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I need to replace a sump pump, but have run into a problem. The route for the cord goes through a 2" pipe with two 90 degree bends, and fish tape is ineffective. The pipe appears poorly jointed as well and uneven. Is there a way to get the cord through this convoluted pipe?

The old cord is already out of the pipe, and cannot be used to drag a pull string.

Getting a power cord through a pipe with many turns without fish tape

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    I once managed this by shoving a cheap metal tape measure through a pipe like that. The tape wants to stay straight but will buckle neatly at the bends and continue on it's way, then pull it back through with a cord attached. – Wossname Oct 2 '16 at 9:41
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    I wonder if a sewer snake might work better. – Hot Licks Oct 3 '16 at 1:38
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    I don't have any wiring to do, but the answers seem so fun that I could try them anyway... – algiogia Oct 4 '16 at 10:50
  • @HotLicks I tried a sewer snake. No possible way. In fact even that cord end in the picture would not go through WITH a pull string, until I pulled another trick or two. -OP – Bryce Oct 4 '16 at 15:09
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This technique worked great. I tied a string to the cord, tied a plastic bag to the string, and sucked that bag right through the pipe using a vacuum cleaner.

plastic bag as fish tape alternative

Just be a little cautious: the bag can travel through the pipe in a blink of an eye, and you might not want to have to fish the bag out of the vacuum.

Once the bag is through, pull the cord through, and untie the string.

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    Electricians have small foam plugs called "mice" that they use for this -- probably easier to work with than a plastic grocery bag. – ThreePhaseEel Oct 2 '16 at 1:24
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    You can solve the problem of sucking the bad by using some sort of mesh at the end. Air-confitioner filters could work great with this. Also, for situations where the vacuum cleaner tube is too small, you can use a paper sheet with a hole smaller than the vacuum cleaner's tube diameter. – Ismael Miguel Oct 2 '16 at 11:41
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    Or just duct-tape 2 pieces of rope in 'X' fashion to tube's exit if you don't have a mesh on hand. – Daerdemandt Oct 3 '16 at 9:43
  • I've made a bullet to do this using the tapered part of a marker pen. A light ball (ping pong ball or smaller hollow ball from a toy) also works well. You can get more suction by removing fine filters from the vacuum, but keep something to protect the motor. There is an upper limit to the bends you can get round this way -- if it starts to resemble a coil, the fish string will pull tight. – Chris H Oct 3 '16 at 13:02
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    @ThreePhaseEel foam plugs have their place I suppose, but this is a DIY site, no? Gotta give a star or two for using materials on hand. This by the way took all of like 60 seconds start to finish, including finding the bag, it went very easy. – Bryce Oct 4 '16 at 15:14
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As a wireman with 30+ years of experience, I've had to do lots of tricks to complete the task. While a vacuum and rat (plastic bag) works most of the time, it sometimes fails for many reasons. You might want to go the opposite of that idea. Get some nylon string and a living rat from a local store. Be sure to size the rat for the specific size conduit. Get some compressed air from somewhere. I have known them to run 1/4 mile before. And the rat will go fast. Have a helper to dole out string as it enters the conduit. It's best to have a good lead laid out on the ground, because when you start, the first hundred feet will be run in seconds. Good luck 😎

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    Just remember to feed and water the rat and release it when finished. – Chloe Oct 2 '16 at 21:21
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    I've no idea if this would work consistently (what if the rat stays in the middle of the system?) but it's ingenious even if it doesn't. – enderland Oct 3 '16 at 18:35
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    @enderland If that happens then you need to use an electricians snake to get the rat out. – Freiheit Oct 3 '16 at 18:37
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    @Chloe That's silly - why would you simply release a rat after having gone through all the trouble of training it to pull cables through things? – Crashworks Oct 4 '16 at 1:27
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    @djsmiley2k, yep, trained ferrets were used by Boeing to drag the pull cord for air liner wiring runs. I don't think they do it any more -- not since the Federal Ferret Workers' Union strike of 1964. – Wossname Oct 4 '16 at 13:49
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Another trick that works is to use weed-whacker line. It's essentially really thick monofilament and it turns corners better than fish tape. I've used a lot of it on my boat to pull wires.

  • Heavy fishing line might or might not also work; same idea. – keshlam Oct 3 '16 at 0:38
  • PTFE-insulate wire as well. – Chris H Oct 3 '16 at 13:03
7

In the past I have used

  • micro RC cars - tie the string to the body and drive.
  • hexbugs - (A hexbug is a small oscillating, buzzing "robot". The oscillation in combination with its flexible rubber legs makes it move.) tie a string to it (lightweight monofilament) and go for a cup of tea, come back when the bug has gone through the conduit
  • magnets - one tied to the end of the string one outside the wall to pull it through the pipe, doesn't work so well on ferrous pipes :D
  • hoover with a bag and string - as described above
  • small fishing float - tied to a light line, close the "bottom" end of the pipe, flood it and watch the float come up voila pipe traversed.
  • leaf blower and bag and string - similar to the vacuum, more fun to do though, and seems to develop more pressure for pushing the bag.
  • bearded dragon - put him in one end, release live food at the other and off he goes.....just remember to tie a light string to a harness or its basically just a fun run for your lizard! (guilty!)

Hopefully some of these can help you, maybe not the bearded dragon for that size of pipe though.

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    Suction is limited to 1 atmosphere (which cannot be realized), while pressure is not. Same problem as pumping water up out of coal mines: pushing works better than pulling. – Yakk Oct 4 '16 at 13:15
  • Thanks, never looked at why the leafblower was so good, but that certainly explains it:) I have tried industrial vacuum generators, with the sometimes funny side effect of collapsing the piping (not so funny when it has to be replaced, but makes the walls look rather cool:) – GMasucci Oct 4 '16 at 13:25
  • @GMasucci : gecko. Have you ever tried a gecko? Of course that animal is nocturnal, so you'll have to tie the string, put him in, and he'll hide in the pipe until nightfall. Come out at night with a flashlight and grab him.... – Bryce Oct 4 '16 at 15:12
  • Lol not tried a gecko, though they can climb on just about any surface so might be worth a go, and I get a new pet out of it:) – GMasucci Oct 7 '16 at 13:48
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Hack off (cut off) the plug end if it’s too bulky and splice back on on the other side.

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