Purpose of shower isolation switch

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.
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wrote:

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.
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Graham.

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Graham. wrote:

Every appliance needs an isolator, and an isolator must isolate all live conductors - that is both line and neutral. It also needs to be either near enough the appliance that someone working on the appliance can see (and stop!) somone going to turn it back on, or it needs a lock. So the fuse in the main fusebox doesn't count - it's single pole and out of sight (in practice with a fuse you can pull the fuse and put it in your pocket, but it's still single pole and technically not an isolator).
For most appliances, they have a plug. Unplugging meets all the requirements for isolation. Appliances that don't have an accessible plug need an isolator switch. That's usually a rocker switch in an appropriate rating mounted next to the appliance. These aren't allowed in a bathroom, though, so you have three choices: a) A pull-cord isolator in the bathroom b) A rocker switch isolator outside the bathroom, but still within sight of someone working on the shower. c) An isolator outside the bathroom that can be locked out.
The default choice seems to be a, though I would argue b is better if possible.
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wrote:

The thick cables can make the choice obvious!
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On a TN system there is no requirement to isolate the neutral and a single pole MCB is allowed to be the isolator.
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Thought so, which is what I've read in some of the legal documents. Yet everybody seems to be fitting these switches.... Unless it's a greenie thing to stop power wastage from the LED/neon on the shower unit?!
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On Sat, 12 Dec 2015 12:52:10 -0000, "ARW"

I didn't know that, and even if I did I wouldn't have been able to convince the bathroom fitters (pre Part P)
They fitted the pullcord isolator three inches away from the existing light pullcord, the obvious place for it was in the corner behind the door when it is open. I got them to move it but it needed a JB to extend the cable which I would rather not have I the loft.
The other thing they insisted upon was a unswitched FCU for the mirror light/shaver socket, even though it was fed from a 6A MCB. They kindly left the 13A fuse in it as supplied.
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So much easier to fit things yourself, the way YOU want them. Why are you not doing so, considering you're in a DIY group?
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So much easier to fit things yourself, the way YOU want them. Why are you not doing so, considering you're in a DIY group?
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Presumably because like with most people he is selective about what he DIYs and what he doesn't.
You are too, you didn't DIY the house you currently occupy. I did mine on a bare block of land.
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I would have done if I thought it would have been cheaper. There's also the problem of mortgages.
After buying the house, I DIY absolutely everything.
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Tough Guy no. 1265 wrote:

I can't resist this: "What's a joist"? (Peter Hucker)
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On 12/12/2015 12:52, ARW wrote:

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

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).
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On 14/12/2015 16:01, Tough Guy no. 1265 wrote:

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.

If you were fixing the shower, I could understand their temptation to turn it back on!
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Then the RCD is unfit for purpose. It's supposed to detect live to ground, not neutral to ground.
Anyway, if what you said was true, it could happen with any electrical item, as most things only have a live switched off.

It's best not to electrocute someone who's doing you a favour.
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In your case it would be an opportunity too good to miss.
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Says the most infamous person in the group.
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On 14/12/2015 18:23, Tough Guy no. 1265 wrote:

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

It is.

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

But they would be doing themselves favour...
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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.

It leaves the neutral available.

They'd not get a working shower.
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