Are the Blocks used to support conduits that are run across a flat roof required to be secured to the roof ? I've seen several instances where conduits were strapped to 4x4 treated blocks that were just layed on the roof that had been kicked around and crooked.
Conduits on the Roof
- Thread starter jap
- Start date
- Status
- Location
- Massachusetts
That would be up to the AHJ to decide if the raceways are secured.
Where I am what you describe is common practice however I have started using these instead of wood.
http://www.erico.com/products.asp?folderID=189
on a side note, you might want to keep this in mind on rooftop installations:
Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable
(c) Conduits Exposed to Sunlight on Rooftops.Where conductors or cables are installed in conduits exposed to direct sunlight on or above rooftops, the adjustments shown in Table 310.15(B)(2)(c) shall be added to the outdoor temperature to determine the applicable ambient temperature for application of the correction factors in Table 310.16 and Table 310.18.
Table 310.15(B)(2)(a) Adjustment Factors for More Than Three Current-Carrying Conductors in a Raceway or Cable
(c) Conduits Exposed to Sunlight on Rooftops.Where conductors or cables are installed in conduits exposed to direct sunlight on or above rooftops, the adjustments shown in Table 310.15(B)(2)(c) shall be added to the outdoor temperature to determine the applicable ambient temperature for application of the correction factors in Table 310.16 and Table 310.18.
Thats good advice, but I dont have more than 3 Current Carrying conductors in this run.
- Location
- Massachusetts
K8MHZ
Senior Member
- Occupation
- Electrician
An AHJ on a roof? I think I have seen that exactly once in my life. :grin:
Come to TN. I'n not "scart" of ladders :grin:
- Location
- Simi Valley, CA
I'm with Steve on this one. I found about 10 corrections in an attic the other day and the guy straight up told me, "I didn't think you would go up there."
As for securing it to the roof, remember "securing and supporting", doesn't do any good to support it if you don't secure it. Now with some of the roof systems out there I would be very careful about what I did as they will void the warrenty if you do anything to the roof, but I have seen them install the blocks for the contractors.
Out here, any kind of wood turns to crap in a few years.
I started using short cut pieces of PVC and two hole straps. After everything is installed, I caulk the PVC pieces to the roof to hold it in place without doing any damage. When running across a roof, I always put supports on both sides of couplings and one in the center.
I started using short cut pieces of PVC and two hole straps. After everything is installed, I caulk the PVC pieces to the roof to hold it in place without doing any damage. When running across a roof, I always put supports on both sides of couplings and one in the center.
Volta
Senior Member
- Location
- Columbus, Ohio
Most conduits only need to be secured at the termination points xxx.30(A), and can simply be supported elsewhere xxx.30(B). That should make the various blocks ok for the long runs, but some extra means should be provided at the ends.
Karl H
Senior Member
- Location
- San Diego,CA
The "Sleeper's" I use are similar to Iwires but are heavy rubber,uni-strut on
top, and have slanted yellow lines on the sides. For the life of me I can't remember the name of the manufacture right now.
top, and have slanted yellow lines on the sides. For the life of me I can't remember the name of the manufacture right now.
Have you gone back on any jobs and the the state of the PVC to how well it's doing? I know you've seen baked PVC around here.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Here is a part of the installation instructions:
"
to compression at rated loads"
After reading that, I would say that securing them to the roof is not required.
"
▲
Once installed, CADDY PYRAMID will not creep due
to compression at rated loads"
After reading that, I would say that securing them to the roof is not required.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
I'm with Steve on this one. I found about 10 corrections in an attic the other day and the guy straight up told me, "I didn't think you would go up there."
So, in areas that inspectors may not get to means that following the codes in not applicable?
Those kind of comments always stoke my coals...if you get what I am saying.
Karl H
Senior Member
- Location
- San Diego,CA
I'm with Steve on this one. I found about 10 corrections in an attic the other day and the guy straight up told me, "I didn't think you would go up there."
As for securing it to the roof, remember "securing and supporting", doesn't do any good to support it if you don't secure it. Now with some of the roof systems out there I would be very careful about what I did as they will void the warrenty if you do anything to the roof, but I have seen them install the blocks for the contractors.
If a "Electrician" said that to me, I would have quickly pulled out the
"Fine-Toothed Comb!"
It certainly gets baked but it doesn't get brittle. I recently saw some that was installed 5 or 6 years ago and it was still in place.
The biggest prob;em is getting kicked around. On an old asphalt rolled roof the surface doen't lend itself to adhesion. The newer rubberized stuff will hold better but you are going to have to have to sweep off some of the dirt.
If money is no object, those nig curbs look like a pretty good way to go. For a simple circuit/service call I would probably just use what I stock.
macmikeman
Senior Member
- Location
- Planet macmikeman
They make treated 4x4 lumber, and they make lap cement. Some lap cement painted very liberally onto the bottom of the 4x4 (heck, I paint the whole support with it) and it stays put. Course here not much freezes to deal with so this might be a post only for sensible localities....
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