"Dave" wrote in message
...
Our Triton electric shower trips the mcb after about 3 minutes use. (Fed
via a
combined mcb and rcb). The shower is about 12 months old and been working
fine
until now. I have no way of measuring the actual current. The mcb casing
is
quite warm so I guess real overcurrent is the problem - rather than a
fault in
the in mcb? There is no sign of air in the water supply. Is the above a
typical
failure mode for an electric shower - is it about to go BANG! The cable
and
double-pole ceiling switch are the only other things in the circuit.
Wonder
when the guarantee is up (sigh) :-)
Thanks

Hi Dave,

It sounds like a tired MCB with all the work it's been doing. Check that
all the connections are tightened fully and that all the cable isn't damaged
or squeezed to tightly anywhere. If that checks out OK, then try upping to
the MCB to the next one up in Amperage and see how that goes. It could just
be that you're working that breaker at its full load capacity every time you
use the shower.


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"Dave" wrote in message
...
Our Triton electric shower trips the mcb after about 3 minutes use. (Fed
via a
combined mcb and rcb). The shower is about 12 months old and been working
fine
until now. I have no way of measuring the actual current. The mcb casing
is
quite warm so I guess real overcurrent is the problem - rather than a
fault in
the in mcb? There is no sign of air in the water supply. Is the above a
typical
failure mode for an electric shower - is it about to go BANG! The cable
and
double-pole ceiling switch are the only other things in the circuit.
Wonder
when the guarantee is up (sigh) :-)

what's the MCB rate at ?
how many kilowatts is the shower ?

"Dave" wrote in message
...

what's the MCB rate at ?
how many kilowatts is the shower ?

It's marker B40 - and shower is 9.6kW. The booklet that came with it says
use
mcb 40/45A.

MCB rating is right on the limit (9.6Kw = 40Amps)

Think I've found the trouble though. The copper link that feeds into
the mcb has cracked through but was still making some sort of contact. The
heat
generated has melted some mcb case (!) All is isolated now and I'm off to
get
some new parts tomorrow. I think the copper link cracked as it was folded
at
quite an angle there.

That usually means the MCB wasn't attached to the DIN rail
properly.
You need to look at the cable, it should be 10mm with
a 45Amp MCB
While shopping buy an RCD if you haven't already got one.