Hvac power transitioning through roof

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  #1  
Old 03-18-19, 06:15 PM
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Hvac power transitioning through roof

So this is what the whip looks like coming out of the roof.

And a pic of it from below the roof. It looks like it enters 3/4 conduit.

The cable itself looks to be close to 3/4" thick. It two strands of coated aluminum wire and 1 ground wire, twisted aluminum. Feeding 30 amps. As it comes out of the flex line there is no outer casing, just the three wires.

Not sure how they transitioned from solid to flex conduit. If I pull on the flex line from above the conduit below moves up and down with it. I haven't looked inside the roof jack to see whats there.

Any suggestions on best practices to replace?
 
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Old 03-18-19, 06:26 PM
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Not an electrician, but I would probably use a standard Oatey plumbing roof boot flashing (with a rubber sleeve) just like a vent pipe penetration, but then instead of the vent pipe, use grey electrical pvc as a sleeve, with a couple elbows or sweeps on top so that the sleeve does a 180. Then your electrical whip can be snaked through it... and it's leakproof. You would just need to anchor the pvc to a 2x4 or something in the attic to keep it plumb.
 
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Old 03-18-19, 07:44 PM
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The cable should be sealed around metal cone which cover the top pipe penetrating the roof. The cone sort of floats over the pipe like an umbrella but is sealed solid to the cable.

Here is another option I found. The best description is an upside down P trap.

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Old 03-18-19, 07:45 PM
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Use one of these.
https://www.bestmaterials.com/detail.aspx?ID=17562&gclid=Cj0KCQjwg73kBRDVARIsAF-kEH-YAoUXRDhZl4TbdBgkBdOBqhgtnARwmOtCPSsHsXECI-J7lUhMYRoaApkFEALw_wcB
 
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Old 03-18-19, 08:04 PM
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I'm thinking you might be able to reuse the existing boot if it's weathertite to the deck..... especially since you said the flex/pvc slides in it. When you bring a flex out thru a boot like that it should make a sweep down and then up to your disconnect so that the water doesn't run down it.
 
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Old 03-18-19, 08:06 PM
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The existing doesn't look weather tight (to the conduit) at all. Also looks like it has almost rusted through.
 
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Old 03-18-19, 08:09 PM
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It's not an easy job to attach one of those to the deck properly.
What are you thinking..... cut it off just above the deck and install a new one or try to get it out ?
 
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Old 03-18-19, 09:41 PM
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Sorry, had to drive a hundred miles home....

I'm going to replace the roof jack as it's in such bad condition. So going off PCboss suggestion I found this

https://www.amazon.com/Oatey-flashin.../dp/B000IKOMY2

which is an option. This would ensure no water that gets under the roof jack can run down the outside of the conduit into the attic (or is this overkill?). Somehow they transitioned from solid conduit to flex conduit in a straightline under the roof jack (not sure how they did that in such a small space). I can't run just the cable to the DC as I'm sure it ends prior to entering the flex line and I don't believe local code or the individual wires are allowed to be outside. I would cover the Oatey boot with a metal roof jack to protect it.

I can screw in a 2X4 to secure below.

Using Xsleeper as an inspiration, what about running 1" solid conduit up through the roof jack connecting a LL Conduit Body



where it exits the roof jack and then connecting the liquid tite flex line to it (somehow?) ?
 
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Old 03-18-19, 09:53 PM
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A PVC LL or LB is not 100% watertight.
I've always used SealTite for an installation like that.
 
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Old 03-18-19, 10:09 PM
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A PVC LL or LB is not 100% watertight.
I've seen a lot of similar fittings outside buildings, is it because they are metal?

Is there a way to transition from the solid pvc to the sealtite (exterior box)? I'm leery of running sealtite down through the roof jack due to it's flexing and curvature.

Or could I run a long sweep as it exits the roof jack and then connect to the sealtite?
 
 

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