In an earlier contribution to this discussion,
Paul S wrote:

I'm sure this can't be right.
The fused switch that controls my immersion heater is very hot.
I know that some heat will be generated in the cabling as the element
gets hotter, but the switch itself gets too hot to touch.
I've checked the connections inside the switch, and they all seem
secure. Does anyone have any other ideas why this switch is so hot?

In order to generate heat within the switch, the current flowing to the
immersion heater must be meeting some resistance. If the wires are all
secure, the resistance must be coming either from the switch contacts or
from the fuse not being a tight enough fit in the fuse holder. Either way,
if it's got seriously hot, it will never be the same again - and must be
replaced.

Also, is it usual for an immersion heater circuit to be spurred off a
ring main, or should it be on it's own dedicated circuit wired with a
higher rated cable?

I'm not sure about the legality. It's generally considered to be good
practice to have a dedicated circuit - with its own breaker - for the
immersion heater. However, I suspect that a lot *are* spurred of a ring
circuit. Mine certainly is - but I'm not too worried, because my immersion
heater is for emergency use only, with all hot water normally being heated
by gas throughout the year.
--
Cheers,
Set Square
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