There are two types of metal halide light bulbs - probe start and pulse start
Metal halide light bulbs are used in exterior lighting (parking lot lights, street lights, wallpacks, many exterior lights). They fall under a type of lighting called HID or high intensity discharge lighting, which includes metal halide, high pressure sodium, and mercury vapor.
Lower wattage metal halide light bulbs have always been pulse-start. Only recently have higher wattage bulbs (150 watt and above) become available in pulse-start.
The higher wattage probe-start metal halide fixtures are slowly being phased out. Per the Energy Independence and Security Act of 2007 new fixtures between 150-500 watt can no longer contain probe-start metal halide ballasts
Pulse start metal halide is superior in quality and performance compared to traditional metal halide lamps which use probe start technology. It optimizes the start up process and evenly distributes heat throughout the lamp. The noticeable benefits are faster start-up time, more energy efficiency, better lumen maintenance and longer life.
Probe start metal halide lamps use three electrodes in the arc tube to start the lamp: one starter electrode and two operating electrodes. The starter electrode creates a discharge across from an operating electrode. The electrons discharged jumps through the small gap between these two electrodes to start the lamp. A bi-metal switch disconnects the starter electrode from the circuit after the lamp is started. Every start-up of the lamp causes tungsten from the electrodes to sputter and stain the arc tube wall. This cause lumen depreciation which means the light output of the lamp decreases as it is operated. Over time the arc tube wall darkens and reduces the performance of the lamp.
This weakness in probe start metal halide lamps is resolved in the redesign of the lamp into using pulse start technology. Pulse start metal halide lamps use a high voltage ignitor and the ballast to create a series of high voltage pulses which start the lamp. The ignitor reduces the sputtering of tungsten as it heats up electrodes faster in the start-up process. It also allows the reduction of the pinch or seal area at the end of the arc tube thereby reducing heat loss and warm-up time. The immediate benefit of this redesign is higher lumen maintenance which means lamps can provide sufficient illumination and operate for a longer period of time before needing replacement.
The development of the pulse start technology increased lamp life and energy efficiency comparable to high pressure sodium lamps. In addition, it also produces desirable color characteristics. The extended life of the pulse-start metal halide bulbs will reduce long term lighting maintenance costs
Pulse-start metal halide lamps are now available in a 5000 kelvin color, with a color rendering index of over 90. This makes pulse-start metal halide an attractive lighting retrofit to both high pressure sodium lighting and traditional probe-start metal halide lamps.
Traditional probe start metal halide ballasts run using electromagnetic ballasts. While many pulse-start lights also run off electromagnetic ballasts, they are more efficient, and there are some electronic ballasts available for pulse-start metal halide lights. The electronic ballasts available today are typically only available for the wattage 150 and lower, but higher wattage electronic ballasts are expected to come on the market soon.
In Idaho there are currently incentives from Idaho Power for retrofitting old probe-start metal halide fixtures to pulse-start.
Pulse-start technology is superior to probe-start lamps in almost every measurable way – longer life, better lumen maintenance, faster start up time, greater lumens per watt.
At Bright Ideas Lighting Co in Boise Idaho we are your experts in lighting retrofits of all types including pulse-start metal halide. Call us at 208-378-1889