Probe Start vs. Pulse

When it comes to metal halide lamps, probe start and pulse start reign supreme. But what sets the two apart? 

Starting Probe Electrode vs. Igniter

Probe-start uses three electrical contacts: one starting probe electrode and two operating electrodes. A discharge is sent between the starting probe electrode and one operating electrode. Electrons from this interaction then go toward the remaining operating electrode to start the lamp. 

Pulse-start forgoes the starting probe electrode altogether, instead, using an igniter. This means that it only uses two electrical contacts as opposed to three. This reduces the amount of heat lost. The igniter, located inside the ballast, uses high-voltage pulses to start the lamp and remain lit.

Tungsten Usage

Tungsten is a metal used in electrical contacts due to its high melting point. Both probe-start and pulse-start utilize it in their functions. Over time, probe-start lamps are subject to tungsten sputtering from the electrodes, which blackens the arc tube wall and, eventually, reduces the performance of the lamp. While pulse-start is also subject to this happening, it has found a way to stall the process. Because pulse-start uses an igniter, it heats up the electrodes faster while simultaneously reducing warm up time, thus reducing tungsten sputtering. This prolongs the life of the lamp. 

Which Should You Go With?

Both probe-start and pulse-start are used in commercial spaces due to their efficiency. Pulse-start may offer more benefits than probe-start, but both are viable to be used in this application.