How to Fish Wires Through a Conduit or Pipe

Last Updated: April 26, 2020

Suppose you have an existing pipe or conduit for electrical wires, speaker wires, phone or internet cables. Trying to push something through the pipe will undoubtedly just leave you frustrated. Pulling is the only answer. But, how do you pull another wire through that pipe?

Steps

1
Unwind several feet of the light string and feed a little bit of it into one end of the pipe.^{[1]
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2
Start up the vacuum cleaner and attach it to the other end of the pipe. Try to seal the connection the best you can to make the most efficient use of the vacuum. The vacuum should pull the string through the pipe.^{[2]
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- Watch the end where the string is feeding into the pipe to make sure it doesn't get snagged and stop. It is important to be aware of how much string has been pulled in, so you know when to expect the string's exit on the other end.
- Watch the end where the vacuum is for the appearance of the string. If you don't, a lot of string can be sucked into the bowels of the vacuum cleaner.
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3
Once you have pulled the light string through the pipe, attach a heavier string / rope to the end, and pull this through manually.
4
Once the heavier string / rope has been pulled through the pipe, attach your final wire or cable, and pull this through manually. If needing to pull more than one to three smaller wires, connect wires in such a way that the point of connection to the heavy string is not a single "clump of wires" folded over. This will make for a difficult "pull" through the conduit. Instead, connect only one wire directly to the string, create one or more loops in this wire 6 - 8 or more inches down the wire from the connection point. Slip any additional wire(s) several inches into the loop, fold over and wrap around the first wire. Repeat this as often as required and wrap electrical tape around the string / rope just above the connection point all the way down just beyond the last wrap of the last wire hooked through the loops. The result should look like the end of a pencil and will pass much easier through the conduit.^{[3]
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5
Use a metal or fiberglass fish tape or snake. If the conduit run is long, has several bends, has more than 25% of its area filled with wires, etc., the strength and flexibility offered by a fish tape or snake will make pushing into the conduit much easier. Often times it can be used to pull new wires directly into the pipe - saving time of multiple pulls of increasing strength string / rope. Fiberglass does not conduct electricity and is highly recommended for use instead of metal fish tapes and snakes.^{[4]
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Community Q&A

Question

Why am I having problems getting fish tape to go through a 4-inch conduit with two 1/2 inch diameter cables already in the conduit?

Community Answer

The existing cables are not likely to be laying neat and flat in the bottom on the conduit - rather they have several twists around each other over every few feet. This makes getting a snake through the pipe difficult. You can damage the insulation of the cable if you force it through - and if you are able to get it out the other end of the pipe, you have to pull it and the wire you connect to the snake slowly so as not to wear down the cable insulation from friction of dragging new cables over the existing cables.
Question

What do I do if my pull string breaks?

Community Answer

Try again, there isn't much you can do. Just pull the cable out and the string out the other end.