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LCN December 2006 Landscape Lighting11-28-06 | News



The Art of Lamp Selection

By Perry Romano, IESNA, LC

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T3/T4 halogen lamps are the most popular lamps for paths and walkways, and in small high-performance floodlights. They produce an intense white color and are available from 5 to 100 watts. Normally they do not exceed 50-watts and lamp life varies from 1,000 to 4,000 hours.


Installing lighting for residential projects poses a number of obstacles for landscape contractors. Each landscape element poses a distinctive lighting challenge and requires a unique lamp solution.

Lamp choice largely determines the lighting performance, pattern, color, and fixture size for a project. Consideration must also be paid to lamp burning hours and wattage. In most cases, incandescent low-voltage lamps are available with standard filaments or gas-filled halogen quartz-glass-enclosed filaments. The combination of a filament and halogen gas produces bright, intense, noticeably white light with up to four or five times the burning hours of a standard incandescent.

The hour rating given to a lamp is only an average, with factors such as color, brightness and whiteness all playing a part in the deterioration of lamp life.

Vibration or shock by voltage swings and power surges can also shorten incandescent lamp life. Furthermore, in low-voltage lamp systems, inadvertently exceeding recommended voltage by just 10% can reduce lamp life by 65%.

In low-voltage landscape lighting, commonly available and reliable lamp choices are typically the following types:

Lamp: MR8/MR11/MR16 – Color Temp: 3050K/ 2950K/ 3300K

These are used for landscape highlighting and pinpoint light control. Small-size integral units can be hidden in leaves, low shrubs, and trees. A wide range of wattages, beam spreads, and sizes are available along with an array of colored lenses, light-shielding or beam-shaping louvers and shrouds.

MR Series 12-volt halogen lamps are available from 10- to 75-watt sizes. Lamp life is excellent, up to 5,000 hours, lowering maintenance costs and callbacks.

Lamp: PAR36 – Color Temp: 3000K

This has a wide, less intense beam that is excellent when used close to facades; low, wide shrubs; underwater highlighting; and in-ground well lights. Par36 lamps are available in 18- to 60-watt ranges. They can be purchased in standard incandescent, with lamp life as low as 300 hours, or in halogen with a 4,000- to 5,000-hour lamp life. Due to their larger size, Par36 lamps are less popular than MRs, but are very reliable.

Lamp: T3/T4 – Color Temp: 2950K/ 2700K

This is the most popular lamp for path lights, walkways, and in small high-performance floodlights. Since this lamp is halogen, it blends well when used in an overall installation with MR Series halogen lamps. All lamps will produce the same intense white color. T3/T4 lamps are similar to MR lamps without the reflector, so they require a fixture with one.

Lamp: SC Bayonet & Wedge Base – Color Temp: 2700K/ 2950K

This is another ?EUR??,,????'??bare?EUR??,,????'?? lamp for small path-lights or small reflectors. These lamps originated from automobile 12-volt systems and found their way into low-voltage landscape lighting. The advent of halogen lamps has reduced need for this lamp. The lamp is rated at 1500 hours and produces a warm yellow tone, typical of standard incandescent lamps.

Lamp: LED (Light-Emitting Diode) – Color Temp: 2700K ?EUR??,,????'??? 6400K

This is ideal where color effects and programmed color changes are sought, especially for pools, fountains, or certain plantings. Units are sub-miniature, very low watt (often .5 to 1 watt per LED), very long life (50,000-plus is the standard). Fixtures require reflectors to shape and project the light. LEDs are usually clustered, requiring replacement of whole clusters at one time.



Illuminating Info

1/2 to 1: Foot-candle of light, the illumination level of the average residential street lighting project.Traffic areas such as sidewalks and steps should also be lit to approximately 1/2 to 1 foot-candle.

5 to 7: Foot-candles of light, the illumination level of a well lit tree or statue. Source: www.landscapelight.com

100,000: Hours, the lifespan of solar lights, compared to 2,000 ?EUR??,,????'??? 3,000 hours for the average incandescent light. Source: Alliant Energy




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