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Discussion Starter · #1 ·
Hi Guys,


Maybe someone has run into this before.


We are trying to feed some cables through pre-installed pvc 1/2" tubes that go from the attic where my theater will be to the panel box. It seems that there are 4 elbows in the tubes.


We have been trying with metal wire to push through the tube but it seems that something is obstructing the passage. The only thing we can think of is that it might be concrete.


We put vegtable oil down the tube and it did come out in the panel box. We also tried blowing air and it came out the other end without much trouble, so the path is certainly not completely blocked.


Does anyway have any suggestions as to what to do in this case? My walls are all concrete and the tubes are within the concrete.


Thanks in advance,


Nick
 

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Did you use the long sweeping electrical elbows or the 90s for plumbing?


Take a shopping bag and attach it to a string. Insert it in the tube. At the other end use a shop vac to suck it through the tube. Now use the string to pull the cable through the tube.
 

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Discussion Starter · #3 ·
Thanks for your reply.


Not sure what the builder used. In the attic they used long sweeping elbows but i'm not sure whats actually buried in the concrete. I'll try the shopping bag method.


I need to buy a shop vac anyway.
 

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I would tear a piece of the shopping bag, don't know if a shopping bag will fit through a 1/2" with tight bends.

Quote:
Originally Posted by In2Photos /forum/post/18166928


Did you use the long sweeping electrical elbows or the 90s for plumbing?


Take a shopping bag and attach it to a string. Insert it in the tube. At the other end use a shop vac to suck it through the tube. Now use the string to pull the cable through the tube.
 

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Discussion Starter · #5 ·
Ok i'll give it a shot on Monday.


If that doesn't work (meaning it sucks it down but not through... What is the next step. I have read around that since we will use the tube for power we could use muriatic acid to slowly dissolve the concrete. I think this is really the best 'alternative' solution. We did buy a much thicker gauge feeding wire today to see if we can use it to push through but we will find out on Monday.


First option will be the thicker feed wire


Second option will be the shopping bag and string


Third option will be muriatic acid


Fourth option break the wall where it's getting stuck.
 

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I had the same problem with PVC between basement and attic. The pvc was a hard 90 bend. the fish tape felt like it was hitting something hard, but it was just the bend. Blowing a string through, fixed my problem.


Once you get one through, tie a few more onto that one and leave them in place for future needs.
 

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Are you using wire or a snake to push through the tube; if you can get your hands on a snake it should work better than a wire; unless there is a tight bend in the tubing. If the snake don't work before you go and buy a shop vac use the home vac to see if you can feel a vacuum with it hook to one end of the tube; if you can't feel a vacuum or the suction is is low then there maybe a blockage in the pipe. If your home vac has enough suction when you hook it up to one end of the tubing and turn it on you may hear a high pitch whistle this is a good sign and you mybe able to use the home vac to suck the string through.
 

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you cant feed wire (i'm assuming solid copper when you say "hard wire") through more then 1 90 degree. it just wont ever work.


you must use a fish tape (spring steel, that you can rotate and change direction of bend to get through as many 90's as you want) OR the vacuum cleaner method.


just fyi, 3 90's is about the most you can pull through, depending on conduit size and since 1/2 is tiny, dont expect this to be an easy job at all. you are talking about a MASSIVE amount of surface area of the wire in conctact with the pipe due to the 90's, the friction is really amazing.
 

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once you get your pull string make sure you have lots of lube on the wire, they make wire lube just for this kind of thing, it will help make the wire go through otherwise it will take forever.
 
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