Hi SamiT,
as an electrician technician, I can tell you that, if they are sold, they meet the standard... On cable terminals usually there are all the regulatory references (NEMA, VDE, IMQ, etc...)
Only one thing: i saw 2 version of these cables, WITH or WITHOUT ground wire.... buy only those with ground....
All of these are quietly cheap, 'cos they're electrical power cables, not signal ones, so no gold connectors required...
I suppose that if you use a power conditioner, you use a rack. The only hint i can give to you is to keep this cables as short as possible, or at least, don't tie them up in coils.... Tied in this way they can generate magnetic fields, and hence audio noise (Hum) ... try don't buy 3 mt cables, if you need them 50 cm long...
The number of devices you can power depends on the electrical absorption of each of them, you have to make the sum of the individual absorption and the result must not exceed the maximum capacity of the power conditioner
I hope I explained myself, because of my poor English .... if you have any doubts do not hesitate to ask
Massimo