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PEX must be protected from UV A Florida bypass will require 20 feet of pipe be outdoors: it is in a rectangular tunnel, where it is mounted to concrete overhead, but sunlight illuminates the interior of the tunnel:

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The PEX bridges water from the left side of the 'tunnel' to the right side. The PEX pipe will be strapped to the ceiling of the open area above the vehicle in the photo

An older piece of PVC encases a CAT5 telephone cable and is showing signs of failure, presumably because of sunlight. What is the best practice to protect PEX from sunlight in this scenario?

gatorback
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1 Answers1

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You could use black polyethlene (non-pex) well-water pipe, which is inherently sunlight resistant. Also helps to keep your water from growing algae. Either as a sleeve or as the actual pipe for this section.

You could enclose it in metallic ducting, or PVC that was painted to protect it from UV, or PVC electrical conduit (sunlight-resistant as made, they claim.) I don't think painting the PEX is likely to work.

Ecnerwal
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  • I like the black polyethylene pipe sleeve idea. The water PEX would be 3/4. Perhaps it will fit in a 1" pipe. – gatorback Sep 19 '20 at 13:35
  • Will the PEX be inside the existing bridge or on the underside? If the latter , the deficiency with using tubing as a pipe chase is you cannot inspect the PEX should it develop a leak. For inspection you want a chase with removable cover. This could be insulated if you're in an area that freezes. Ideally the chase would exclude rodents. – Jim Stewart Sep 19 '20 at 19:23
  • @JimStewart. The latter: good insightful comments. – gatorback Sep 20 '20 at 00:58
  • For working on the PEX, should that ever be necessary, it would be best if the chase would consist of a flat side fixed to the structure and a removable cover. The cover would be a trough, rectangular or semi-circular. This design idea is used for the surface mounting of NM electrical cable and for the surface mounting of refrigerent lines of mini-split a/c systems. – Jim Stewart Sep 20 '20 at 09:58
  • Contraiwise - if the PEX ever leaked inside the "well pipe as chase" you'd **see** water leaking out the ends - and rather than "inspect it" or "work on it in the middle" you'd simply remove the whole section of PEX and replace it. Not that there's any particular reason it should leak in such a well-protected envrionment. But if, for some reason, it leaked, replacing the whole thing makes a lot more sense than patching it and waiting for the next leak to develop (since something was wrong for it to leak in the first place.) – Ecnerwal Sep 20 '20 at 14:35
  • A good type of chase might be the U-shaped ones that cable and internet providers use on the bottom part of electric power poles. They come in heavy galvanized steel and in plastic. The steel ones have mounting straps. The plastic ones I see have tabs for screws. – Jim Stewart Sep 20 '20 at 19:47