[RE-wrenches] Rooftop wiring methods between multiple subarrays

R Ray Walters ray at solarray.com
Sat Oct 10 10:20:27 PDT 2009


I deal with New Mexico/ Colorado/ Texas for my inland experience, and  
Hawaii/ Mexico for my coastal experience.
Hawaii is hard core enough that many main service boxes are Stainless.
New Mexico requires the wet loc fittings for EMT with the integrated  
plastic seals. We use our old stock of regular compression fittings  
indoors now.
I want to try the Polyetheylene conduit system, but I've never  
actually seen it used. It is listed in the NEC though, and has a much  
lower coefficient of expansion.
I don't know how it will perform relative to UV, though. The black PE  
plumbing pipe I've used holds up very well to UV, just never tried the  
electrical version.
I'm not even sure what fittings you would use with it.
Anybody have experience?

R. Walters
ray at solarray.com
Solar Engineer




On Oct 10, 2009, at 10:33 AM, August Goers wrote:

> Hi Ray –
>
> What coastal region or regions are you familiar with? I’m really  
> only familiar with the San Francisco Bay Area but thoroughly painted  
> EMT seems to hold up through the long haul even just a few blocks  
> from the ocean. If it isn’t painted the straps and fittings start  
> rusting in less than a year. I imagine that warmer and more tropical  
> coastal regions would indeed rot EMT out in no time.
>
> As a separate note, San Francisco now requires the use of fittings  
> listed for use in wet locations. These “wet loc” fittings we’ve been  
> using for the last few years seem to hold up quite well.
>
> -August
>
> From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches- 
> bounces at lists.re-wrenches.org] On Behalf Of R Ray Walters
> Sent: Friday, October 09, 2009 4:22 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Rooftop wiring methods between multiple  
> subarrays
>
> EMT needs to be "pickled"  with vinegar or acid, to get the paint to  
> hold. I love it for inland work, but near the ocean, it'll rust  
> through in 5 years. I'm not sure how much more time paint would buy  
> you.
> Anybody use other plastic materials HDPE? Supposed to not have the  
> expansion problems of PVC.
>
>
> R. Walters
> ray at solarray.com
> Solar Engineer
>
>
>
> If you have to run around the roof with EMT, you can protect it from  
> rust
> with a coat of paint.
>
> Regards,
> -Hans
>
>
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