When you run a fish tape/rod from an above location, you must locate the end of the fish tape/rod at the desired lower location. If you are working alone and want to drop the tape/rod a number of stories down a shaft or return duct in a house, it is difficult to guess where the end of the fish tape/rod is located.
Use a small magnet and a compass to pinpoint where the end of the fish tape/rod is located at the lower location. The magnet in the needle of the compass is normally attracted to the magnetic north pole. Your magnet at the end of the fish tape/rod gives a stronger signal, and diverts the needle from the magnetic north pole. Now the needle will point to the magnet attached to the end of your fish tape/rod instead.
- Tape a small magnet to the end of the fish tape/rod.
- Run the tape or rod down the wall (magnet end first) until you think you have reached the bottom of the wall.
- Next, go to the desired lower location and move the compass in a horizontal motion along the wall. The needle will point to the magnet.
- Finally, move the magnet vertically up and down. When the needle is perfectly level in the compass, you have an exact location to cut your hole.
Since this method of fishing a wall requires the use of a magnet, you should take measures to keep electronics (such as your electronic watch) at a safe distance to protect them.
Paul Klein is an operations manager at Dr. Dialtone Inc. headquartered in Alexandria, VA, Dr. Dialtone Inc. provides telecommunications services to commercial and government customers in the Washington D.C. metro area. Klein may be reached at email@example.com.