xavier wrote:
7KW Shower, 10m cable run. Is 6mm2 OK Please? No tables here, only chairs

Xav

Definitely maybe ;-)

7kW is 30A at 240V (well, 29.2). The OSG's Table 7.1 of Conventional
Circuits gives 39m as the max length for a 6mmsq radial with a 32A Type
B MCB/RCBO, for "broadly all" installation methods including "directly
in a thermally insulating wall", so you look to be OK. However, 7kW
units are falling out of favour, with more power-hungry 8.4kW and
upwards being most widely available. Since cable cost is a small
proportion of the overall job, you'll be better future-proofed running
the circuit in 10mmsq, which would allow a later uprating of the MCB to
40A (45A only for the more restrictive clipped-direct,
embedded-in-plaster, or in conduit/trunking - not the
in-thermally-insulated wall case) allowing a future shower to be rated
up to 9.6kW.

This quick OSG lookup ignores other factors - cable grouping, higher
ambient temps, and so on; nor is it backed by any form of liability
insurance. It's a random collection of bytes apparently written at a
keyboard attached to a machine with the source IP address you'll see in
the headers; if following this advice makes your house burn down or your
visiting US-personal-injury-lawyer-just-using-the-shower fry, hard luck!

Stefek