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.

https://m.youtube.com/watch?v=OaDJhXyMvu0

Video made by LEDVANCE prior to closing their St Marys facility in Pennsylvania. This was made during the glass / filament LED era of manufacturing, as depicted by the products in the video. Hurts to see......

Jeez what the-!

I hope it isn't bothering anybody that I am asking so many questions lately, but I am curious about this one. I was wondering if I can use my 400w MH CWA ballast for a 175w MH bulb and possibly a 175w MV bulb. The ballast currently has a 24 uF capacitor, but I have the capability to go from 0 to 25 uF in 2.5 uF increments, so I would start at 2.5 uF, measure the wattage, then go up to 5 uF if it isn't sufficient and so on until I get the proper wattage through the 175w lamp. I have the following questions:

1: I doubt this would harm the ballast, but if any of you think it will, please explain.

2: This might be a bad question, but MH ballasts can be used on MV bulbs, right?
Thank you for your help! 

Who knows. I'm no arc eye expert, but my eyes hurt from looking at any concentrated light source for too long.

Though coated MV is probably the easiest to look at. Even clear isn't half bad. It's metal halide and HPS that annihilate my eyed.