Electric shower isolation

[ericmark]

It wasn't her kitchen.

She had no more of a "human right" to go into it than you or I have to go into the kitchen (or office) of a hotel or a restaurant where we happen to be staying/dining.

I would agree, however I feel if there is an area of her own house which presented a danger to her with her medical condition we should have been able to prevent her going there.

 

[JohnW2]

They simply man that a plug without a fuse provides effective isolation.

As I said, that's the only interpretation I could think of, but it really makes no sense. As I said/asked, who on earth would plug it back in (to a 'live' socket) after removing the fuse. As we (and Table 53.4) agree unplugging (or otherwise 'disconnecting') something is, in itself, just about the ultimate in 'isolation' - and, as above, anyone in their right mind would unplug equipment (supplied via a plug/socket) before working on it.

Daft it may be, but to be honest I thought it was perfectly normal and sensible to remove a fuse to isolate something that can be plugged in. I usually do it before throwing away a cut off moulded plug and lead for any reason.

So do I, but I wouldn't personally call that 'isolation', would you? "Disabling", perhaps, but I don't really see that 'isolation' is an appropriate word for something not connected to an electrical installation, is it?

'Isolation' and 'taking steps to ensure that the isolation persists' (e.g. by 'labelling' and/or locking an MCB or main switch) are surely two different things? A switch-fuse has recently been mentioned. I would imagine that (even though, surprisingly, such a device does not seem to appear in Table 53.43) switching that off will usually provide adequate isolation. If it can't be locked off, one might then remove the fuse to reduce the risk of anyone re-energising the circuit, but it would still be 'isolated' even if one didn't do that. Just as with the plug (above), if someone were sufficiently daft I suppose thet could switch the switch-fuse back 'on' after removing the fuse (thereby relying totally on the {absence of the} fuse as the sole means of isolation) - but, again, who on earth would do that, and why?

As far as Table 53.4 is concerned, it's perhaps a matter of clarity/words more than anything else. It seems a little odd to include in a list of 'devices for providing isolation', something that only provides isolation by its absence. If they are including fuses in that list, why not also 'cable', since removing/disconnecting cable is another sure method of achieving isolation (by the absence of a connection)?

As regards another recent comment, I'm a little confused by what Table 53.4 says about 'Isolation Switches' (i.e. 'Isolators'). It seems to be saying that, whilst isolators to BS EN 60669-2-4 and BS EN 60947-3 are both suitable for Emergency Switching and Functional Switching, the latter are only suitable for isolation if they bear the specified symbol - which, by implication, means that the former (ones to 60669-2-4) are suitable for isolation even if they do not bear that symbol. Can you make sense of that?

Kind Regards, John

 

[EFLImpudence]

I would agree, however I feel if there is an area of her own house which presented a danger to her with her medical condition we should have been able to prevent her going there.

I suppose it depends whether 'social services' were correct or whether it is just someone saying something.

 

[JohnW2]

I would agree, however I feel if there is an area of her own house which presented a danger to her with her medical condition we should have been able to prevent her going there.

That's common sense. However, unless someone is 'sectioned' (or imprisoned), there is no legal way of restricting what they do in their own home - in the same way that, if you well-meaningly 'confiscated' their knives etc. (without their consent), you would usually technically be guilty of theft, or if you took steps to prevent them leaving the house, you could technically be guilty of 'imprisonment' or somesuch.

Fortunately, those are aspects of the law which are usually ignored, by sensible people and by police/CPS/courts! Social workers are (understandably, given the existence of 'Sunday papers') often far more nervous about application of common sense.

Kind Regards, John

 

[John D v2.0]

As I said/asked, who on earth would plug it back in (to a 'live' socket) after removing the fuse.

A small child? Another member of the household? A customer? Another electrician? A kitchen fitter? The point is even if they do, it's still isolated.

I wouldn't personally call that 'isolation', would you? "Disabling", perhaps, but I don't really see that 'isolation' is an appropriate word for something not connected to an electrical installation, is it?

IdI simply say unplugged with no fuse. BBu either way, there are two ways it can be isolated, by unplugging or by removing the fuse (or both)
The regs don't say which one you would prefer, that's for you to decided based on the situation.

 

[JohnW2]

A small child? Another member of the household? A customer? Another electrician? A kitchen fitter? The point is even if they do, it's still isolated.

That's all true, but I'm still not sure that it relevant in the context of a discussion about 'isolation'. There are any number of things (with fuses in the plugs) that could plugged in by, say, a child with potentially disastrous consequences. Any steps one took to try to prevent that (e.g. removing fuses, to 'disable') would not normally be regarded as 'isolation', would it?

... BBu either way, there are two ways it can be isolated, by unplugging or by removing the fuse (or both) ... The regs don't say which one you would prefer, that's for you to decided based on the situation.

Yes, but if one is think of "either/or" (i.e. your "there are two ways ... that's for you to decide"), and not 'both', then the only situation in which your choice of one of those would be to remove the fuse would be if you intended to plug it back in to a live socket after you had removed the fuse, which I just can't see anyone doing. If you want the added security (against children etc.) of removing the fuse (as well as unplugging), then you will have done both, not 'decided between the two ways'.

Kind Regards, John

 

[ban-all-sheds]

A switch-fuse has recently been mentioned.

Fuse switch, actually.

I would imagine that (even though, surprisingly, such a device does not seem to appear in Table 53.43) switching that off will usually provide adequate isolation. If it can't be locked off, one might then remove the fuse to reduce the risk of anyone re-energising the circuit, but it would still be 'isolated' even if one didn't do that. Just as with the plug (above), if someone were sufficiently daft I suppose thet could switch the switch-fuse back 'on' after removing the fuse (thereby relying totally on the {absence of the} fuse as the sole means of isolation) - but, again, who on earth would do that, and why?

As observed, there are people who might. And if the plug & socket are remote, I guess that removing the fuse provides the equivalent safeguard to locking off.

Talking of which, is it OK to assume that by now, that if it were the case that accessories officially classed as isolators must have provision for locking off, it would have been mentioned by someone?

As far as Table 53.4 is concerned, it's perhaps a matter of clarity/words more than anything else. It seems a little odd to include in a list of 'devices for providing isolation', something that only provides isolation by its absence. If they are including fuses in that list, why not also 'cable', since removing/disconnecting cable is another sure method of achieving isolation (by the absence of a connection)?

'Why' questions about regulations should really be addressed to the authors of the regulations, not to those who have to work to the regulations.

As regards another recent comment, I'm a little confused by what Table 53.4 says about 'Isolation Switches' (i.e. 'Isolators'). It seems to be saying that, whilst isolators to BS EN 60669-2-4 and BS EN 60947-3 are both suitable for Emergency Switching and Functional Switching, the latter are only suitable for isolation if they bear the specified symbol - which, by implication, means that the former (ones to 60669-2-4) are suitable for isolation even if they do not bear that symbol. Can you make sense of that?

At the moment I think I can.

BS EN 60669-2-4 are suitable for on-load isolation full stop.

BS EN 60947-3 are suitable for on-load isolation only if they carry a particular symbol.

It seems to make perfect sense.

In return, I have a question for you.

What is the difference between isolation and functional switching, given that a switch cannot know why it has been operated?

 

[John D v2.0]

I'm not exactly sure of your point.
I guess it's that there are more ways of achieving isolation than things that we'd call an isolator, and it's possible to isolate the same equipment in more than one way at the same time. All of which I agreelet's move on to a new discussion

 

[ban-all-sheds]

My point is what is the difference between isolation and functional switching.

 

[JohnW2]

I guess it's that there are more ways of achieving isolation than things that we'd call an isolator, and it's possible to isolate the same equipment in more than one way at the same time. All of which I agree

No need to 'guess' - that is all clearly true and, I think, non-contentious.

However, as has been implied, there is perhaps need for more clarity about the distinction between 'Isolation', 'Emergency Switching' and 'Functional Switching'. Looking at Table 53.4, most 'devices' other than 'plug pulling' or 'fuse pulling' (neither of which really sound much like 'devices' to me!) are shown to suitable for both 'Emergency Switching' and 'Functional Switching' (which makes sense) and that most of those (plus the 'plug pulling' and 'fuse pulling') are also suitable for 'Isolation'. In fact, it is difficult to imagine how anything (other than 'plug/fuse pulling') that would be acceptable for 'Isolation' wouldn't also be acceptable for the other two 'functions' (albeit perhaps not particularly convenient for functional switching in a few cases), or why something suitable as an 'Emergency Switch' could not be used as a functional one (and, in many cases, vice versa).

Kind Regards, John

 

[ban-all-sheds]

The latter is easy - the device could very well not be engineered to break the load without being damaged. I can see how it could be that in an emergency it could be used, but for functional day-to-day use could not be used repeatedly.

 

[ericmark]

I bag tie rapped over plug, so it needs a pair of snips to remove it. As I found out the hard way, locks can be removed, needing a key or tool simply means people one would hope think twice before re-energising, be it snipping off a tie rap or removing a lock one is aware the item has been isolated rather than unplugged, switched off or tripped. So tie wrapping the plugs cable across the pins of the plug shows it should not be plugged in.

It does not matter if tails in consumer unit dropped, or plug removed, or lock fitted some one can still re-energise. Yes I know insulation tape over the MCB is not accepted, but in real terms anyone who removes the tape could also remove the bracket and lock, so the removal is not an accident. I have seen where two people are working on circuits from the same distribution unit and the wrong circuit was re-energised after work was completed. So yes in a factory you need personal locks and clamps able to take multi-locks.

But the big problem is actually fitting the lock, we had moulded breakers so I ordered the brackets allowing them to be locked off, in a distribution unit mounted horizontal these worked, however with a single unit mounted vertical the power coated lid covered the holes required to mount brackets. Design flaw it may be, but it points out even with best will in the world, locking off is not as easy as one thinks.