MC connectors, warranties and PV system life [RE-wrenches]

[ASAP POWER!]

ASE's large modules have nice twist-lok type connectors and clips along the
inside of the channel framing and down the sides.  They exit the j-box into
the channel frame (out the top) instead of out of the sides of the j-box
with a nice water-tight gland.  The cable insulation is very thick and much
stiffer than any MC's offered, which allow them to tension into the frame
channels where they meet the multiple clips integrated into the frame.  The
nice twist-lok versions click into place and you line up the arrows to be
sure.  An end of string loop back is provided as well which is completely
tucked out of sight.  But when you connect your string's series modules it
still loops out and over the frames of the two modules butted together.  So
one should simply tuck the connection in the channel near a clip and just
the insulated portion of solid lead is looped over.  One could also drill a
large enough hole in the sides of the two modules frames and that might work
even better for tidiness underneath the array.

Peter Duchon
ASAP POWER!

-----Original Message-----
From: keith [mailto:kcronin at lava.net]
Sent: Saturday, February 01, 2003 12:41 PM
To: RE-wrenches at topica.com
Subject: RE: MC connectors, warranties and PV system life [RE-wrenches]


William

Granted the concerns you site in statements can exist, it is not always
the case.  When we do our installation, I buy the UV rated tye wraps by
the bag of 1000.  We have installations that I poke my head in
periodically and have found no abrasions.  We generally don't have too
many leaf problems here in this perpetual tropical environment.
Especially considering if leaves are close enough to an array, there
could be the opportunity for shading!

I am aware of the DC arching you describe. We all are.  It is common
every time you slowly draw your fluke 87 away from a live connection
point and see that trailing arch.

I believe the intent and scope of their evolution came from European
manufacturers.  Perhaps they are more relaxed about design elements.  My
personal feeling is that if these folks design some of the best
automobiles in the world (BMW & Mercedes), this concept can't be all
bad.

Being a licensed electrician tells me it would probably be the most
desirable to have everything in some form of conduit.  Per the last few
posts I have inquired about, I also am trying to lower my installation
costs (without sacrificing quality). If these multi contacts were a bad
thing, I don't see all of the module manufacturers all climbing on
board.  Just recently, I'm sure you know now, Siemens/Shell will have
their modules setup for this configuration.

We have high winds here in the middle of the Pacific.  It is on my radar
screen to make sure things are not flopping in the breeze.  Sometimes
doing conduit (pvc) installations, we have yet another problem.  It is
the expansion and contraction of pvc due to temperature extremes.  If
you have ever seen pvc run horizontally across the side of a home or a
building exposed to sunlight, you can see it become a guitar string and
bow.  Or it can shrink and pop out of its respective junction box.  This
is perhaps due to the fact that an expansion fitting wasn't used on
longer runs.  PVC also gets beat up from UV which makes it brittle and
turns it to a new, lighter gray color.

I am a fan of carflex (flexible conduit).  I again like to keep a
connection a little loose for the expansion/contraction issues. It helps
the wiring to be protected from physical damage and helps with some of
your concerns.

Perhaps the best solution to every concern would be to pool our
collective experience together to make/suggest/design a mounting clip to
properly support the MC cables from panel to panel etc. This would help
with your concern with abrasion, HV fires, etc.

One thing that never seeks to amaze me, are again, the people on this
list.  We are all trying to bring this business to a higher level of
quality and customer satisfaction.

I have an idea that perhaps will reach fruition in the years to come- a
twist lock style connector that will have a tab that lines up when it is
"twisted and locked" in place.  This application is used often in
industrial buildings as well as almost everyone's 5kw generator with the
30 amp "twist lock" male/female connector.


Thanks for the lively, engaging thought process...!!


Keith Cronin
Island Energy Solutions
318 A Kuulei Road
Kailua, Hawaii 96734
808-262-3268 Tel
808-263-0338 Fax
www.islandenergy.net



-----Original Message-----
From: William Miller [mailto:wrmiller at slonet.org]
Sent: Saturday, February 01, 2003 9:17 AM
To: RE-wrenches at topica.com
Subject: Re: MC connectors, warranties and PV system life [RE-wrenches]

>keith wrote:
>
>>  When I review the MC connection concept, I realize it is a good
>> thing.


Keith:

I've used the MC connectors and I'm afraid I can't agree.  I have no
confidence in using unprotected wires on any assembly, especially one
outdoors.  Fastening tray cable to metal structures with wire ties
creates
an abrasion point, rodents chew wire, leaves can catch on them and hold
moisture and the installations look poor.  I'm sure your familiar with
the
propensity of high voltage DC installations to arcing?

I've viewed those installations done by other contractors and by my
crews
and you can see the unprotected cables sagging from the backs of the
modules, regardless of how well they are tied.  This goes against my
instincts and my training.  I fear frequent failures in the not too
distant
future.  Combine this with top down infrastructure and repairs will be
difficult.  I see electricians reaching under modules with dikes
attempting
to cut loose ties to find the bad connection.  How well can they tie
these
cables back up with the modules laying down flat?  Cheap, fast, yes, but
not, in my book, better.

William

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