Conduit Blockage

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  #1  
Old 08-13-07, 07:48 PM
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Conduit Blockage

We recently completed a new house which has a basement with poured concrete walls. Inside those walls are several runs of 3/4" PVC type conduit. Most of the conduit is fine but I've run into 2 or 3 spots with some kind of blockage. I've pulled all the wire by vacuuming a line through the conduit and pulling the wire back through but in these spots, either the line won't get through in the first place or when I pull the wire back through it eventually hangs up and breaks my line.

Is there some kind of "trick of the trade" for clearing out these blockages? I can't tell if they're concrete that leaked through somehow or something else. Is there anything I can try?
 
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Old 08-13-07, 08:34 PM
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try pouring a 2 liter of coca-cola into the pipe and let it sit overnight, then blow it out with water, the cola will eat the concrete. Also, you might try muratic acid, it eats concrete, but not plastic, or pvc.
 
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Old 08-13-07, 08:39 PM
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Or the concrete collapsed the conduit.
 
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Old 08-13-07, 08:50 PM
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I am thinking that the walls were shotcreted and the conduits weren't taped at the top...
 
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Old 08-13-07, 09:42 PM
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Never lived in a part of the US that has basements so was thinking poured when I suggested collapsed. Have seen that happen to 1-1/2" PVC DVW under concrete slabs here.
 
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Old 08-14-07, 06:44 AM
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Originally Posted by hbsparky View Post
I am thinking that the walls were shotcreted and the conduits weren't taped at the top...
They were just poured... no shotcrete. I do remember we capped all of them at the top. I guess there's always a possibility that one was missed but doubtful.
 
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Old 08-14-07, 06:47 AM
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Originally Posted by ray2047 View Post
Never lived in a part of the US that has basements so was thinking poured when I suggested collapsed. Have seen that happen to 1-1/2" PVC DVW under concrete slabs here.

no, you're right. They were poured. The walls are 14' tall and 14" thick in some spots so I guess there's a lot of pressure that goes along with that. What do you do if that happens? Is there some kind of bit that can drill it out or are you just out of luck?
 
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Old 08-14-07, 06:59 AM
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Originally Posted by hbsparky View Post
try pouring a 2 liter of coca-cola into the pipe and let it sit overnight, then blow it out with water, the cola will eat the concrete. Also, you might try muratic acid, it eats concrete, but not plastic, or pvc.
Now that's the kind of tip I was looking for. I wonder if that only works if the conduit is completely blocked? In other words, will it contact the concrete enough if it's only partially blocked and won't hold the acid in one spot?
 
  #9  
Old 08-14-07, 08:46 AM
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Metamucial will clear out the blockage, it reacts the same way as cola but is gentler to sensitive pieces, such as conduit.
 
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