Great question — answering as the UphillTech team:
First, I really don't advocate splicing new plugs onto old wires unless you really know what you're doing. Many of these devices likely have UL listings, which help ensure their safety in a residential context, but which also depend on the system as a whole, unmodified. If the device says 110-240VAC and 50/60Hz, then you can simply use a plug converter, no need to splice.
Full answer by Hari: https://diy.stackexchange.com/a/111116 (CC BY-SA 3.0).
Need it done for your business? UphillTech.
