[RE-wrenches] Rooftop wiring methods between multiple subarrays

[August Goers]

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:

[cid:image002.jpg at 01CA48DF.F8EAE150]

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


August Goers

Luminalt Energy Corporation
O: 415.564.7652
M: 415.559.1525
F: 650.244.9167
august at luminalt.com

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William Miller
Sent: Friday, October 09, 2009 12:07 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Rooftop wiring methods between multiple subarrays

Ray:

Good question.  We do use PVC in coastal zones to avoid corrosion.  We try to keep it in the shade, paint it where exposed to UV and support it in close intervals.

William


At 10:57 AM 10/9/2009, you wrote:

Except for coastal installations.... where  EMT is NOT  recommended outdoors, PVC browns out and warps, and we should therefore use product X???

R. Walters
ray at solarray.com<mailto:ray at solarray.com>
Solar Engineer




On Oct 9, 2009, at 11:38 AM, William Miller wrote:


August:

I suggest the use of EMT with proper fittings to protect high voltage, high amperage DC Wiring on rooftops.  Sure it is time consuming, but high quality, reliable craftsmanship will always be thus.

William Miller



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