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“Tighter construction deadlines often push contractors to work around the clock,” said Mark Conrardy, sales engineering manager for the Wacker Corp. “Light towers allow work to continue after dark and permit personnel to work more safely at night. When night shifts are not working, maintenance specialists often use the light towers to service equipment, enabling the job to run at full capacity during the day.”
Basic components of a portable light tower include a trailer with enclosed generator, winch-operated mast and light fixtures mounted at the top of the mast.
While trailer-mounted light towers may appear to be very similar, comparisons reveal there are design differences among brands and models. And in general, current models are more durable and easier to transport, set up and use than older ones. Improved mast designs make them easier to raise and lower and light patterns on some models can be adjusted without lowering the mast. Engines that power generators are more fuel efficient and run longer before refueling, meet stringent emission standards, and are quieter than those of a few years ago.
“Today’s light towers incorporate features that maximize their functionality and make them more cost effective for the end user to own or rent and to use,” said James L. Roberts Jr., Magnum Products’ marketing manager. “While light towers are considered a ‘mature’ product, they continue to be refined and updated. Features like ballast indicator lights and electric winch options continue to be added to standard models, making them easier to use than older models.”
“Manufacturers strive to differentiate their products by providing unique, standard features such as sizes and shapes of the light fixtures, warranty, starter protection on the generator, winch designs and more,” said Rita Moore, power product marketing manager for Ingersoll-Rand. Improvements such as auto start-stop and remote aiming capability makes the unit easier to set up and use.”
The coverage of illumination a light tower provides depends on luminaire design and the type of lamps used.
“The luminaire houses and protects the lamp bulb, distributes the light, connects the lamp to the power supply and provides the mechanism to position the light,” Ingersoll Rand’s Moore said. “Luminaires are classified by a numbering system according to the horizontal and vertical limits of the light’s beam spread. Any designation higher than Number 5 is regarded as a wide-beam floodlight.”
How much light do you need?
For light tower lighting applications, the foot-candle is the measurement that is used to determine how much light is needed to illuminate an area or operation in order to best assure that enough light is present to properly and safely support the work being performed (The measurement is based upon the amount of light emitted by a candle when measured at a distance of one foot).
How much light is needed varies greatly with the type of activity.
“The Illuminating Engineering Society of American recommends general construction activities require approximately 10 foot-candles of light to illuminate a defined work area in ideal environmental conditions,” Mangum’s Roberts said. “For loading or unloading of machinery or equipment, 20 foot-candles are suggested.”
For comparison, nighttime sporting events often are lighted by foot-candle levels of 50 or more.
“It is important to recognize that environmental conditions such as dust, rain, fog, snow, moonlight and other factors impact the amount of light that is actually usable or available in a particular situation,” Roberts added.
In addition, levels of usable light are affected by light tower design, the number of lighting units used, the type and number of lamps in each unit, how high masts are raised, and the angle of beams.
Although charts are available to help calculate the number of light units needed for areas to be lighted, Roberts suggests common sense and experience play an important role.
“Every application is different and presents different challenges,” he pointed out. “To assure there is the proper level of light to a work site, it’s best to err on the side of too many, rather than too few light towers. Manufacturers, distributor representatives and rental lighting professionals are available to help determine what type and how many light units will best fit a project’s lighting requirements.”
Light tower improvements
In the past, conventional light fixtures have been round, with the bulbs vertically mounted, which gives off a light pattern with four hot spots in the middle and cool spots in between, said Steve Marshall, Genie Industries product manager. “Our new cast aluminum square shape light fixtures and horizontally mounted bulbs provide better light coverage with fewer soft spots.”
Traditional light fixtures rely primarily on reflected light for their illumination, Wacker’s Conrardy said, while the company’s newest light towers have distinctive elliptical light fixtures which allow the lamps to be mounted horizontally, providing more light to travel directly from the source to the work area.
Ingersoll-Rand’s Moore said metal halide is the most common lamp type throughout North America and other areas of the world where power frequencies are 60 hz. High pressure sodium lamps, with their soft orange color rendition, are good for foggy and dusty environments. Tungsten halogen, similar to quartz incandescent, is used in many areas of the world where 50 hz power is prevalent.
In addition to light-producing elements, other features of a light tower are important and set different brands and models apart from one another.
Conrardy said that overall product improvements are always being made to improve efficiency, ease of use, durability, mobility and safety of light towers.
“Wacker’s new light towers have increased durability of the lighting system,” he continued. “This is achieved internally by utilizing a more advanced, compact 1000W metal halide lamp and improved lamp support. Externally, the housing is less prone to damage due to a sturdier, more compact fixture housing. Operator convenience has also been enhanced. Each light is individually adjustable without tools and can be easily removed from its mounting bracket for transportation thanks to the quick disconnect power cord.”
Marshall said users want light towers that are simple and easy to set up.
“There are no pins and lanyards on Genie light towers,” he continued. “Instead, you will find pins that are permanently affixed to the machine. Some pins are automatically engaged, saving time with setup. A quick-aim system that doesn’t require tools allows the operator to adjust each individual light fixture without the use of tools, and the tilt-actuations feature makes it possible to vertically aim all four-lamp fixtures from ground while the mast is fully elevated. This greatly improves setup time over the traditional machines that require the operator to completely lower the tower to readjust the direction of the lights.”
Magnum light towers have evolved over the past 24 months to incorporate more user-friendly features, Roberts said.
“They include instructions that incorporate more graphics, icons and pictures to identify controls and their functions and how the unit should be set-up, used and taken down,” he said. “Additionally, a start limit breaker reduces the wear and tear on the system, its capacitors, or any items plugged into convenience outlets. Six-point ground contact provides maximum stability to the unit when in use. Lowering the unit two inches has decreased wind resistance and improved visibility when towing the unit.”
New options, Roberts added, include timer-controlled automatic operation that (automatically activates lights at dark and turns them off first light.
Roberts expects continuing evolution of light towers.
He concluded: “Anticipate seeing further improvements in operation and performance of the base model units, increased options becoming available to meet the niche and mass market needs and continued improvement in all areas of quality and product dependability.” EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or [email protected].