After market J-boxes [RE-wrenches]

William Miller wrmiller at charter.net
Mon Jan 21 22:30:30 PST 2008


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Friends:

The recent thread on protecting PV wiring has inspired some creative 
thinking.   This is great.  I'd like to comment on one idea:  the glue on 
J-box:

Generally speaking, the application of glue in the field will always have 
variable results.  Instead, I suggest a bolt-on or clamp-on j-box.  This 
can clamp to the module frame or a mounting rail or rack.  I look forward 
to seeing a sketch or prototype.

In a way, our Volt-Guard wire shield is an after-market J-box.  We tossed 
the idea around for several days and spent a few hundred dollars at the 
metal supply making individual covers for individual modules until we 
realized we needed something to cover the entire back of one rack.  Cost 
was about $120.00 for the 12 gauge aluminum bent into a simple channel 
shape.  It is held on by 1/4X20 SS bolts.  The bolts go through the modules 
and then through Direct Power module hold-down brackets.  In quantities of 
10 the price gets much more reasonable, I recall less than $100 to protect 
wiring for 10 modules ($10.00 per module is realistic in our view).

If anyone wants more detail, I'll publish an engineering drawing.  (The one 
viewed on our web site is of modules for an Outback PS-1 system.  As such, 
the string quantity is 2.  So for 10 modules we ran 11 leads.  This 
necessitated 1" flex.  A battery-less installation would have 3 leads, 
allowing 1/2" flex.  The beauty of the Volt-Guard is that you can knock out 
the hole you need, where you need it.)

John Raynes, thanks for the compliment but this is one idea that is not 
appropriate for proprietary thinking.  This needs to get out there to 
inspire others to refine the concept and to demonstrate that safe practices 
are feasible and attainable.

William


-- _________________________________
William Miller
Miller Power and Communications
Voice :805-438-5600     Fax: 805-438-4607
email: wrmiller at mpandc.com
http://mpandc.com
License No. C-10-773985


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