Just obtained my two F20T12 Grey end capped Philips lamps, and my Sylvania GTE lamp, all three Halophosphate Cool White.
Swapped out both of the LPF Trigger Start ballasts that came with the F20T12 fixtures I've got, for the cold temp versions, successfully.
I was in the middle of comparing the brightness levels of the LPF and HPF ballasts at one point though, but that was short lived... found
out the hard way that not only are both of my F20T12 Philips lamps used, one of them was actually right at EOL. The end blackening did not
indicate this, but then again, both lamps have electrode filament shield guards.
The lamp that went EOL was actually on my HPF Trigger Start ballast as it did so. Rough start up, with very bright filament glow as soon as
the lamp fired up successfully. The filament hotspot glow disappeared for a while, so I automatically assumed it was a broken filament. Wrong...
the filament was still intact but completely spent... so, complete hotspot movement occurred, the end blackened completely, and the lamp went EOL.
Brilliant orange flashing at the bad end as expected... but it dimmed down to start-up stage, just like any other HPF Rapid Start ballast. Not much
flash with this lamp.
Switched the EOL lamp over to the LPF ballast and not surprisingly, it just sits there and rectifies... nothing more.
To my surprise, the brightness level of the LPF Trigger Start ballast was almost comparable to the HPF cold temp Trigger Start ballast, but of
course, the HPF one was still a tad bit brighter.

Electrode depletion is a possible EOL. Another failure is if the glass walls absorb too much argon, which prevents it from striking. Other times it could start "distilling", where some places of the discharge tube lose sodium and therefore get hotter, which repels more sodium away. Or they could start to leak sodium into the outer envelope. But yeah electrode depletion is probably the most common as far as I am aware.

Most SOX lamps are rated for 18,000 hours, so supposing you run it for 12 hours a day it would last over four years. I assume you are running it less than that, so probably a lot longer than 4 years. Though many different factors play into the lamp's actual lifespan, so who knows. I am sure someone else can chime in on the specifics of that.

Hi!

I know the failure modes of HPS lamps (cycling, sodium loss, etc.) but I don't know how SOX lamps typically fail, since they work more like a fluorescent tube and contain lots of sodium. My only guess is eventual electrode depletion, but I don't know what that translates to in a well used or EOL SOX lamp. Suppose I have a brand new SOX lamp, run for a few hours a week, how long do you think it may last?

Evluma AreaMax.

Damn, beat me to it.

@SussexEuroSOX, there are LED NEMA heads, this is one.

@SussexEuroSOX
Yes, it was an earthquake.
The city I live in had just barely managed to avoid them up until now, but in 2024 we finally became directly affected…
There was hardly any physical damage, but even a little more shaking is enough to be traumatic……

Damn! I don’t think I could handle the ground shaking!

Okay, I just made a request on their page.

Wasn't there some bigger earthquake recently in Japan? Then even if you were further away, even when attenuated, the shake may have reached you...

@SussexEuroSOX
Yes, it was an earthquake.
The city I live in had just barely managed to avoid them up until now, but in 2024 we finally became directly affected…
There was hardly any physical damage, but even a little more shaking is enough to be traumatic……

@James: Here is the spectrum of my Venture MH-DE 70W/UVS/PDX lamp: https://www.lighting-gallery.net/gallery/displayimage.php?pos=-231287
I think that the halide that account for the vapor afterglow is tin, because of the continuous radiation and the fact that tin absorbs the blue part of the spectrum.

Just let me know when you do, I'll let the main guy know.