Dodgy Shower

[ukants]

Could anyone confirm that I'm right to be alarmed about the state of my shower installation (fitted b4 I bought the house):
It's 9.5kW; 6mm cable run about 8 metres
No isolator switch,
No RCD,
and originally on a 30a rewireable fuse (!!!)

Now, I converted the old Wylex rewire fuses to MCBs as soon as I moved in, so it's now on a 32a mcb.

Can anyone tell me if I'm on the right lines thinking that:

#An RCD is a VERY good idea (the CU doesn't have one);
#An isolation switch (double pole?) is a Very good idea (or does the removabe MCB cover this (though not the double pole issue));
#6mm cable is borderline at best (though the regs do allow up to 46a for ref method 1, which is this one);
#The MCB sums don't add up - (9500/230 = 41.3a or 9500/240 = 39.6a) so why is the 32a mcb not tripping? Am I getting away with it because I rarely have the shower on full heat?

Your opinions are appreciated

 

[Adam_151]

Can anyone tell me if I'm on the right lines thinking that:

#An RCD is a VERY good idea (the CU doesn't have one);

Yes, Though strangely enough, not actually required by the regs

#An isolation switch (double pole?) is a Very good idea (or does the removabe MCB cover this (though not the double pole issue));

It needs an isolation switch

#6mm cable is borderline at best (though the regs do allow up to 46a for ref method 1, which is this one);

well I wouldn't install 6mm² for it, but as long as its ref method one all the way along it, and you are sure of this, and its unlikely to change then its not a problem

#The MCB sums don't add up - (9500/230 = 41.3a or 9500/240 = 39.6a) so why is the 32a mcb not tripping? Am I getting away with it because I rarely have the shower on full heat?

Its not the water temperature that affects that, that control just merely adjusts the flow rate to affect the temperature, the reason why is that a 32A breaker doesn't trip at 32.0001A , it'll take 32A*1.15 = 36.8A indefinitly, and will trip at 32A*1.45 = 46.4A withinn an hour (though I suspect its quite a bit faster than an hour), so the reason that it doesn't trip is the shower is not on long enough