Re Shower

Was called to a job tonight on a 8.5Kw Triton shower that had completly melted on to the wall of an OAPs bathroom.

Cecked the circuit and found that it had been wired into the exsisting ring main circuit upstairs. (2.5mm) cable

It had a bs 4293 rcd at the board and on to 32 amp ring.

My question is why did the RCD no trip as this shower was instaled 12 years ago or Mcb trip due to load.

Was called to a job tonight on a 8.5Kw Triton shower that had completly melted on to the wall of an OAPs bathroom. Cecked the circuit and found that it had been wired into the exsisting ring main circuit upstairs. (2.5mm) cable

It had a bs 4293 rcd at the board and on to 32 amp ring.

My question is why did the RCD no trip as this shower was instaled 12 years ago or Mcb trip due to load.

Click to expand...

8500 watts is probably the rating @ 240volts? (need to see box to verify exactly?)

8500watts / 230olts = 35.4amps.

8500watts / 230volts = 36.9amps.

so lets say less than 40amps max flowing...

MCB.

32amp MCB will quite happily let 40amps+ go through it without tripping.

(it may buzz a little bit)

& as shower is only in use for say 10mins -15mins typical average duration...

[p.s. I know of 9500watts showers been running on 30amp fuses without blowing.]

RCD.

The RCD will only trip if something is flowing to earth....

If all power is going between live & neutral.. the RCD will be quite happy to stay 'on'.

RING CIRCUIT.

The 2.5mm ring has two parallel cable capable of approx 26/27amps each...

i.e. 52amps could be carried via both legs of the ring without taking a single leg out!

may need to work out actual Volt drop with 2.5mm ring to see a bit better what is happening at the shower? :|

The overheating may be primarily due to a loose connection at the shower!!!!

I was going to say that !!

Can only add that RCD probably didn't trip because there was no fault to earth.

Thanks for the replies. I just could not belive it that someone could connect a shower up like that and the damage it could have done.

Its not the first and it won't be the last I'm afraid.