How to Use: Gen sets/light towers

It’s natural for you to put a great deal of thought into the acquisition, operation and maintenance of your heavy equipment fleet, but doing the same with your light equipment can also boost your bottom line.

Making the right choice
Choosing a generator or light tower can be a critical decision, particularly if you power multiple tools from the gen set. The right light tower is key for evening work on the jobsite as well as for security needs. A few calculations and some spec comparisons before you choose will save headaches in the long run.

Power up
Whether you need a 1,000-watt or a 10,000-watt generator, basic knowledge of the average wattage requirements for your tools helps you determine the rated power you will need from the unit. Remember, though, the wattage required for starting a tool can be several times higher than the wattage required for running the tool. For average wattage requirements for common tools, see the chart on page 76.

Fans, pumps and compressors can require up to five times as much power to start up as they do to run continuously, says Dean Van Riper, corporate marketing, Baldor. “Start up power requirements should be factored into your sizing measurements,” he says. “Check equipment nameplates to determine wattage requirements.” If no requirement is listed, Van Riper says you can calculate wattage using amps and volts by using the power equation Amps x Volts = Wattage. “For example, 12.5 amps times 120 volts, equals 1,500 watts,” he says. “It’s a good idea, however, to add a 10- to 20-percent sizing margin for powering larger wattage tools if needed in the future.”

When choosing a light tower, know approximately the size area you want to light and choose a unit with features to fit your application. Light masts that are easy to extend can be raised and retracted by just one person, and hot-dipped galvanized sections prevent binding, friction or rusting, Van Riper says. Look carefully at the lamps themselves. “Metal halide lamps mounted in an elliptical fixture provide improved coverage,” he says.

Metal halide lamps are more popular than high pressure sodium lamps, says Dean Mathison, product manager, Magnum Products. “They’re basically the industry standard,” he says. “Metal halide lamps provide a bright white working light good for a jobsite. High pressure sodium gives off a more pink light – similar to street lamps. They’re also slightly more expensive.” Mathison says Magnum’s customers choose the metal halide option 99 percent of the time, but cautions that while the lamps are great for the jobsite, the bright intensity of metal halide lamps can cause visibility problems for oncoming traffic. Van Riper says to note the high wattage metal halide lamps take up to five minutes to start and up to 20 minutes to restart.

Light towers also come standard with outriggers for stability in high winds – most towers are rated to withstand between 50 and 60 mph winds. Also consider maneuverability on the jobsite and fuel tank capacity and compare them with your requirements.

Rent or buy?
Once you’ve decided what you’re looking for in a gen set or light tower, decide if you should rent the units or buy them. Generator rental costs vary widely, depending on the size unit you need, says Jordan Paulk, account manager for W.W. Williams in Phoenix, Arizona, a Terex dealer. “Generator rental costs can range from $1,000 per month for a 30 kW unit, $8,000 monthly for 400 kW and up to $32,000 per month for a 2-megawatt generator,” Paulk says. “If you reach a long-term rental point, though, you may want to look into purchasing one.”

John Gibbons, sales manager for light towers, generators and power buggies, Terex, agrees. “The general rule is that if your rental period rate is more than one-third of the purchase price, then it’s time to consider buying a generator,” he says. Gibbons cautions that maintenance is also a factor when making the decision to buy. If you don’t have the capability or manpower to perform maintenance, stay with the rental option. “Generator maintenance is an important consideration: in addition to engine servicing it includes electrical testing for verification of proper operation plus full load bank capability to prevent wet-stacking – over-fueling caused by running diesel engines with light loads for long periods of time,” Gibbons says. “Typically the rental house can provide better maintenance in these instances.”

Easy operation
Carefully follow manufacturer instructions when using a gen set. Keep in mind ventilation is crucial, so place the unit in an open area on a firm, level surface. Run the generator at least once a month to circulate oil for engine lubrication, run fresh gas through the carburetor and recharge the battery.

Gibbons says for light towers, preventive maintenance is key, and by keeping to a maintenance schedule, you can add years to the life of a tower. “Probably the most important maintenance tip to keep your light tower running is to make certain the engine is set at a constant rpm recommended by the manufacturer, with no load,” Gibbons says. “This ensures good, clean voltage and longer life from the ballasts, generator and light fixtures. If the engine speed is not maintained, the lights will run at higher voltage and burn out quicker.”

Gibbons notes you should also crank the engine before the light switches are turned on, then shut down all breakers prior to shutting down the unit, preventing the electrical equipment from being subjected to improper voltage and frequency.

Check engine oil and coolant levels weekly on new or nearly-new machines and more frequently on older towers. If the temperature falls below freezing, add anti-freeze to the coolant or remove it before damage occurs to the cylinders and radiator.

Straightforward troubleshooting
Awareness of common problems that occur when using gen sets and light towers makes troubleshooting simpler, Mathison says. “Make sure your generator output isn’t too small or too large for your application.”

Loose wiring or battery connections, water in the fuel and failing to have the unit leveled or grounded creates problems in both gen sets and light towers. Mathison also recommends choosing a light tower with individual ballast lights to make servicing faster should a light circuit fail.

Productive performance
You can choose from a wide range of factory-installed options to enhance your unit’s efficiency. For example, if you frequently work in cold weather, Marc Leupi, utility product manager, Wacker, recommends a cold weather package for generators. “The package’s temperature-activated shutters, block heater, electronic governor, LCD strip heater, lube level maintainer and low coolant shutdown keeps the generator operating at peak performance all year long, even under extreme low temperatures,” he says.

Van Riper says checking frequency and voltage regulation on larger gens contributes to improved load performance. “Mechanical governors should have no more than 5 percent frequency regulation, and most electronic governors will regulate frequency to within a half percent,” he says. “Voltage regulation should be a low percentage figure – 1 to 2 percent on average is best.”

Steve Bailey, assistant vice president, Honda Power Equipment, says inverter technology, which processes raw power through a microprocessor for ultra-clean power, reduces size, weight and noise. “An Eco Throttle feature varies engine RPM to produce only the power needed to operate the equipment,” he says. “This feature improves fuel economy up to 40 percent compared with traditional generators.”

For light towers, Mathison suggests maximum stability outriggers and convenience outlets. “Multiple convenience outlets and generator options with 6kw to 25kw in single and three phase allow for varied product applications,” he says.

Whatever options you decide on, Paulk advises you talk with your rental representative or dealer prior to making a decision. “Keep it simple. Figure out your needs and don’t get talked into features you may never use,” he says.


Light tower safety tips

  1. The area immediately surrounding the light tower should be clean, neat, and free of debris.
  2. Position and operate light tower on a firm, level surface.
  3. Never start a unit in need of repair.
  4. Lower tower when not in use, or if high winds or electrical storms are expected in the area.
  5. Make certain light tower is well grounded and securely fastened to a good earthen ground.
  6. Make sure area above trailer is open and clear of overhead wires and obstructions.
  7. Bulbs become extremely hot during use. Allow bulb and light fixture to cool 10 to 15 minutes before handling.
  8. Keep area behind trailer clear of people while raising and lowering mast. Never raise, lower or turn mast while unit is operating.
  9. Trailer must be leveled and outriggers extended before raising tower. Outriggers must remain extended while the tower is up.
  10. If any part of the mast hangs up or winch cable develops slack while raising or lowering tower, stop immediately and contact a service representative.
  11. Never remove safety pin or pull mast locking pin while tower is up.
  12. Never use tower if insulation on electrical cord is cut or worn through.
  13. Never operate lights without protective lens cover in place or with a lens cover that is cracked or damaged.
  14. Never adjust mast while unit is operating.

Source: Magnum Products