While doing some research on Japan’s HID lighting systems, I have noticed that one of the unique aspects is the fact that there were some dedicated dimmable mercury vapor lamps that would be designed for use on dedicated dimmable mercury vapor ballasts. Some of these dimmable mercury vapor ballasts had a built in timer and others required a remote relay. These ballasts were often made in either 200V reactor versions or 200V CWA versions. Additionally, Japanese dimmable mercury vapor lamps had the letter “D” as part of the ordering code such as “HF400X•D” to denote that they were dimmable and designed for use on the dedicated dimmable mercury vapor ballasts.

Examples of dimmable Japanese mercury vapor ballasts include the following part numbers:

Toshiba 4HS-2011DHW (dimmable CWA ballast for 400W mercury vapor lamps requiring remote relay)

Toshiba 4HC-205TDH (dimmable reactor ballast for 400W mercury vapor lamps with built in timer)

Toshiba 4HS-203TDH (dimmable CWA ballast for 400W mercury vapor lamps with built in timer)

Iwasaki H4CD2A50

Iwasaki H4CD2B50

Iwasaki H4RD2A50

Iwasaki H4RD2B50

Iwasaki H4RDT2A50

Iwasaki H4RDT2B50

Iwasaki “CD” ballasts are dimmable reactor ballasts requiring remote relays

Iwasaki “RD” ballasts are dimmable CWA ballasts requiring remote relays

Iwasaki “CDT” ballasts are dimmable reactor ballasts with built in timers

Iwasaki “RDT” ballasts are dimmable CWA ballasts with built in timers

Source for Toshiba ballasts:

Toshiba 1992-1993 Catalog page 1050:

https://page3.cextension.jp/c1091/book/index.html#target/page_no=1085

Sources for Iwasaki ballasts:

https://www.akaricenter.com/mame/mame_suigin_anteiki.htm

Iwasaki 2019 catalog page 1446:

https://iwasaki.icata.net/iportal/CatalogViewInterfaceStartUpAction.do?method=startUpByCatalogCategory&mode=PAGE&catalogCategoryId=5165700000&catalogId=15656010000&pageGroupId=&volumeID=IWD00001&keyword=&categoryID=&sortKey=&sortOrder=&designID=SPIWDD001&designConfirmFlg=

I wonder why Japan developed dimmable mercury vapor lamps and ballasts and why other countries did not develop such lighting systems.

Well Japanese seems to like mercury lighting for whatever reason while in the most of the world (probably except Nordics like Finland or Sweden where it is loved too) it is considered obsolete and at EOL and not worth any progress or further refinements.

Also usual arguments apply of energy cost saved vs increased ballast price/maintenance price/extra wiring/programming/special lamps required, all that extra hassles .

I was aware that Japan’s dominance of mercury vapor lighting was largely due to the eyes of Japanese people being better adapted to high color temperature light sources. It certainly is so interesting and unique whenever dimmable mercury vapor lamps and ballasts were developed because most countries seemed to have moved on to metal halide and high pressure sodium lighting due to those lamps having better efficiency while Japan largely had no need to upgrade most existing mercury vapor installations due to cheap electricity being sourced from nuclear fission power plants for many decades. Due to the Minamata Convention banning mercury vapor lamps in Japan in 2020, Japan’s reign of mercury vapor lighting dominance has largely come to an end.

The cultural and physiological factors, like comfort with high color temperatures, and the reliable nuclear power backing it all, really gave those systems a long life. The Minamata Convention kind of forced the shift, but it’s wild to think how long mercury vapor held on there while everywhere else phased it out. Definitely the end of an era

Japan is also well known for having an impressive selection of high pressure sodium and metal halide retrofit lamps designed to run on existing mercury vapor ballasts that were available in a wide range of wattages. These include standard high pressure sodium retrofit lamps in clear or coated finishes, 60 CRI high pressure sodium retrofit lamps in clear or coated finishes, 85 CRI high pressure sodium retrofit lamps in clear or coated finishes, twin arc high pressure sodium retrofit lamps in clear or coated finishes, standard high pressure sodium retrofit reflector lamps, 60 CRI high pressure sodium retrofit reflector lamps, quartz metal halide retrofit lamps ranging from 3700K-6000K in clear or coated finishes, ceramic metal halide retrofit lamps ranging from 3500K-4200K in clear or coated finishes, colored quartz metal halide retrofit lamps, and even twin arc mercury vapor lamps in coated versions. I just find it interesting that Japan has also been considered the HID retrofit lamp capital of the world. Upgrading to newer HID lamp technologies from mercury vapor has simple as replacing a lamp under most circumstances. I also had read that there were dedicated high pressure sodium lamp and ballast systems in use, but standard dedicated ballast high pressure sodium lamps had largely fallen out of favor due to the prevalence of high pressure sodium retrofit lamps designed for mercury vapor ballasts. There were also quite a few 85 CRI high pressure sodium lamps that required dedicated ballasts that happened to be manufactured there until recently. Just knowing these unique characteristics about Japan’s HID lighting systems is enough for me to consider Japan to be my favorite country to collect HID lighting from. In addition to those retrofit lamp technologies also being present, I just also find the dimmable mercury vapor lamps and ballasts quite interesting too.