Barry Johnstone / Green Triangle Electronics
Pulling multiple cables through a conduit.
When you are pulling multiple cables through a conduit using a draw cord of rope, it helps to use a cable-pulling swivel. These are available in various pulling strengths, from about 4 to 5 pounds and up. They usually incorporate a bolt that will break off (if necessary) before there is a risk of the cable stretching.
Major telecommunication carriers commonly use various versions of these ball-bearing swivels, but a cabling contractor can buy a suitable one for less than $100.
Pulling multiple cable with a cable-pulling swivel helps keep the cable in place while inside the conduit.
Pulling the cable with a cable-pulling swivel prevents the natural untwisting of the rope or cord that winds the cables together, letting them remain parallel throughout the conduit. (Adding some cable lubricant will lessen the pulling tension and rubbing friction.) In addition, if the conduit is large enough, a rope can be pulled in for future cable pulling.
- Attach the pulling rope to the swivel with a round turn and 2 half-hitches. Apply a couple of wraps of electrical tape to the trailing end of the rope.
- Using a section of rope approximately 2 meters long, (about 61/2 feet) tie one end to the opposite end of the swivel using the method in the previous step.
- Using several rounds of electrical tape, connect the other end of the 2-meter section of rope to the cables, approximately 600 millimeters (about 23 1/2 inches) from the end.
- Tie 4 to 6 half-hitches, spaced about 100 millimeters (4 inches)apart.
- Keeping the rope firmly pulled tight, wrap several layers of electrical tape around the end of the cables and the pulling rope. This will let the cables follow the pull of the rope, starting off with the knots pulled tight.
- Add some cable-pulling lubricant if necessary, then begin pulling, keeping in mind pulling tensions.
- When finished pulling, cut off the ends of the cable that were damaged by the pulling and pressure of the rope.
Barry Johnstone is a field supervisor with Green Triangle Electronics, Mt. Gambier, SA, Australia.
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