I have to run a circuit to supply power to a sign across about 50 feet of flat roof. In the past I've put down 1 foot long pieces of treated 2X4 every 5 feet and ran PVC conduit. But this time I would like to do a neater job. I cannot run it on the side of a parapet. Can I run it on top?Or perhaps I should run EMT with compression fittings. Any ideas out there? Thanks Bob
EMT will meet code but IMO has no place outside on a roof, the weather conditions in MA make EMT rust out and fall apart (especially in the small sizes) long before the equipment you feed with it. If it gets kicked around on the roof the compression couplings sometimes fall apart.
Try IMC, it sounds like you will be running 1/2" so a 3/4" EMT bender will bend it easily, if you do not have a threader, with some planning you can use very few compression connectors.
I would use emt w/raintight fittings or possibly IMC , if there is heavy maintance taffic on this roof. The sun warps pvc bad and makes your job look really terrible after a couple of months. Also some strut on the p/t 2x4 ,would be o.k., and look good.
Shoot first, apologize later.....maybe
Re: Conduit on flat roofs#22926 03/07/0308:35 AM03/07/0308:35 AM
They're a Caddy (Erico) "Pipe Pier", and they work very well, but they're quite expensive per unit...S PS EVAD, good thing you put in a ground wire, as you must know how they get busted up! (and probably not put in tight in the first place)
[This message has been edited by electure (edited 03-07-2003).]
Re: Conduit on flat roofs#22929 03/08/0301:39 AM03/08/0301:39 AM
I ended up running 3/4 inch EMT. I supported it on 10 inch lengths of treated 4X4 every 5 feet. I gooped the wood to the roof and secured the EMT to the wood with one hole straps. I used compression type couplings and TA's. I'm tempted to spray the compression fittings and the straps with zinc to seal them and prevent future rust. Is this overkill? The sign contractor wanted 3-20 namp circuits and he wanted me to run #10 wire since it was over 50 feet from the panel. I ran 5#10's (black, red, blue, white and green) from the 120/208 volt 3 phase panel. I installed a 3 phase 20 amp breaker in the panel. On the roof I installed a 3 phase main lug panel with 3 single phase breakers. I also installed a GFCI fed by a seperate breaker on phase A. Have any of you installed a flood light for repairman's convience? Where I penetrated the tarred roof I gooped it wirth mastic. I told the customer to have his roofing contractor check it. That's about it. bob
Re: Conduit on flat roofs#22930 03/08/0310:19 AM03/08/0310:19 AM
probably okay to use tar to stick down your sleepers on a tar roof. But I've seen this done on EPDM (rubber membrane) several times. Tar will disolve the rubber so be careful what type of roof you're on.
Re: Conduit on flat roofs#22931 03/08/0303:50 PM03/08/0303:50 PM
Here's a good product. Portable Pipe Hangers They may be on the expensive side, but they work really well. I had a job that these were "spec'd". Look at the PP10. I think it would have worked well for you, elebob. Click on the "products", and then click the "view our entire product line" on the bottom right corner.
[This message has been edited by The Watt Doctor (edited 03-08-2003).]
The Watt Doctor Altura Cogen Channelview, TX
Re: Conduit on flat roofs#22932 03/08/0309:20 PM03/08/0309:20 PM
Bob, Just a thought, but, over here we sometimes use what we call "Conduit Clips", they are made from PVC and they hold the conduit up off of the surface. Not sure if they are available in the US, but if you visit www.clipsal.com.au you will see what I am on about, they are under Product Code 280. They're really easy to fix, too!. Hope this helps.
[This message has been edited by Trumpy (edited 03-08-2003).]