[RE-wrenches] PVC

William Miller william at millersolar.com
Fri Oct 9 13:37:22 PDT 2009


August:

As discussed, PVC is sometimes the best solution in a corrosive 
environment.  I would never recommend supporting PVC as depicted in the 
photos.  Shooting a screw through comp roofing is questionable at 
best.  Better methods of installing PVC are available, including better 
straps and painting for UV protection.

I might add that although I would not tolerate brown PVC, UV browning does 
not render the conduit unusable.  The browning is only a few microns 
thick.  This is why the conduit says "UV resistant".

For hangers, I suggest a better anchoring system.  We use aluminum strut 
with stainless fasteners and hangers.  From our previous life as a tower 
rigging firm we have brought over stainless telecommunications 
hardware: 
http://awapps.commscope.com/catalog/andrew/product_details.aspx?id=13158 
This is available in various sizes

William Miller



At 11:26 AM 10/9/2009, you wrote:
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>All –
>
>PVC doesn’t hold up well in the Bay Area – Here’s a photo of  some ~4 year 
>old PVC browned PVC from Marin County:
>
>83877e5.jpg
>
>
>You can see that the straps melted resulting in the conduit sliding down. 
>Thank goodness we didn’t install this. PCV seems like a good option for 
>shaded areas.
>
>As Bill pointed out, if we use EMT we need to bond both ends of the 
>conduit to comply with NEC 250.97. My issue is that it is hard to find 
>outdoor rated bonding bushings – that’s why we’ve just been installing 
>cast metal boxes with threaded connections (complies with NEC 250.92(B)(2)).
>
>As William point out, EMT is robust and reliable. I still think that there 
>must be more efficient way to go between arrays. Maybe that’s why 
>commercial low profile racking systems are often fully integrated systems 
>with built in wire raceways.
>
>-August
>
>
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