Fish Wires Through a Conduit or Pipe
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
- Unwind several feet of the light string and feed a little bit of it into one end of the pipe.
- 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..
- 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.
- Once you have pulled the light string through the pipe, attach a heavier string / rope to the end, and pull this through manually.
- 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.
- 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.
Tips
- Tie a cotton ball to the end of the string to help pull it through.
- Sometimes you will find that it is easier if the wires are both pulled (at one end) and pushed (of just fed from the other end). Then you will need an assistant. Thin wires are delicate and the both the conductor or the insulation can get damaged if pulled too hard. Fat wires can bind inside the pipe (if there are several bends or something like that).
- If you are pulling heavier cables or electrical wires that bind as they are pulled through the bends and fittings of the pipe, you will need to apply a suitable lubricant (often called "soap" by electricians) to the wire as it enters the pipe. Be aware that many household lubricants can do serious and permanent damage to some types of wires and cables (most common wires and cables are PVC insulated), so consult a professional and acquire the proper type of lubricant. Many "big box" home supply centers sell wire pulling lubricant in the electrical department. In a pinch, many diluted household detergents and liquid soaps may be used with success.
- A spinning reel is a great source of easy feed "string".
- If there is already another wire or cable inside the conduit, then it is often simpler to disconnect it and use it as the "pull string". Connect the new wires PLUS two wires. The first extra wire is to replace the wire being used as a pull string and the second is to be left in the conduit as a pull string for possible later use. You can inspect the wire that was removed for suitability for later reuse or scrap.
- If you are trying to put several wires in the same pipe (most often you may need to put two wires), put them together (rather than one after the other and pulling them afterwards through the pipe). Wrap some tape on them so that there is no visible ends (this will prevent the cables getting stuck inside somewhere).
Things You'll Need
- Household vacuum cleaner or shop vac
- Light string
- Heavier string, or light wire that will be strong enough to pull your final wire or cable
