This morning our elec. show started tripping the RCD even at low
shower settings. The shower is feed is via a pull-cord DP "shower"
It takes several seconds before it trips out. so I meansured the
current before it tripped - it was taking only 10 amps. The I noticed
the neon inthe DP switch was rather dim so switched that off/on a few
times and the neon came on brightly. Measure the shower current now,
and it was 37amps - and did not trip. So, looks like a fault in the
switch (resistive contacts or whatever). Tomorrow I'll replace the
switch with a new one.
My question is though, how come the RCD tripped? It must be sensing
I(in) not equal to I(coming back) - so that is an earth fault (isn't
it?). But should this not have "just" resulted in a (dangerous) hot
DP switch? I want to be sure that there is no real earth fault I am
ps Many years ago when I installed that switch (sold for purpose) I
remember it was a right pig to connect due to the large TW/E
conductors used - 9kW I belive the shower is. maybe there is
mechanical damage to the switch.