For the those adapters, I guess they ar made with almost no focus on safety.
Regarding wire sizez, I dug out an old table from befor calculations (PC) was so much used, the electrician just looked in the table and wired after the standard. Melting fuses was still std. at this time.
Here in Norway this worked well.
You may convert from/to AWG here:
https://www.changpuak.ch/electronics/calc_15a.php
