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I'm setting up my entrance riser for my shop. The weather head is 13' up from the top of the panel box, and the shop "roof" is 11' from that with 2' of the 2.5" IMC conduit riser extending above the roof. The problem is, the IMC comes in 10' threaded sections so I will have the connection about 1' below the roof line. The connections are very rigid, and I will put a single brace above the connection to the wall (see picture) I cant find anywhere in code showing this other than an implication that there has to be a brace between the connection and the unsupported section. The threaded connections seem as rigid as the pipe itself.

My question is: Does this attachment meet NEC intent?

The second option which I don't like and don't have the equipment for, is to cut the lower IMC piece and re-thread it at about 8' length... For info, I am in AZ and the service will be Tucson Electric Power.

enter image description here

Final set up: (i ended up threading the 5' section at a local machine shop) enter image description hereenter image description here

mark f
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    If (and they may not be) both pieces are threaded now, just flip the whole assembly so the short bit is what connects to the box. Presumably you can take the conduit to someone and get threads cut if the short bit is not threaded at one end. – Ecnerwal Oct 12 '20 at 17:16
  • True, I'm trying to avoid having to cut threads if i can. Its just an extra step which I will have to shop out to someone. Ace used to have thread cutting apparatus at most of their stores, but I think most locations have abandoned the lathes or they have broken over time and not been repaired. – mark f Oct 12 '20 at 17:23

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Some great suggestions and I did get a shorter 5' piece of the 2 1/2" IMC threaded and did exactly what Freeman and Ecnerwal suggested. But to answer my original question:

Answer: The final top section of IMC conduit needs to be securely tied to the structure by at least one strap/tie. (This is from my interpretation of my local codes and discussions with the TEP installation engineer) This means the coupler will need to be (at least) ~6" below the top depending on the wall makeup you will be tying to. (more is better). And that a second strap/tie will need to be BELOW the top coupler more than 8" (from the TEP SR guidance). So from what I've found and interpreted, I Could have set it up like my original cartoon, but the recommended way was superior and had a stronger finished "appearance". This is my interpretation from my local electric company service requirements: https://esr.tep.com/wp-content/uploads/SR-305.pdf

mark f
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Why not simply flip the riser upside down, so the 3' section goes directly into the meter/main, and the 10' piece goes up through the roof into the weather head. That way you can easily get two clamps between the coupler and the roof line, securely holding the 10' piece, and 1 clamp on the 3' piece between the coupling and the panel.

FreeMan
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  • The 3' shorter top section will be threaded on the end with the connection and clean cut on the end that slips into the weatherhead. The HUB on the panel side requires a threaded fit; so this option would also require me to thread the short section. Each 10' piece of IMC comes with about 4" of thread cut into each end. – mark f Oct 12 '20 at 17:20
  • Fair enough, @markf. It seems inherently more stable with it "upside down" (from your current design), and I understand your question. I'd be willing to be that any local electrician or machine shop would be able & willing to cut the threads for you. I do understand that it's an extra step and the travel/time cost may be greater than the out of pocket cash for the physical labor... – FreeMan Oct 12 '20 at 17:27
  • I concur that from the sketch it would appear more stable with the short piece on the bottom, but those screw on IMC 'splice' connections are super beefy. Im just wondering if I am making a mistake by setting it up as in the pic, and my inspector or TEP might have issue with it based on 2017 Code. Guess I should just find a place to have threads cut and know it will pass... – mark f Oct 12 '20 at 17:31
  • Called 15 places locally. plumbing, electrical, granger, HD, Lowes, Ace... apparently everyone else who is using 2 1/2" hard conduit has the ability themselves to cut threads :I – mark f Oct 12 '20 at 23:29
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    @markf try a machine shop? Make a new toy pur... er... tool purchase? – FreeMan Oct 13 '20 at 10:21