400w xm bulb on hqi ballast?

[Thales]

Hey Sanjay,

I have been running 400 watt 20k xm's on a Dual 400 HQI PFO ballast. Table two in part 5 of 'Facts of light' recommends an m59 ballast. So, are there any problems running the bulb ballast combo I am running now? Is it worse for the bulb? Does it effect out put? Should I change everything?

Thanks!

RR

[Sanjay]

Well, you are very likely overdriving the XM 20K lamp with the HQI ballast. It will usually result in reduction in lamp life. With 20K lamps most people change in 8-10 months or less anyway, so the life may not be much of an issue.

Sometime overdriving the lamp will result in lower output from the lamp too. I have seen it in a few of the lamps I have tested, where the lamp actually perormed better on the M59 ballast than the "HQI".

I would not change everything.. as long as you are aware of what you are doing and mindful of the down side.

sanjay.

[Thales]

Thanks Sanjay!

I happen to have some m59's, so when I get around to it, I will change out the 'HQI''s.