Published: October 2006
THERE WAS A TIME WHEN PULLING WIRE must have been one of the most labor-intensive and frustrating jobs electricians were called on to do. imagine gangs of men physically ulling runs of cable on large commercial or industrial projects. Cable pulling equipment has changed that.
While cable is still pulled manually on residential and light commercial jobs, new lightweight power pullers bring cable through conduit on a variety of projects, and larger power-pulling tools are used for making long, multiple-cable installations. The same pulling equipment used for electrical cable also can pull datacom cabling. However, characteristics of datacom cable must be considered, more load control may be required, and monitoring pulling force is important.
“With the introduction of lightweight, high-speed pullers into the market, manual pulling represents a loss of man hours the moment you pull a rope into the conduit,” said Brian Ray, president of Ray Tools.
Many puller choices available
Cable pullers are available in different sizes with pulling capabilities ranging from 1,000 to 8,000 pounds. A variety of pulling accessories is available to make pulls easier and more efficient. Basic components of most power-pulling tools include frame, power source, the capstan that pulls rope and wire, the mechanism that turns the capstan and pulling rope.
“The differences between pullers emerge with how these components are mounted, the speeds with which they are set up and ... the number of accessories required to make certain types of pulls,” Ray said.
Mark H. Benning, Gardner Bender senior product manager and channel marketing manager, pointed out that smaller-rated pullers may use a drill or pipe threader to power the pull.
“For larger-rated pullers of 5,000 to 8,000 pounds, motors are mounted directly inline with the frameworks to assure structural safety during the pulling process,” Benning said. “Typically, heavier duty cable pullers are required for pulls driving resistance greater than 1,000 pounds. When pulling at a greater force than 1,000 pounds, it becomes more efficient to use powered pullers to get the job done safer and faster.”
Benning said most problems encountered during pulling operations are caused by improper setup and use. The cable puller must be installed and checked prior to its use to ensure proper application, setup and use. He added that most manufacturers provide instructions that demonstrate setup for almost every application encountered. Safety precautions are always stated in the instruction sheets.
Jim Eisele, Greenlee Textron senior product manager, said manual-pulling tools are basically unchanged, but he points out that today’s power models have new features.
“One is mobility,” he said. “Some pullers come with rugged wheels for easy mobility and can be folded up and lifted by one person, either onto or off of a truck.
“Versatility is another new feature—newer pullers allow the end-user to up pull, down pull and make side pulls with the adjustable elbow and extendable boom. Contractors also have said they are looking for a cable puller and no loose parts that can attach to all conduit sizes quickly and easily,” Eisele said.
Eisele said mixing components of pulling tools invites problems.
“Like a chain, a pulling system is only as strong as its weakest link, but pullers often use components that are not rated to work together,” he said. “The capacity of the puller should drive all other component selections. Sheaves, for example, are often undersized for the forces they must exert. If the end-user is pulling a 2,000 lb. load over a 2,000 lb. capacity sheave, the actual load is 4,000 lbs. Make sure that mounting points for sheaves can withstand the heavy pulling forces. Anchor to the solid structure, not to a tray or the ceiling grid.”
Eisele said that more pullers are being designed with built-in safety features, such as right-angle sheave to keep the operator out of the direct line of the pulling rope and a circuit breaker on the puller motor so that if the puller becomes overloaded, the motor will shut off automatically.
John Ireton, HIS Business Manufacturing, said manufacturers design cable pullers with various features and benefits.
“Some,” he said, “are single-speed, chain-down models, which are adequate for general purposes and require minimal training and maintenance. Others are portable capstan-style pullers with features including multiple speeds, self-contained framework with wheels and self-tailing capstans. These pullers are designed for minimum setup time and maximum performance but require more skilled and experienced operators. Evaluating cable-pulling requirements and matching them with the right cable puller can make cable installations extremely productive.”
Paul Pothier, Maxis director of marketing, said power-puller models available today are now so easy to set up and begin pulling that, unless a pull can be easily accomplished without much muscle strain in a short amount of time, a power puller usually is the quickest, easiest and safest way to pull wire. They are lighter than older models, faster, provide more torque and are easy to setup and operate.
“Until three or four years ago,” Pothier said, “the industry was using large, bulky pullers that attached to the floor and were very slow. That changed with lightweight, stand-alone, easy-to-set-up pullers that attach directly to the conduit rather than to the floor and which offer significantly faster pulling speeds.”
Pothier said differences among pulling models includes the range of adaptors that securely attach the puller to the conduit and a power source that is a detachable drill or permanent attached motor. Some pullers are permanently mounted on rollers; others are so light in weight they can be easily carried from pull to pull.
Ray said the trend in power pullers is to make them smaller and stronger with more compact power models being used instead of manual-pulling tools as electricians recognize there is a better way of pulling wire.
“Which puller is used is determined by how much pulling force is needed,” Ray said. “When speed of setup and speed of pull are important, a lightweight puller is ideal. Basically, lightweight pullers are used when a heavy-duty puller isn’t needed. But when you need brute force, only a heavy-duty puller will do.”
In his experience, Ray said, most pulling problems begin with incorrect set up of equipment, typically anchoring, pulling angles, and the ways heads are set up. He believes new, improved equipment is making it easier to avoid these problems and good, local training is an important factor in the correct use of equipment.
Rope is the link between cable puller and cable being pulled, and manufacturers of pulling equipment agree using the right rope is critical to every pulling job. Not any rope will do. A primary requirement is that rope is strong enough to sustain the pulling force necessary to bring cable through the conduit with a breaking point four times greater than the maximum pulling force that can be generated by the puller is a good guideline.
Double-braided composite rope is often preferred because it stretches less and resists heat generated during an installation. Polypropylene rope should not be used because it has a low melting point and friction can cause fibers to melt and stick to the tool’s capstan.
Rope with high stretching characteristics stores energy like a stretched rubber band and a component failure during a pull can unleash this energy, posing serious safety hazards. Rope must be in good condition without kinks or splices and should always be inspected before every pull. Worn or damaged ropes should never be used.
Most pulling applications take advantage of accessories to make installations easier and more efficient. Most common applications are wire grips to connect cable and pulling rope, sheaves, wire carts, reel jacks to control pay out of cable off reels, cable tensions meters, and mandrels to pass through conduit before pulling cable to verify there are no blockages.
In addition, pulling lubricant reduces friction and minimizes damage to cable jackets. Various lubricating products are available to fit varying needs; cream-style products are preferred by many. Correctly using a high-quality lubricant can significantly decrease pulling time.
Evolving products address a basic need
As it always has been, cable pulling is about pulling wire into the conduit the fastest, safest and easiest way possible,
“If manufacturers do not continually update equipment, we are doing our customers and potential customers a great disservice,” Ray said. “We are constantly working on improving ways for electricians to pull wire.” EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or firstname.lastname@example.org
Sheaves to support cable and guide it during the pulling process are among the most-used pulling accessories. When used properly, sheaves can reduce setup time and make cable pulls easier. However, pipe adapter sheaves are sometimes mounted to the wrong structural members, and sometimes they are not mounted correctly. In these situations, the sheaves can be overloaded and serious accidents can result.
There are only two proper use situations for pipe adapter sheaves. They should either be mounted directly to the conduit into which the cable is being pulled, or they should be attached to a mobile T-boom, which also requires an adapter sheave.
Do not mount pipe adapter sheaves to a building's structural members, including beams, posts, columns, pipes, etc. This can result in an overload situation for the adapter. do not attach pipe adapter sheaves to conduit that is less than 2 1/2 inches in diameter; smaller conduit does not have the strength to support the pulling loads. Do not attach pipe adapter sheaves to PVC or alumninum conduit; they do not have the strength to support the pulling loads.
-Summarized from information provided by Greenlee Textron