Because of the fact that many North American 4 foot F40T12 fluorescent tube fixtures have often experienced frequent ballast failures from running 4 foot F34T12 fluorescent tubes, I find the design of many European 32W preheat circline fluorescent fixtures to be very concerning to me for the following reasons:

Many of these fixtures often use 4 foot F40T12 and/or F36T8 preheat fluorescent ballasts.

32W circline fluorescent lamps have very similar electrical characteristics to North American 4 foot F34T12 fluorescent tubes.

F34T12 fluorescent tubes have been known to cause frequent ballast failures in older North American F40T12 fluorescent tube fixtures.

Here are the electrical specifications of the fluorescent lamps discussed above:

4 foot F40T12: 105V arc voltage drop, 430mA operating current

European 4 foot F36T8: 103V arc voltage drop, 440mA operating current

North American 4 foot F34T12: 84V arc voltage drop, 450mA operating current

32W circline: 80V arc voltage drop, 430mA

As far as I have known, the ballast failures in North American F40T12 fluorescent tube fixtures may have been caused by the ballast drawing more current than what it was rated for due to the lower arc voltage drop of F34T12 fluorescent tubes.

Because of these observations among North American LG members, does anyone know about European 32W preheat circline fluorescent fixtures experiencing frequent ballast failures?

Here are the documents that show the specifications for the lamps I discussed:

https://www.scribd.com/document/110155293/Westinghouse-Guide-to-Fluorescent-Lamps-Brochure-1979

https://www.lighting.philips.com/api/assets/v1/file/PhilipsLighting/content/fp927982284036-pss-global/Localized_commercial_leaflet_927982284036_en_AA.pdf

Nope no failures so far. Our 32W lamps run on dedicated Knobel 32W/C ballasts. Some other chokes like those from H.Leuenberger and Tridonic are also listing T8 30W and 2x15W Tandem beside the 32W rating.
In the office of a friend there are some TLD Eco 32W/840 running on ckoke ballasts and none of them failed. In general choke ballasts here are extremely robust. The only weak types are those capacitive (lag) ones with a capacitor connected in series whose often loose their capacity during their life and the tubes have some trouble to start.

I also tried some Philips TL-D Eco 32W tubes in one of my 1940s North American 2 lamp 40W T12 preheat fluorescent tube shoplight fixture and they seemed to heat up the ballast quite significantly. It was only for a short test. The arc voltage of those tubes appeared to get very close to that of North American 4 foot 34W T12 tubes that have been known to destroy older ballasts in North America. The fixture I used had a 2 lamp lead-lag autotransformer ballast. Another possibility for older North American ballasts to have such tighter current tolerances was due to many ballasts being enclosed in tar-filled metal casings intended to quiet ballast hum and due to the tar’s black color, it might cause problems for ballast heat dissipation and thus cause runaway overheating of the ballasts. In many of those cases, tar would often leak out of those ballasts.

I have never seen a 32w circline fitting here installed with a 40w ballast, and those fittings are/were very common here. They almost always have a dedicated 32w ballast with maybe the odd one with a 30w ballast.

Because of the fact that many North American 4 foot F40T12 fluorescent tube fixtures have often experienced frequent ballast failures from running 4 foot F34T12 fluorescent tubes, I find the design of many European 32W preheat circline fluorescent fixtures to be very concerning to me for the following reasons:

Many of these fixtures often use 4 foot F40T12 and/or F36T8 preheat fluorescent ballasts.

do you have a source on that?

as per AL_M's comment I cant recall ever really seeing that be a thing, 99% of the 50Hz land 32W Circline fixtures I have studied  always had 30W T8 ballasts or proper dedicated 32W Circline chokes

Here are some examples of some European specification 32W circline preheat fluorescent fixtures that actually use 4 foot 36W T8 preheat ballasts although some of these fixtures are probably used outside Europe but in other countries where the standard voltage is between 220V and 240V and where the frequency is 50Hz:

https://www.lighting-gallery.net/gallery/displayimage.php?pid=141362&fullsize=1


https://images.app.goo.gl/3LhJCKQEmdztN8ek6

https://www.carousell.sg/p/kitchen-bedroom-32w-circular-fluorescent-tube-ceiling-hamburger-light-with-good-quality-ballast-not-led-very-hard-to-get-now-brand-new-1102826282/

These are some examples of some European specification 32W circline preheat fluorescent fixtures with 4 foot 36W T8 preheat ballasts, but they are mostly outside of Europe, but they are found in countries where the standard mains voltage is between 220V and 240V and the frequency is 50Hz.