I killed my Sylvania 800w Retrofit lamp by running it from a CWA ballast . It ran for about 10 min. before it started cycing .

Thank you all for your replies! I am new here and I am just discovering how helpful the community here is.

Thanks for letting me know! I was ready to try it but now I won't. If only HX ballasts were more common... 

Thank you so much for letting me know! I didn't know that the type of impedance mattered.

Update: i tried fixing it anyway. Replaced the emitter resistors, the fuse and the transistors. It still doesn't work. It does oscillate - i hear the interference whine on the radio -  but nothing appears to be happening with the tube. Need to do more measurements...

Erythemal radiation and germicidal radiation are two different things. Germicidal radiation (254nm mostly associated to low pressure lamps) just causes strong skin/eye burns and does not induce suntan. It belongs to shortwave UV-C range. Erythemal radiation belongs mostly to UVB and some short end of UV-A, it causes milder sumburn in large doses and induces suntan and vitamin D synthesis.

Yes, regular glass envelope filters out most of shortwave radiation of a mercury lamp, UVA part generally passes but is not considered harmful, though it induces yellowing in many materials.

Built a focussing system for the Eye H50 at work, that's used for hexane or hexene and bromium to show subtitution reactions.
The Narva NF80-in-a-can is a bit more powerful and also potentially overdriven a bit (though no blackening of the arc tube is visible despite a good 15 years of occasional use), but has no system to concentrate the light or use any light radiated from the back - so with a bit of luck, the reaction happens as fast with the tiny 50w lamp, as it does with the 80w one.
 

Correct, better known as erythemal radiation, but as I understand it, you won’t get erythemal radiation exposure from viewing a clear mercury lamp as most of this radiation is filtered out by the outer jacket?, its only the bare arc tube itself that can harm skin and eyes.

It is just not wise to look at bright light sources for prolonged time because the eyes are sure not replaceable

There are enough idiots in the world who damaged their retina by looking at the sun, and many HID lamps arcs are at about the same brightness.

It is not arc eye, as was said before. Until you are messing with germicidal or not UV-blocked pure quartz lamps, or arcs in the air, there is not much UV to cause this.

Arc eye hurts on the surface of the eyes (and skin) and is generally recoverable, at least if not extreme doses. But retina burns from lasers and sun are permanent.

 

Yes, reducing CWA ballast capacitor was used in US to dim street lights (though to less extent than you propose), BUT by reducing ballast bapacitor you are going more and more into pure capacitive ballast territory, where capacitance dominates ballast impedance. And it was learned many years ago, probably 100+ already) that discharge lamp do not work well on capacitive ballast on line frequency, because combination of leading impedance and lamp's negative resistance is causing current spikes and oscillations. And so high current crest is killing the electrodes. Already somewhat noticeable on stock CWAs. So better don't, just get a 175W ballast, they are ubiquitous.

AFAIK, American 175W mercury and MH lamps are homologated by running current and voltage, so mercury lamps can be run on MH ballast. There may be some nuances with OCV (not much relevant to merc lamp) and use of ignitor.