What cable size is for 9kw fryer?

You need someone to apply diversity and do a few calculations for the cable. Anyone who knows the formula, and electrical design, for this would be able to sort it. An electrician with a grasp of the regulations will do. It's not something you can just put your finger in the air and see which way the wind is blowing I'm afraid.

Hi, Before you fit the 1Mtr long flexible cable what's the size of the cable supplying the power to the 'socket' (as you put). You can't just put a big cable connecting the fryer to the, I don't like to use the word you put - socket, and think this will work. The cable supplying the power to the outlet has to be man enough to carry the loading you are going to impose on it, taking into account what else you have connected to this circuit. Best you get someone who knows in to check on this before you do it yourself as the fryer might not be the only thing frying! Depending on the type of premises the appliance is being used in Diversity will differ, a qualified person will do the math's on this and advise you.

As someone said, it's not only about the 1mt. wire from the socket to the fryer. It's about the power admitted into the socket. 9kw it's quite a high power and the usual 13A sockets can support upto 3kw. So DON'T DO THAT! You need a high power socket (usually it has different size) and the circuit behind has to be able to carry 40A. Definitively ,this is not a DIY job, that's something where you need a qualified electrician, otherwise you are in high risk to cause a big damage... (and it is out of the law). P.D. Presumably, we are speaking about a monophasic fryer, being triphasic it is another story. Best Regards. Joserra Veiga