Safe, productive wire pulling starts with equipment properly sized for the forces that will be generated in the pull; with wires of a certain dimension or weight, productive wire pulling often relies on powered wire pullers.
For high-force cable pulling, many manufacturers recommend using double-braided polyester rope, which has a high strength-to-size ratio and a “low stretch” that stores relatively low energy. Featuring greater capacity than previous types of ropes, such as polypropylene, the polyester rope, which can generally be used for many pulls, has a built-in safety factor.
For conduit pulls, it indicates the tensile strength (the greatest longitudinal stress the rope could bear without tearing apart), which in comparison to the rated working capacity, is often 3 to 1. For aerial pulls, which involve lifting and pulling, a higher 5-to-1 ratio is typical.
Pullers are not designed to pull continuously at the rated capacity as the frames, sheaves, and other components aside from the motor. Puller ratings are, in effect, actually spike ratings, with the puller designed to work at a somewhat lower continuous pulling force.
Most pulls, as a rule, don’t reach the rated capacity because the friction and pulling forces go up as the cable goes into the conduit. And by the last 90-degree turn (if there is one) or at the end of the run, when the highest forces are exerted by the puller, there might be just 10 to 15 feet left to pull to reach the panel or pull box.
To preclude the possibility of a worker being hit by backlash if the rope fails, some pullers have incorporated a safety roller by the capstan so the electrician can stand at an angle to the puller and the force. If there is no angled roller, the operator should stand off in a safe zone at about a 15-degree angle from the rear of the capstan.
Check the rope after each pull and discard ropes that are frayed. Rope could abrade or pick up debris as it is pulled through the conduit if the conduit is not clean or if there is a burr at a coupling. Several days or weeks may intervene between conduit installation and cable pulling, so before you start any pull, check the conduit for water, kinks, and other distortions, as well as for debris. There are many methods of cleaning conduit, including blowing air or carbon dioxide through it; vacuuming; and pulling through brushes, scrapers, or a cleaning mandrel.
To test a double-braided rope to see if it is still good, grab about a foot at a time and push the ends toward each other. If you can compress the rope, it is good; if you can’t, it is a bad rope. This works because double-braided ropes have a center member with a second braid around it. If the rope is overstretched, it becomes taut on the inside and cannot be pushed together because it has become tensioned and would collapse instead. If that happens, replace the rope.
Beyond that test, most ropes end up being discarded when they get caught on the inside of the conduit or duct and tear, becoming the weakest link.
To minimize elasticity—expansion and contraction—during a pull, try to keep the force on the rope as steady as possible. When setting up for a pull, it is important to ensure that you set up correctly, with the forces going into the ground and not into the framework.
For long pulls, use two-way communication to monitor the activity at both ends, with the worker on the machine end keeping an eye on the tension gauge.
For heavy-duty pulling, today’s powered cable pullers can ease the load on a labor-intensive job, boosting productivity. For safety, look for units with right-angle rollers that eliminate need for the operator to stand directly behind the rope pay out, and with tapered capstans that are designed to keep the rope in alignment, preventing crossover during the pull.
For safe cable feeding, don’t jerry-rig two jack stands and a length of conduit because it is easy for the conduit to jump off the jacks. It is much safer to use a dedicated payout system, such as a spindle that turns smoothly while its ends sit on stabilized jacks. Never wrap the rope around any part of your body and keep your feet clear so you don’t get entangled.
Delivering up to 8,000 pounds pulling power, Gardner Bender Brutus-Powered Puller features a planetary gear system that does not use any chains or sprockets, a nonreversing motor assembly, and a versatile frame that can assemble in a virtually unlimited number of configurations to meet any set-up requirement. The unit features a 1½ horsepower motor, nonreversing capstan with backstop brake, two-way power head mounting that adapts to tight corners, and integrated load read-out meter.
The planetary gear system consists of a series of gears in a carriage that rotates around a spline gear in the center (like the sun and planets of the solar system), explained Frank Maletzke, technical service manager. The planetary gears multiply the torque so the input is converted to a greater output. This gearing system creates a lot of force with a minimum amount of input, he noted, yielding more torque at less speed.
The Ultra Tugger Cable puller 6805 from Greenlee Textron comes with the Versi-Boom System that facilitates versatile, fast setups. The system design enables pulling of the wire over the boom right down to the motor, effectively enabling easy pulling of up to 20 extra feet of cable beyond the end of the conduit, for termination and splicing (enough, for example, to reach into a manhole, yet allow the operator to run the puller from above).
The unit, mounted on four wheels, provides 8,000 pounds of pulling capacity. Electricians can roll the unit to the work location, insert a boom-connecting slip-in coupling or attach a screw-on coupling to the conduit, and start pulling, without any additional anchoring. The coupling keeps the boom from moving and directs all forces into the conduit. Safety features include a planetary gear system on the motor that can’t rotate in reverse and a right-angle sheave—enabling the operator to stand to the side.
Accessories include a booster that doubles the pulling speed until the forces reach about 2,500 pounds and then automatically drops to the slower speed, and a force gauge and strip chart for continuous digital readout of the pulling forces and a strip-chart record of those forces.
The new, totally self-contained, Ensley (Rothenberger) Flex-A-Pull 2,000-pound capacity puller (E-445) is a portable lightweight electric wire puller. The unit has an adjustable mast and boom for pulling any of four ways—up, down, right, and left. The pull arm rotates a full 180 degrees. Totally self-contained and weighing 48 pounds, the puller works in conjunction with a Mini-Collins power drive (model number 0.0074) that provides the motor for the pull. (It accepts all other popular power drives on the market, as well.)
The unit, which features quick setup, comes with a positive trigger lock and foot switch, enabling the operator to maintain both hands on the rope, noted Bernie Hengels, director of sales at Rothenberger. With collapsed dimensions of 14W x 12D x 35H and weighing 48 pounds, it has an extended height of 57 inches and an arm length between 34 and 51 inches.
Current Tools, a new company that manufactures power cable pullers and the mobile pulling carts to which they mount, offers a package, Model 8806, that includes an 8,000-pound cable puller, a tower, a T-boom, and 600 feet of rope. The puller does not require any tools for set-up. A Mobile Puller Mount is available as an accessory.
Using it, the puller can be re-located from pull to pull without disassembly, noted John Scovil, company president. The force gauge is mounted on the puller, for ease of reading while pulling. The unit’s simple electrical system consists of three components-the motor, the switch, and the force gauge, which for safety is mounted on the puller. The unit also incorporates a right-angle safety roller.
Working right out of the box, with virtually no set up, Condux CableGlider STD Cable Puller, which is shipped on wheels, comes with a (dial-controlled) two-speed removable power pack, providing up to 6,500 pounds of pulling force (during spikes) at low speed. Typically, notes the company, the puller can run at 4,000 pounds continuously, throughout the day, pulling 9½ feet per minute.
The unit, which accepts all diameter rope, features a pivoting arm and a foot switch. A self-tailing capstan (which accepts 5/8-inch to 7/8-inch rope only) provides added stability without requiring the operator to create back tension on the capstan manually. The removable power pack (which is also available separately) facilitates pulls in manholes or other locations where it is not feasible to use the glider.
Depending upon the model and the accessories, powered cable pullers range between about $1,799 and $7,600. Depending upon the rope’s length and diameter (typically ranging from 3/8 inch to 1 inch in diameter), expect to pay between $625 and $1,250 for a reel.
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