenches] Factory Over bent Wiring

[bob at midnitesolar.com]

Ray is coming at this from an electricians viewpoint. He is correct if 
talking about wiring outside of a UL or ETL listed product.

The reason for wide radii in wiring is so the wires can be rerouted and 
terminated a few times.

8 times the diameter is a very large bend radii and would never fly 
inside a product, so why can a manufacturer do it?

Copper has the tendency to work harden when bending back and forth. That 
will damage the current carrying characteristics of a wire.

Bending a wire once does not work harden them. The insulation can get 
scrunched depending on the actual bend radii, but it is

only cosmetic after one tight bend. There are no actual cracks that 
would jeopardize the insulation integrity.

We have investigated this and determined it to be cosmetic in nature for 
a single bend. That said, I don’t like it either

because it makes installers nervous and doesn’t look good. The tight 
wire bends are no different from putting tight bends

on a sheet metal copper busbar. We do this all the time and always have. 
Testing shows that it does not constrict electrical flow.

If you straighten that same copper busbar and bend it again, it is 
likely to break in half. That is work hardening to the extreme.
So, there is no violation from tight wire bending inside a listed box. A 
listed box does not have the same restrictions as the NEC.

Believe me, I too do not like zero radii bends and we have custom made 
pliers that give the wire a gradual radii, but that is cosmetics only.

The wire is not actually damaged unless you straighten it up and re-bend 
it. We do not do that!
Thanks,
Robin Gudgel
MidNite Solar



On 10/15/2018 11:27 AM, Will White wrote:
> NEC doesn't apply to the interior components of a UL listed device 
> although I do see your point. I'm assuming they designed it taking 
> that bend into consideration.
>
> On Mon, Oct 15, 2018 at 1:20 PM Ray <ray at solarray.com 
> <mailto:ray at solarray.com>> wrote:
>
>     Greetings;
>
>     I've noticed several of the factory wired power panels over the
>     years from Magnum, Outback, Midnite, Etc are not compliant with
>     NEC 300.34 wire bending radius. (Radius should not be less than 8
>     times the diameter) Basically they should look like sweep bends in
>     PVC conduit, not plumbing.  Here's a pic from a recent Magnum system
>
>     You can see the kinks in the insulation on the inside of the bend,
>     and the color fading on the outside from being overstretched. 
>     Some might think this is neat work, but its actually permanent
>     wire damage and a code violation. Imagine the strain on the copper
>     inside.
>
>     Midnite is very proactive and has improved, I ask that Magnum do
>     the same and soon.
>
>     Thanks,
>
>     -- 
>     Ray Walters
>     Remote Solar
>     303 505-8760
>
>     _______________________________________________
>     List sponsored by Redwood Alliance
>
>     List Address: RE-wrenches at lists.re-wrenches.org
>     <mailto:RE-wrenches at lists.re-wrenches.org>
>
>     Change listserver email address & settings:
>     http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
>     List-Archive:
>     http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
>     List rules & etiquette:
>     www.re-wrenches.org/etiquette.htm
>     <http://www.re-wrenches.org/etiquette.htm>
>
>     Check out or update participant bios:
>     www.members.re-wrenches.org <http://www.members.re-wrenches.org>
>
>
>
> -- 
> *Will White*
> Curriculum Developer
>
>
> e: will at solarenergy.org <mailto:will at solarenergy.org>
> w: www.solarenergy.org <http://www.solarenergy.org/>
> p: 802-272-3092
>
> PV Installation Professional
> # 093006-34
>
> /FACT: If we covered 0.33% of the earth with solar panels, we could 
> power the world with renewable energy./
>
> Do you envision a world powered by renewable energy? Be the change 
> <http://solarenergy.org/donate>.
>
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches_lists.re-wrenches.org/attachments/20181016/568d2adb/attachment.htm>