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Tension Stringing

Tension Stringing?  Be Kind To Your Reels

Putting heavy forces on cable reels during stringing is asking for problems. Here’s why.
Cable reels are made of sturdy materials and appear strong enough to hold up to any task.  But they’re packages, not overhead-stringing tools. Be careful that your reels are used for the right purpose, particularly during tension stringing. However, using the cable reels as a tensioning device is not a good idea.

Reels aren’t built for tensioning
Reels are designed to hold the weight of the conductor but not the force of the stringing tensions.  Reels are excellent shipping packages, but they don’t have the strength to handle the required stringing and braking tensions during stringing.  Reels—whether wooden or steel—are not designed to withstand the forces exerted on the reel flanges and drums during tension stringing operations.  This is especially true for wooden reels as well as older steel reels.  The older the reel, the greater the chance of failure.
The basic standards for cable reels are spelled out in NEMA packaging standards WC-26 and the Aluminum Association “Packaging Standards for Aluminum Conductor and ACSR” Publication #53.  The Aluminum Association Standard, while out of date, is the primary one used for defining the packaging of bare overhead conductors. This standard specifically states that reels cannot stand the braking tensions required during tension stringing installation.

Use a bull wheel tensioner for tension stringing
A bull wheel tensioner should always be used as the holdback to provide tension control and braking force on the conductor as it pays out through the stringing blocks.  The bull wheel can withstand the forces of stopping the conductor quickly in an emergency while, under these same conditions, reels are subject to failure.  Braking on the reel should provide only the force required to keep the conductor taut as it enters the bull wheel and to keep the reel from freewheeling when the bull wheel stops.
In addition, a bull wheel tensioner can eliminate a potential damage problem when tension stringing conductors.  Excessive pull off tension on the reel can cause the conductor to be wedged into the underlying layer of cable on the reel resulting in conductor damage and surging during the stringing operation.  Use of a bull wheel tensioner reduces the forces on the conductor and reel, thus minimizing or eliminating this problem.