Connections and Understanding [RE-wrenches]

[Ray Walters]

Hi Matt;

We used NM liq flex conduit with duct seal in the same manner you described
with the MC wiring system. We added split 1" PVC conduit to make covers to
tuck the wires against the module frames. We then adapted from the 1" PVC
to the flex and on to the load center/ combiner box. That last section of
1" PVC was not split for the last few inches to make it easy to attach to
the flex. Also, the duct seal section was tucked up under the module
against the frame, so it was very unlikely to be exposed to direct moisture
or sun. Everyone involved much preferred this method to running the MC
wires free.

Ray

 At 07:35 PM 6/4/02 -0700, you wrote:
>William:
>
>I have been meaning to respond to this message you posted a while back.
>
>I do not allow unsupported cable on any of my installations.  I also don't
>allow un-sleeved cables to be run outside the perimeter of the array.
>
>The technique we use is to sleeve the cable(s) with Non-Metallic Liquid
>Tight Flexible Conduit (A product that I condemned for many years but find
>it to be quite suitable for this application) anywhere it extends beyond the
>periphery of the array to a termination point (J-Box/Combiner).
>
>This flex is supported by blocking and secured.  It has a normal connector
>at the termination point but no connector under the array.  We then seal the
>"open" end with duct-seal or splicing mastic to prevent critters and/or
>moisture from entering.
>
>So far it works well, Homeowners are pleased, Inspectors like it and we have
>had no problems with it.  I have used this method for about 2-1/2 years (not
>the tray cable, but sleeving of USE--2 cables).
>
>In the case you describe, I would probably turn the Module J-boxes toward
>one-another so you could run an output to a J-box between every two rows and
>connect the J-boxes to the combiner with EMT.  Does that make sense?  Hope
>so.  I've had a long day.
>
>Best to all!
>
>-Matt Lafferty
>pvpro at attbi.com
>
>William Miller Wrote:
>
>> Friends:
>>
>> I am a died-in-the-wool conduit user.  I have been researching this
>concept
>> of using tray cable.  The samples of tray cable I have seen don't look
>that
>> robust to me.  Maybe I've been sent the wrong samples. They have grooves
>on
>> the outside of the jacket.  How does this seal in a gland connector?
>>
>> Routing of unprotected wire concerns me most of all, for example:  I am
>> currently installing a roof-top system in which the modules are in racks
>of
>> 8, two rows of racks down the length of the roof, modules in strings of 4
>> (48 volt system).  I have a combiner on the right end of each row of 16
>> modules.  This means I have 10 leads to gather at the combiner (4
>> negatives, 4 positives and two grounding wires).  Am I to understand that
>I
>> would run tray cable, unprotected by conduit, 40 feet from the left most
>> module, across the backs of 16 modules, along with the other leads from
>the
>> modules at the far end of the row, all the way to the combiner?  Hey, I'm
>> all for keeping costs down, but I've long ago established standards that
>> don't allow wire flapping in the breeze.  Am I missing some hardware that
>> is available to protect, support and make aesthetically pleasing these
>tray
>> cables?  Does anyone have any pictures I could look at of these tray cable
>> installations, done well?
>>
>> If these concerns aren't addressed by the industry, I feel we should
>> collectively condemn this wiring method.  Unprotected, unsupported  wire
>is
>> the same concept as "knob and tube" wiring.
>>
>> Still wondering........
>>
>> William Miller
>
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