Two metal halide fixtures were accidentally re-lamped with HPS lamps. We were going to switch them back to MH lamps, problem is the HPS lamps are working fine and the HOA wants them in all the fixtures now. I don't even know how they are working with no igniter, but they are working. Not sure how long though, it's only been 3 weeks. Anyone know why they are working and if they will hold up?

Maybe the fixtures were originally HPS and were lamped with MH?

could they be a conversion lamp

http://www.eyehortilux.com/products/Conversion-Lamps

nope, just plain old HPS lamps

There are many varieties of Pulse-Start Metal Halide Fixtures available for Lamp Wattage of 35 Watts up to 400 Watts.

AFAIK, the PSMH Ballast Kits use the same Pulse Ignitors as HPS Ballast Kits - per Lamp Wattage.

--Scott (EE)

Probe-start MH ballasts do not have ignitors, but they are an older (though still current) tech. Pulse-start (new tech) ballasts DO have ignitors.

As to what the fixtures are actually supposed to be, check the transformer for the ANSI code... prefix M for MH, S for HPS. It's typically a letter and two numbers, like M47 or S55.