wrote in message
oups.com...
It requires fitting and wiring by a competent person. Sorry to say it
but
the fact that you have to ask demonstrates that you are not qualified
to.

This is self evident - but having asked the question and gathered the
necessary information then one is then better qualified than before -
which is also self evident.


I just installed a new Gainsborough 9.5kw shower in my new bathroom -
following the useful instructions on the packet and having studied
postings on this group. Nobody dead yet but we are all lovely and
clean!
As a matter of interest does anyone know what the showerer would
experience if there was a major failure sufficient to trip the RCD?

A shower of sparks ??? !!!

Kev

On 11 Jun 2005 10:57:39 -0700, wrote:

[snip]

As a matter of interest does anyone know what the showerer would
experience if there was a major failure sufficient to trip the RCD?

It depends on the path the leakage current took.
All the electric showers I have seen use a metal heating chamber that
is *well* bonded to the earth wire, and the metal pipework is probably
well earthed too, thus, if the failure occurred inside the shower unit
they would probably just experience a 'click' noise followed by either
no water or cold water, depending on the unit. If for some hideously
unfortunate reason the current went through the shower head, or
through their body by some other means [maybe faulty control
switches], RCDs aren't required to trip before 0.4 seconds at or even
way _above_ their rated tripping current, so I wouldn't want to be
them particularly.

--
I think computer viruses should count as life. I think it
says something about human nature that the only form of
life we have created so far is purely destructive. We've
created life in our own image. - Stephen Hawking

Chipmunk wrote:

....... RCDs aren't required to trip before 0.4 seconds at or even
way _above_ their rated tripping current, so I wouldn't want to be
them particularly.


(All together now) Oh Yes They Are ;-)

According to the On-Site Guide, itself referring to Reg 713-13-01, the
specs for an RCD spec'd to provide supplementary protection and with a
nominal operating current of 30mA or less - and it's overwhelmingly
likely that this is the spec a dedicated RCD will be made to - are that
it opens in under 40ms - that's just two full mains cycles - for a
current of 5 times nominal. And the trip times for other RCDs are to
trip within 300ms, rather'n 400ms.

Nevertheless, your main point stands - sloppy installation practices
can't be justified with an 'it's OK, it's all on an RCD which will pop
if anything goes wrong'. Apart from anything else, RCDs don't mind at
all if you cause an L to N flow from one hand to the other...

Stefek

On Sat, 11 Jun 2005 22:19:33 +0100, Stefek Zaba
wrote:

Chipmunk wrote:

....... RCDs aren't required to trip before 0.4 seconds at or even
way _above_ their rated tripping current, so I wouldn't want to be
them particularly.


(All together now) Oh Yes They Are ;-)

According to the On-Site Guide, itself referring to Reg 713-13-01, the
specs for an RCD spec'd to provide supplementary protection and with a
nominal operating current of 30mA or less - and it's overwhelmingly
likely that this is the spec a dedicated RCD will be made to - are that
it opens in under 40ms - that's just two full mains cycles - for a
current of 5 times nominal. And the trip times for other RCDs are to
trip within 300ms, rather'n 400ms.

Nevertheless, your main point stands - sloppy installation practices
can't be justified with an 'it's OK, it's all on an RCD which will pop
if anything goes wrong'. Apart from anything else, RCDs don't mind at
all if you cause an L to N flow from one hand to the other...

Stefek

I stand corrected, eek I misplaced the decimal point. I plead ...
umm.. braincell recycling due to being out of the UK for 5 years:-)

Yes, the 40ms for 'circuits supplying portable appliances' and 300ms
for 'fixed appliances and wiring' sounds familiar.

Still, even 10mA leakage if I was in a shower would scare me.

--
I think computer viruses should count as life. I think it
says something about human nature that the only form of
life we have created so far is purely destructive. We've
created life in our own image. - Stephen Hawking

In message ,
Chipmunk wrote:

RCDs aren't required to trip before 0.4 seconds at or even way _above_
their rated tripping current, so I wouldn't want to be them
particularly.


30mA RCDs used as supplementary protection (the usual domestic sort) are
required to trip in 0.04 seconds (40ms) at 5xrated current. See for
example BS7671 412-06-02(ii). Although not specified in BS7671 I believe
that the BS/EN for RCDs determines that the trip time at rated current
should be no more than 200ms (0.2s).

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... --T-A+G-L-I+N-E--+M-E-A+S-U-R+I-N-G+--G-A+U-G-E--

Chipmunk wrote:

Yes, the 40ms for 'circuits supplying portable appliances' and 300ms
for 'fixed appliances and wiring' sounds familiar.

I think you may be thinking of the required EEBADs disconnection times
of under 0.4 for portabel appliances and 5 seconds for fixed. RCDs are
supposed to be a whole lot quicker (unless time delayed!)


--
Cheers,

John.

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