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Using a "wet" conduit under patio to telescope mount

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#26 Tom K

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Posted 19 November 2019 - 09:44 AM

That conduit in the concrete appears in the image to be so far out of round that unless you chip away the concrete you would have a real hard time getting anything round to go into it that is the same nominal size.   While I still think that the best solution is to chip away the concrete to a sufficient depth to be able to get the conduit back to round, if you are set against that concept and want to insert something you will probably need to go a size or even two smaller so that it will even fit into the conduit.  

 

I still recommend pulling rags through to get the water out - with a larger diameter line it would take a very large amount of air to move it out with a compressor - something that a small compressor just would not do.  Run a fish tape through, put in some pulling line, and then pull rags back and forth until dry enough.

 

You can then pull your wires, and then put them through the smaller diameter slab side conduit before sealing it in.   Again, while this would not be my first choice, if you got some robust construction sealant you might be able to seal the annualar space between the conduits.   At that point, I would get some concrete mortar from Home Depot/Lowes and mix up a dry-ish back and do what we would call a dry pack.   You should hand form a raised area around the now protruding conduit so that water drains away from the area.   I would do a conical shaped pack probably 6" in diameter and a few inches high.   This will deflect water away from the area that you just sealed.   Note that if the hole is in a low spot itself you will have challenges with this as the bond between the mortar and the slab is not water tight itself.

 

This unreinforced mortar will degrade over freeze thaw cycles and may need to be replaced periodically.

 

Just my $0.02.



#27 John Fitzgerald

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Posted 19 November 2019 - 10:39 AM

I would chip it out, splice it, and mortar back around the chipped area.  Pull rags through to dry it.   A stiff wire will work in lieu of a fish tape.



#28 D.T.

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Posted 19 November 2019 - 03:39 PM

That conduit in the concrete appears in the image to be so far out of round that unless you chip away the concrete you would have a real hard time getting anything round to go into it that is the same nominal size.   While I still think that the best solution is to chip away the concrete to a sufficient depth to be able to get the conduit back to round, if you are set against that concept and want to insert something you will probably need to go a size or even two smaller so that it will even fit into the conduit.  

 

I still recommend pulling rags through to get the water out - with a larger diameter line it would take a very large amount of air to move it out with a compressor - something that a small compressor just would not do.  Run a fish tape through, put in some pulling line, and then pull rags back and forth until dry enough.

 

You can then pull your wires, and then put them through the smaller diameter slab side conduit before sealing it in.   Again, while this would not be my first choice, if you got some robust construction sealant you might be able to seal the annualar space between the conduits.   At that point, I would get some concrete mortar from Home Depot/Lowes and mix up a dry-ish back and do what we would call a dry pack.   You should hand form a raised area around the now protruding conduit so that water drains away from the area.   I would do a conical shaped pack probably 6" in diameter and a few inches high.   This will deflect water away from the area that you just sealed.   Note that if the hole is in a low spot itself you will have challenges with this as the bond between the mortar and the slab is not water tight itself.

 

This unreinforced mortar will degrade over freeze thaw cycles and may need to be replaced periodically.

 

Just my $0.02.

No, the conduit is round.  I had neglected to remove some tape on the end of the tube.  I have attached an updated photo.

Attached Thumbnails

  • DSC04504.jpg

Edited by D.T., 19 November 2019 - 05:50 PM.


#29 Tom K

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Posted 20 November 2019 - 08:08 AM

OK if it is round I bet this will work.   Since you have a 1.5" conduit, the ID of the conduit should be about 1.59".   The OD of a 1.25" conduit is 1.66".   You could get a piece of 1.25" conduit and sand down the OD on one end by 7/100ths of an inch to get it to slide into the 1.5" conduit.   You may want to shave off a little more to give space for the glue, so let's say 1/10th of an inch.   If you have access to a lathe it is even easier.

 

However you get there, just create an end of the 1.25" conduit that will fit into the ID of the 1.5" conduit and glue it in there.   Then vacuum, blow, and swab out the water and install your weatherproof boxes - done!   You could even get all the water out first, pull your wires, and then glue in the 1.25" adapter you just made.

 

That is what I would do.   Good luck!



#30 John Fitzgerald

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Posted 20 November 2019 - 08:57 AM

The id and od of most pvc conduit varies a little.  A tight slip fit with glue on it and a mallet to seat it works best.  I would swab it dry with rags.  Forget blowing it out.


Edited by John Fitzgerald, 20 November 2019 - 08:58 AM.

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#31 greenstars3

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Posted 21 November 2019 - 04:56 AM

With the short run you have and the fact that you don't know if the water will come back in due to faulty glue up you could try to get as much water out as you can and then snake a 1 inch flex water proof conduit thru the 1 1/2 inch you already have  and pull your wires thru it to make sure that you have no problems in the future. Your underground direct burial rated wiring that you spoke about will also be fine in the waterlogged conduit. But if you need dry wires for the computer the coated flex conduit would work and you could terminate it with junction boxes on both ends without chipping out the concrete, and both the 10 gauge direct burial and the USB wires should fit thru the flex armored conduit.

 

Robert    

 

edit: unless you intend to also run some 120 volt AC you should not have to worry about flux, you should ask an electrician about the max fill and derating if you need to pull a lot of wiring thru this 1 1/2 anyway   


Edited by greenstars3, 21 November 2019 - 05:02 AM.


#32 greenstars3

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Posted 21 November 2019 - 04:43 PM

On further reflection.

 

When you do a washed rock finish in a cement surface you use a lot of water to wash off the top layer of cement, just a guess but I bet that is where most of that water came from, unless you have really high ground water, if you dry the conduit out you should be fine and need not worry about it. So my first post about this issue does not apply, also the long radius conduit 90 in one of the photos will make pulling the wires easy and the contractor did not fubar your conduit, he just washed off the top of the concrete for a cool washed rock look, and I hope that the top of  the conduit at patio level was sealed while he washed the surface, also if you have calipers check to see if the conduit is 1 1/2 or 1 1/4 inch. The flared  end may be what you are looking at on the surface of the patio and a short stub may just glue right in.

 

Robert   

 

edit: some of the curved radiuses in conduit are already flared to except the next joint of pipe  


Edited by greenstars3, 21 November 2019 - 06:12 PM.


#33 BeltofOrion

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Posted 21 November 2019 - 11:01 PM

"Too bad the contractor didn't leave an inch as a lip.  The other end is an upturned pipe which is beneath a shelter.  That end, should be good enough just to wrap it with water resistant tape.  Near the pier, I am now thinking that I can slide a 1.5" O.D. metal tube into the conduit such that a couple of inches project above the patio surface.  Then I can caulk the edge around the metal tube at the patio level."

 

That  conduit looks like PVC pipe. So, on the pier end why not use some PVC cement and attach a right angle fitting to it. Although, I must say, it looks like it got squished out of shape somehow ... oval now rather than circular.

 

Whoops ... didn't read page 2. Guess it isn't oval. Also, I didn't see Tom K's suggestion before I wrote this post.


Edited by BeltofOrion, 21 November 2019 - 11:04 PM.


#34 John Fitzgerald

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Posted 22 November 2019 - 12:54 AM

I hope the contractor did not wash mortar in and stop up the conduit.   Have you pushed anything through it yet?  That looks like the bell end of a 90 degree sweep ell sticking up to the edge.  As was said two posts up, you could glue a piece of pipe right into that. 



#35 airbleeder

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Posted 22 November 2019 - 10:58 AM

   The contractor may have left the conduit flush with the concrete to avoid a possible tripping hazard. Dry it ever how you choose, temporarily plug both ends until you run the wires then seal it up with an outdoor caulk.

   I don't see the problem others have expressed. I think we tend to make things overly complicated and needlessly worry about a problem that isn't there. If it were my patio, that's what I would do.



#36 MikeBY

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Posted 23 November 2019 - 07:12 AM

Check the power requirement for the USB extender. The one you linked looks like it requires 5vdc at both ends. Also, if you are planning a USB hub at the scope, check its power requirement and if USB powered, verify the receiver of your extender can supply power to plugged in devices. Things like USB power that we take for granted don't always work the same way over extenders that change media types. It might be fine once as in this case a 5vdc source is connected to the receiver, but its best to check.




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