Ted Todd, Todd Communications Inc.
Problem
Pulling cable through old conduit can be difficult for several reasons. The pull rope may no longer be in place, and the conduit may already contain cabling. Either of these situations can make pulling new cable through the conduit a challenge.
Solution
You can use an industrial-strength vacuum cleaner to pull a plastic bag--with an attached string--through the old conduit. You can then use the string to pull the new cable through the conduit.
Procedure
1) Fit the hose of an industrial-strength vacuum onto the pull end of the conduit. Secure the hose with duct tape.
2) Turn the vacuum on. This will produce air flow through the conduit.
3) At the feed end of the conduit, tie a reel of strong kite string to the handles of a plastic grocery bag.
4) Place the bag inside the conduit.
5) As the bag gets sucked through the conduit, the kite-string reel will spin. When the reel no longer spins, the plastic bag has made it through the conduit and into the vacuum.
6) Cut the string at both ends of the conduit. You now have a pull string to which you can attach the new cable.
Ted Todd is co-owner and president of Todd Communications Inc. (Winston-Salem, NC).
Insert a plastic shopping bag, tied to a reel of kite string, into the feed end of the old conduit.
Secure the hose of an industrial-strength vacuum cleaner to the pull end of the conduit with duct tape.