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

Sun Feb 2 09:02:10 PST 2003

I may be wrong, but the clips (good idea) look like they are made of spring
steel that rusts (bad idea).

"ASAP POWER!" wrote:

> 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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