IPVMU Certified | 10/05/15 10:00pm
UV exposure is just one of several factors to consider. Freeze/thaw, high temp, rodent damage risk, and corrosion of conductor material are some others.
I live in South Central US in a pretty temperate region. Even then, laying UV rated cable on a typical roof is maybe good for 5 - 7 years before rotting out in spots.
1. What Brian said.
2. If you are pulling a permit check with the AHJ. In our area this would require IMC or better strapped to the building or on blocks.
I've generally used Schedule 80 for this. Practically speaking, I don't see why 40 wouldn't work, but an AHJ might have reasons.
The only other thing I've seen done is if you use real outdoor cable, shielded and (preferably) gel filled, and then use something like this. Not sure how much AHJs love it but I've seen it done many times. You could probably get away with it if the runs are short.
We use JM Eagle schedule 40/80 (They seem to last longer with UV Exposure) along with some rooftop pipe supports so that you are not just laying the pipe on the roof (roof supports Looks a bit more professional as well.)
These are very generic and basic and will more than likely fit most applications.
You can go for some more heavy duty supports, but that is dependent on the codes (if any), weather, and/or conditions for the application(s).
These are really nice, but a bit expensive.
Last thing you want is traffic damaging the wires! I would highly recommend that you protect the wires. If the customer does not want to pay the premium for the support, then, do not warrant the cable.
Good Luck and Aloha!
Looks interesting, but have never used.
Chesapeake & Midlantic | 10/07/15 01:32pm
When running cable over a flat roof, I always knocked drive rings into the parapet and used them to secure the cable, instead of just running across the shortest route. Don't want to be tripping a firefighter or something. No AHJ ever had a problem with it.
Norris, Inc., S. Portland, ME | 10/07/15 07:19pm
We generally use outdoor rated gel filled CAT5E (186 per 1000) and use PVC conduit and pressure treated cut 4 x 4 x 6 with C rings connecting the PVC located probably every 5-10' (our electricians know this distance). Use a chop saw onsite to cutup the 4 x 4 x 8' posts. Cheap and effective.
Never lay it directly on the roof.
IPVMU Certified | 10/08/15 03:40am
I have always installed conduit for cables on roof tops, never laid it on the roof. Not to say that I have never seen cables laid out on roof tops, typically it is satellite installers or IT doing a Pt2Pt. As you state conduit will add a good amount of money however it will protect your customers investment, reduce system tampering and minimize callbacks due to damaged cable. As many have pointed out there are quite a number of products to use if you are going to install conduit along the roof top rather than on the parapet.
Great Find! I like clean professional installations. I can already see other contractors using unused pipe saddles. Indeed, very interesting; something else to add to my arsnel of installation solutions!