Since most fluorescent starters used today in almost every country in the world use the 2 pin twist lock P21 base, I have been wondering why the 2 pin twist lock P21 base was chosen as the global standard for fluorescent starters rather than other bases like E26, E27, B22, or something else.
Oddly enough, I was only able to find out that standard fluorescent starters had the P21 base whenever I looked at specification sheets for Japanese fluorescent starters that had the same standard 2 pin twist lock base used on almost every fluorescent starter in the world.
Here is a Japanese fluorescent starter specification sheet that specifically mentions the P21 base on global standard fluorescent starters:
https://elpadirect.com/smartphone/detail.html?id=000000003775Feel free to write any info on why that fluorescent starter base was chosen as the global standard for fluorescent starters in general.