I can see 'Belgium' there, so I suspect you're right about it being Philips-made. Also the Philips date code, although a lot of people used that system in later years.

Yeah the lamp being made in Belgium and the date code screamed Philips made to me.

I have a 125w MV also from the same era (I'm pretty sure with the same date code) but with Philips branding and the etch in the neck instead. Looked like it was intended for the European market that got exported to Canada.

I have this one in the Collection and there is an interesting background story about it and its system. In the mid-1970s AEL released the SC175M mercury vapor luminaire (175 referring to the total system wattage) based on a proprietary low-voltage 140 W lamp driven from 120 V mains via a series choke ballast. This unusual system was developed as a low-cost mercury variant to the 52-55 V HPS lighting systems that were introduced in North America at that time. The problem, however, is that in order to ensure a reliable ignition the probe in the mercury lamp had to be placed very close to its adjacent (main) electrode, which resulted in a significant risk of early failure due to mercury condensation and bridging between those two electrodes.

Because of this reliability issue and the higher cost of the lamp, which was specially made by Philips, AEL replaced its SC175M system by the SV-175M around the late 1970s or early 1980s, still with a 140 W mercury lamp, but of the high-voltage type this time. The series-connected inductor was then replaced by a small transformer ballast delivering just enough voltage to ensure proper starting and operation of the lamp. That light source, shown here, is a standard European Philips HPL-N 125W fitted with an E26 end cap, which reduced production costs considerably. Over-driving that lamp 12 % above its nominal wattage rating results both in a shorter mean service life (12 kh instead of 24 kh, a reduction also caused by the higher current crest factor of the American ballast) and in a higher lumen output (a little over 7 klm). The latter is consistent with AEL's claim that its lamp “delivers more light than four 100-watt incandescent bulbs on 65 % less energy”, meaning more than 6920 lm on 140 W exactly.

Because of its design, the SV175DX is also compatible with 125 W H42 ballasts, and can also be run on the more standard (in NA) 100 W mercury vapor lamp systems (H38 ballasts, more specifically in the company's DR100M-1, the CSL-MVA, and the ICI-115-1000 luminaires), with the benefit of a longer service life. This thus made it effectively a triple-wattage lamp: 100 / 125 / 140 W!

Thanks for the detailed writeup about the history of this lamp. I remember coming across on a post about the Lo-Volt mercury lamps and their problems and I had a hunch this was the successor to that system but it's nice to confirm that was the case. Interesting that these were also compatible with 100w H38 ballasts as well. I might have to pick a couple more up the next time I'm there.

IIRC I believe the store I bought them from labelled these as "125w mercury lamps" which I suppose is the most accurate.

This is indeed a technically correct description of the lamp.

My piano teacher had an AEL Lo-Volt MV bucket light on her home from around 1992 to 2022 when it was taken down in favor of a Lithonia LED utility light... She ran it up about 5 nights a week, and got about 10 years out of that first lamp. She wound up relamping it with a medium-base 100w lamp sometime around 2004, which lit reliably without issue for about ~11 years before the ballast died. I doubt she had any idea what lamp(s) she should've been running, which probably would've applied to most consumers at the time...
Unfortunately, I didn't think to ask her for the luminaire at the time...

Another common issue I've noticed was that the lamps in these lasted so long that unless you bought a couple of replacement lamps when you bought the fixture, by the time the original lamp needed replacement, you'd be hard pressed finding a replacement from the store you bought the fixture from, either they never/stopped stocked the replacement lamp or they discontinued it.

At least with standard wattages you were able to find elsewhere but non standard wattages or something proprietary such as the Lo-Volt you'd be hard pressed to find, especially before eBay.

I'm surprised the Lo-Volt fixture even worked with a 100w lamp. Some used a modified HPS ballast choke so I'd imagine regular 100w lamps would have cycled.