Flex size for a couple of sockets on a boat.

[aquaplane]

I'm fitting a couple of extra sockets on Seminole and am trying to size the flex.

Domestic ring mains use 2.5mm2, I Googled it.

Considering the supply is only 16A, and the big users will be a fan heater and a kettle I may be over thinking this.

It looks like 1.5mm2 flex is good enough if it's buried in insulating plaster , which it won't be, and way over spec if it's surface mounted, which it will be.

Should I go with the 1.5mm2 flex for £20 or beef it up to 2.5mm2 for £30 ish just for the peace of mind?

Also while I'm at it, if I want a 12V fag lighter socket in the forecabin, about 8M cable run from the battery, how big a flex should I be looking at for that?

TIA

[sahona]

A hint can be taken from the size of the cable on the appliance you are intending to use.
Also, you will probably not be using flat grey twin and earth. (I hope)
I use stuff that is the same as the lead I take ashore, which is probably the same as fitted to a powerful kettle, not as heavy as is used on an immerser. The dalek on the pontoon will only allow you 16amps anyway.
For the ciggy socket, use the thickest stuff you can lay your hands on that will also fit physically, as you do need big amps at 12 volts if running things like soldering irons and inverters.