Caution! Never look directly at the arc tube / arc. A special camera was used with protective lenses. UV output and intense light will damage your eyes!

Probe Start MH / MV

*Lamp may cycle once or twice before lamp finally stabilizes

Mercury vapor and probe start metal halide bulbs use the peak voltage/OCV to start the lamp. When the arc between the main electrodes is started this causes a lot of wear on the electrodes. When the arc has stabilized and the lamp is operated horizontally this causes the arc to bend. Some horizontal lamps have curved arc tubes for this reason and to improve light output for horizontal operation.

Ignitor / Pulse MH

*Lamp may cycle once or twice before lamp finally stabilizes

Ceramic MH, standard European MH, pulse MH, and double-ended normally use this method for starting. This method usually provides better lamp life and lumen maintenance because the ignitor causes less stress on the main electrodes vs. probe start (the ignitor uses high voltage but less current). Bulbs designed for ignitor + ballast should not be used on standard American ballasts (probe start). This can cause excessive stress on the electrodes or the ballast will not be able to start the bulb. SOME probe start bulbs seem to operate on ignitor + ballast systems but some bulbs arc inside the bulb other than the arc tube. This may shorten the life or even short the ignitor. If the bulb was made in Europe and the specs say to use 4kV for starting than an igntior must/should be used.

Drawings, text, and pictures by: Paul Erik Hirvonen