On Tue, 15 May 2018 14:42:38 +0100, alan_m
wrote:

On 15/05/2018 13:33, Archibald Tarquin Blenkinsopp wrote:

The test is passed if neither the terminals /
terminations, nor the accessible external surface, increase in
temperature by more than 52 degC.

This will be a one off laboratory test and not necessarily
representative of the equivalent same test (operation of a kiln)
repeated over regular period over years.

It's much like the mpg figures that car manufactures publish but then in
small print tell you that they are not real world figures. And, just
look how clean diesel cars are!

An increase of 52C from an ambient of, say, 20C takes the temperature to
72C. I would expect prolonged use at 72C to degrade the performance in a
relatively short time. There may also be a problem of screw terminals
and thermal cycling where the temperature regularly changes by 50C.

Not really a problem to diagnose, yellowing of the surrounding area
should be enough to take any "competent" electrician out of his
bafflement.

My point is, that whatever the hardware in use, if the post is an
accurate record, then the electrician was unfit for purpose.

3kW kilns are sold on the basis that they can be supplied via a 13A
plug, they are not 3kW on a permanent basis, they are reasonably well
insulated anyway.

If the thing was over 3kW even a domestic electrician should be
capable of verifying the fact.


AB