How To Strap PVC Conduit To 6" Diameter Steel Pole? - Electrical - DIY Chatroom Home Improvement Forum
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Old 08-21-2015, 01:28 PM   #1
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how to strap PVC conduit to 6" diameter steel pole?


I'm a homeowner doing my own new construction electrical/solar in Custer County, CO (which allows homeowners to act "as-if" they were licensed electricians of they are working on their own homes). I had my rough-in inspection for the solar part yesterday. Basically, I passed with flying colors. The only minor thing he dinged me for was how I had the PVC conduit strapped to the side of the metal poles that my arrays are mounted on.

Background: my 9 panels are mounted on 2 poles (6 panels on 1 pole, 3 on the other ~20 ft away), with the combiner box mounted to the pole that has 6 panels of the poles. I've run the conductors from the 3 panels on the other pole into PVC conduit down the side of the pole, then underground in a trench to the base of other pole, then in PVC conduit up the 1st pole and into the combiner box. I used zip-ties to strap the conduit to the poles and the inspector said this was unacceptable (which I kind of agree with, but didn't know how else to do it).

The inspection report reads "Use approved conduit supports on conduits for solar array - Mineralac, unistrut or equal." I did a web search for the Minerallac supports and found their 3S hanger. But the steel poles are 6" diameter and with walls about 5/8" thick and using the Minerallac hanger would require me to drill holes in the steel pole and then put threads in the hole with a tap/die set, etc. and I currently have no way of doing that (i.e., don't own a tap/die set that is sharp/strong enough to thread this steel pole).

What other means of strapping the conduit to the side of the poles would be "Approved or equal"? For instance, could I use big band straps (which is how I attached the combiner box to the pole)?

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Old 08-21-2015, 02:38 PM   #2
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If you could find some slotted u shaped metal plates with a 1/4" x 20 threaded hole, you could strap them to the posts with worm-gear clamps then bolt the appropriate size minerallac into the hole of the plate.

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Old 08-21-2015, 02:53 PM   #3
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Quote:
If you could find some slotted u shaped metal plates with a 1/4" x 20 threaded hole, you could strap them to the posts with worm-gear clamps then bolt the appropriate size minerallac into the hole of the plate.
I don't quite understand what you're suggesting. What do you mean by "slotted u shaped metal plate"? And by "worm-gear clamps" do you mean the same thing I mean by "band strap" (i.e., a BIG hose clamp)?

The way I attached the combiner box was to drill a hole in a band strap and ran a bolt through the mounting hole in the combiner box through that and then attached the band strap to the pole.

So, could I do the same thing by attaching the Minerallac hanger to a band strap and then the band strap to the pole?
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Old 08-21-2015, 03:23 PM   #4
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Something similar to this using large hose clamps or band straps if you wish. how to strap PVC conduit to 6" diameter steel pole?-image.jpg
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Old 08-21-2015, 03:25 PM   #5
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Quote:
Originally Posted by pbiron View Post
I don't quite understand what you're suggesting. What do you mean by "slotted u shaped metal plate"? And by "worm-gear clamps" do you mean the same thing I mean by "band strap" (i.e., a BIG hose clamp)?

The way I attached the combiner box was to drill a hole in a band strap and ran a bolt through the mounting hole in the combiner box through that and then attached the band strap to the pole.

So, could I do the same thing by attaching the Minerallac hanger to a band strap and then the band strap to the pole?
If I understand your idea correctly, the minerallac would be 90 degrees in the wrong direction.
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Old 08-21-2015, 03:26 PM   #6
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What I do with stuff like this is drill a pilot hole smaller than the screw I want to use. Then I use a bit the same size as the screw but stop about 1/8" shy of clearing through. Then attach strap with the screw.
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Old 08-21-2015, 03:47 PM   #7
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I just spoke with the guy I bought all my solar equipment from (including the steel poles), who is also a licensed solar installer, and he told me, that:

1. the walls of the pole are only 1/4" thick
2. he just drills a hole in the pole and uses a self-tapping machine screw to attach the Minerallac hanger to the pole (with the drilled hole slightly smaller than the machine screw)

I guess the steel is not as strong as I think it is.

I'll give it a try tomorrow (assuming I can find the Minerallac hangers at my local hardware store this afternoon) and report back on how it works.
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Old 08-24-2015, 09:02 AM   #8
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Success! The steel in the poles really wasn't as hard as I thought it would be. Although I did have to use my corded hammer drill to drill the holes, my battery powered drill wasn't powerful enough.

Attached are a couple of photos, including one showing a closeup of the Minerallac hangers and the 1/4" x 1" machine screws I used to attach the hangers to the pole (notice my little Honda generator in the background...I've got about another 2 hours worth of work connecting all the conductors/etc into the interver and then I shouldn't have to use that puppy onsite any more!!).
Attached Thumbnails
how to strap PVC conduit to 6" diameter steel pole?-drilling.jpg   how to strap PVC conduit to 6" diameter steel pole?-machinescrew.jpg   how to strap PVC conduit to 6" diameter steel pole?-finished.jpg  

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