On Sunday, 20 December 2015 17:22:53 UTC, Tim Watts wrote:
On 18/12/15 19:10, Tim Watts wrote:
(Spun off from Chris' thread).

Just noticed my water heater isolator (about 45A load) gets rather warm
after 15-30 mins of operation.

Tightened the terminals - but it seems to be the switch element - the
toggle base gets to perhaps 40-50C by feel. Never noticed before because
I'd never really gone around feeling shower/water isolators under high
sustained loads!

Personally I'd expect a simple switch to be stone cold even under
permanent full load.

Is this reasonable - or time to replace? It's a GET plate - only 6 years
old.

Cheers,

Tim

Well, replaced after some hours with a Crabtree 50A isolator - and after
filling a bath, it is virtually stone cold. The rocker has a hint of
warmth, but you'd be hard pressed to tell.

So the ultimate answer to the subject is "hardly at all".


Apparently according to a sparky I was talking too (not Adam) have have
also been making a mistake of twisting the strands in 10mm2 cable -
something my dad always did....

The terminal should ideally be as full of copper as possible before tightening the screws.
So so, back off the terminal screws fully, twist up the cable if stranded and double over if necessary.

On very large cables, the end should be bound with copper wire.
Rarely seen these days.

The object is to make sure the screw nips the cable rather than going between the strands.