Two emerging street lighting stars in the night sky are not quite ready for prime time. However, the LED (light-emitting diode) and the triple-tube compact fluorescent lamp show promise and contractors should be aware of them. There are several alternatives to traditional high-pressure sodium for road and parking lot applications.
Metal halide lamps, with their brighter, more constant color output, are getting attention from many contractors.
Basic issues of visibility, economy, safety and reduced light-loss remain, no matter what the technology. In any case, contractors working with city government or utilities should talk “total lifecycle cost” when quoting lighting projects, not just installation cost.
“Contractors using LEDs will find an 80-90 percent savings on power consumption,” said Jeff Oliveros, director of engineering for Sunbrite (www.sunbriteleds.com, Palatine, Ill.). A division of Lumex, it produces a variety of LEDs for applications like railroad crossing lights, street traffic lights and large warning lights.
LEDs have lower power consumption than traditional lights and typically last longer than a traditional bulb. While filament lights might have a 5,000-hour life, LEDs can go 100,000 hours without replacement. That’s about 11 years of 24-hour-a-day use. Typical HID lamps last from 15,000 to 24,000 hours. At 10 hours a day operation, this equates to four-plus years.
There is a downside to LEDs. The cost of an LED array is about 10 times that of a standard bulb, depending on color. LEDs operate on 110 AC. They come in 8-inch and 12-inch arrays and, where they replace standard bulbs, LEDs install on standard E26 or E27 bases.
Oliveros notes many California jurisdictions use LEDs. LEDs rarely burn out, saving a truck roll and labor on a two-person crew. The higher cost is recouped on labor savings. Mainly used in directional arrows, traffic lights or similar applications, using LEDs for overhead lighting is three to five years down the road.
“Triple-tube compact fluorescent lights give a higher CRI (color rendering index) for pedestrian-type traffic,” said David Henderson, manager of new product development for infrastructure and security at American Electric Lighting (www.americanelectriclighting.com, Conyers, Ga.). Like LEDs, they offer longer life than traditional lamps.
Until now, starting temperatures were a challenge for compacts. Today, Henderson said, starting temperatures go below 0 F. However, there is still some improvement needed on lumen output.
Cost of replacing ballasts is hamstringing some of the newer technologies. That means the traditional lighting systems still have a lot of life left.
“There are not many new lamps available for highway applications,” said Liz DeFranco, applications manager for high-intensity discharge lighting with Osram Sylvania Co. (www.sylvania.com, Danvers, Mass.).
“High-pressure sodium continues to dominate highway lighting,” according to DeFranco. “PLUS (non-cycling lamps) would be the ideal lamp to use as they do not cycle,” she adds. DeFranco said she sees is a slight shift over to metal halide in order to obtain a whiter light.
“However the lamp life remains an issue with metal halide,” she cautioned.
A traditional high-pressure sodium light will typically give about 24,000 hours life. Those with two arc tubes can give up to 67 percent greater life than that. The ceramic metal halides typically clock in at about 16,000 hours.
Yet there are major advantages to metal halides. “Ceramic metal halide gives a much better CRI over other lamps,” said Ron Wilson, general manager of discharge products for GE (www.ge.com, Cleveland, OH). He said a typical CRI on metal halide lamps is 85+. GE has 250W and 400W versions of its ConstantColor lamps available today and expects to bring other wattages to market.
“Contractors can spec metal halide lighting right away,” Wilson said. “There is no ballast to change to move to metal halide.” Lights can go anywhere a contractor would install high-pressure sodium lights. Both types of light should be mounted at the same height. Metal halides can be mounted either horizontally or vertically.
There are other advantages. “You get better color than you do with high-pressure sodium lights,” Wilson continued. Contrasted to the pink-orange glow of sodium lighting, metal halides provide a very white output. “The eye is more perceptive with higher CRIs.”
Parking lots and other driving areas where clear lighting is requisite prove to be good markets for contractors installing the lamps. While the metal halide technology is not new (it has been around for 40 years in display lighting) using it for highways is a recent trend. It is also suited to landscape lighting or highlighting buildings.
There is little light leakage. Even though the eye sees the metal halide light as brighter, they actually have about 10 percent lumen output. That is important with the proliferation of “Dark Sky” legislation.
Studies are underway in the UK and Hungary to determine the pros and cons of metal halides. Wilson said early indications show the metal halides, with their constant color, are better received.
“Utilities should be looking at overall life-cycle cost, not just the up-front cost,” Henderson concluded. EC
HARLER, a frequent contributor to ELECTRICAL CONTRACTOR, is based in Strongsville, Ohio. He can be reached at 440.238.4556 or firstname.lastname@example.org.