roof details [RE-wrenches]

[Jeff Clearwater]

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Hi William,

Nice detail on the roof penetrations. And that looks like quite an 
adjustable rack system - is that what I'm looking at?  Nice work. 
What climate is this?  And yes posting web sites for comparison is 
great!

One slight improvement suggestion would be to use EMT instead of PVC 
for that section exposed to the sun that runs along the roof before 
going down.  Especially if in a climate with hot sun and ice build-up 
in the winter like we have in New England or in the mountains in the 
Sierras.  The sun makes the PVC brittle over the years (and ugly) and 
the ice damming pushes it around - I'd go with EMT there.

Perhaps something you want to think about Peter.

Best,

Jeff


>Peter:
>
>If you'd rather not penetrate a roof with conduit, then you will be 
>forced to run conduit greater distances over roofs.  I can not see 
>myself running conduit to and over an eave and I can't see myself 
>penetrating a roof and an eave to come down an exterior wall.  We 
>connect our EMT to either the rack foot where it is lagged onto comp 
>shingles or, in the case of any type of tile, to the strut that we 
>use to mount our racks.  No conduit clamps are glued to roofing.
>
>To illustrate this, I put up two pictures on my Web site:
>
>-The first photos is: 
><http://www.mpandc.com/case_studies/Metal_to_PVC_Conduit_on_faux_slate.jpg>Metal_to_PVC_Conduit_on_faux_slate 
>.  That is EMT coming through the roof and then we convert to PVC 
>for corrosion resistance.  The posts are the DPW Power Posts, the 
>strut is stainless (splices on back order).  The roofing is the faux 
>slate (it is light, rugged and skid resistant).
>
>-The second photo is: 
><http://www.mpandc.com/case_studies/Then_the%20racks_and_modules.jpg>Then_the 
>racks_and modules  This shows the racks tilted up, some loaded and 
>two tilted back down.  No quick connects were used in the making of 
>this PV system.
>
>I have never used the system that uses threaded rod through tile. 
>Sounds a little weak to me.
>
>I hope the photos help explain the concepts.  I'm new to this web 
>authoring thing.  I'd appreciate any feed back on it's effectiveness 
>as a medium of exchange between colleagues.
>
>William Miller
>
>
>
>
>
>
>
>
>
>At 07:05 PM 2/3/2006, you wrote:
>
>>William,
>>I'd love to see your wrap on how to handle jb's on tile roofs and conduiting
>>of multiple DC strings over slab or s-tile, IF there's a different or best
>>way to approach each.  I'd also like to know more about what adhesives are
>>being used out there, IF used, or recommended practice for rooftop jb's with
>>conduiting on flat cement slab tile type rooftops, where I would think it
>>possible for a good strong adhesion that can survive blazing surface heat.
>>Even with someone tripping over or just a stressed conduit entry into a hot
>>rooftop jb, is there an adhesive out there that works for 25 years in
>>advanced life tests and will keep the jb in place, cold and hot, cold and
>>hot for years?
>
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-- 
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design Associates
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com

530-470-9166
877-SOLARVillage
877-765-2784
425 Nimrod St.
Nevada City, CA 95959
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~

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