I'll be honest, I started out thinking this thread was a bit daft, but you're right. I'm not sure where I got the class 2 from because I've just looked and I can't find a double insulated logo on the unit or any mention of device class in the manual. It does state that the filter/pump is 12V and the heater/jets are mains voltage and their peak demand but that's about it.
The manual states "This appliance must be connected to a grounded mains supply socket and a supply cord fitting with a plug and PRCD equipped with a tripping current of 10mA. The appliance with earthing must only be plugged directly into an earthed socket-outlet of the fixed wiring."
Ok, so far so good.
It then says "A qualified electrician shall wire the spa control unit to the household equipotential terminal using a minimum 1.5mm2 solid copper conductor".
I wonder if this is really aimed at other countries where sockets without an earth are still a possibility?
I can't really see your average consumer buying one of these and being expected to crack open the tub electrics, whip out some singles and lugs and start bonding things, so I have no idea what they're on about.
Interesting that they state a minimum CSA for the earth conductor though. I'm pretty sure there are still older installations around that used 2.5mm2 T+E with a 1mm2 earth.
Thankfully, I have a TN-S supply so I'll not give it any further thought and enjoy my hot tub!