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In article ,
(Stephen) writes:
Hope someone can advise.

The fuse on my immersion heater keeps blowing. It is on its own 15A
circuit. The fuse doesn't blow immediately but after one or two days.
I have replaced the fuse three times and wired around the timer to
eliminate it as the cause.

Could it be anything other than the immersion heater causing the blown
fuse ?

The element could have shorted to the casing, causing it to draw
more current. This will make the fuse carrier very hot (and the
cable quite likely warm too).
If it's an intermittent short such as a cable fault, then the
fuse carrier won't have time to heat up (although it might be
slightly warm just from normal operation of the immersion heater).

This is a handy technique to diagnose an overload current blowing
a fuse verses a fault current (short circuit) blowing a fuse,
but you have to get there immediately after it happens.

--
Andrew Gabriel