"Tough Guy no. 1265" wrote in message
news
On Tue, 15 Dec 2015 01:46:37 -0000, John Rumm
wrote:

On 14/12/2015 18:23, Tough Guy no. 1265 wrote:
On Mon, 14 Dec 2015 18:05:50 -0000, John Rumm
wrote:

On 14/12/2015 16:01, Tough Guy no. 1265 wrote:
On Mon, 14 Dec 2015 11:07:19 -0000, John Rumm
wrote:

On 12/12/2015 12:52, ARW wrote:
"Mike Humphrey" wrote in message
o.uk...
Graham. wrote:
On Fri, 11 Dec 2015 23:29:35 -0000, "Tough Guy no. 1265"

wrote:

Had a look around on t'internet, seems to be no real reason to
have
a shower cord in the bathroom. Why does it need to be switched
off
any more than any other appliance? Apart from maintainence once
a
decade, in which case you pull the fuse in the fusebox.

Doesn't have to be a pullcord, can be a dolly switch outside the
bathroom.
I don't trust pullcord switches, even if they have a mechanical
tell-tail, so I would always isolate upstream as well.

Every appliance needs an isolator, and an isolator must isolate all
live
conductors - that is both line and neutral.

On a TN system there is no requirement to isolate the neutral and a
single pole MCB is allowed to be the isolator.

Indeed, although if you only have single pole switching, then you
need
to have a suitable place to allow disconnection of the neutral as
well
(537.2.1.7).

One could do this at the CU, but it seems preferable to have another
place to do that.

Why would you need to remove a 0V wire? They don't hurt when you
touch
them.

Because in reality it won't be 0V. Short it to earth, and you will most
likely trip the RCD potentially de-energising other circuits.

Then the RCD is unfit for purpose. It's supposed to detect live to
ground, not neutral to ground.

No, its supposed to detect an imbalance between current flow in Line and
Neutral.

No, that's what it does, in an effort to detect stray current to earth,
it's the easy option and as has just been pointed out a complete and utter
failure.

Anyway, if what you said was true,

It is.

it could happen with any electrical
item, as most things only have a live switched off.

No, because switching something off by disconnection of the live via a
switch does not also connect the Neutral to Earth.

It leaves the neutral available.

(its also good practice IMHO have local isolation for showers, since
this avoids the whole issue of needing to lock our the MCB, and gives
the consumer confidence that they have a way of turning it off in the
case of an emergency)

Lock? You switch it off (in the VERY unlikely event you're working on
repairing or replacing the shower). If you have a wife or kids, tell
them to leave it off, not that they'd have a reason to turn it on if
they weren't trying to have a shower and failing (which is impossible
since you're in there fixing it).

If you were fixing the shower, I could understand their temptation to
turn it back on!

It's best not to electrocute someone who's doing you a favour.

But they would be doing themselves favour...

They'd not get a working shower.

Corse they would when your corpse is removed and
they get someone else to fix it.