Just checking ... immersion heater spur?

[kai]

Water and space heating (IEE On-site Guide appendix eight):-

Water heaters fitted to storage vessels in excess of 15 litres
capacity, or permanently connected heating appliances forming
part of a comprehensive space heating installation, are to be
supplied from their own separate circuit. Immersion heaters are
to be supplied through a switched-cord-outlet connection unit
complying with BS1363-4. (i.e. a 13amp fuse-connection unit).

Therefore it appears that the present accepted method of wiring
an Immersion Heater, is on it's dedicated circuit ending with a
13amp fuse-connection unit, in full compliance with BS7671:2001
and best practice.

Hope this helps.

 

[plugwash]

you could argue though that the cuircuit up to the FCU was a 16A submain giving a 13A cuircuit to the heater from the FCU and a 3A cuircuit from another FCU to the light

no diversity allowance needed.