'Safe Zone' created by 'current using equipment' ??

[JohnW2]

Although we realise that mirrors and showers etc do not fit into the zone conditions rules nicely I think that, for practical purposes we only decide to treat that object as a point of utilisation in a similar manner, almost no one will make them exceed 50mm deep or amoured/conduit ...

Again, you may be the only person who has really understood the reason I started this thread - namely because I feel that the regulation in question is unsatisfactory (in relation to the issue we've been discussing) and really needs to be revised/improved.

As I see it, with "the letter of the regulation" as it currently is,there are only two possibilities:

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1... IF (despite the actual meaning of "a point") a large wall-mounted current-using item (like an illuminated mirror) is intended/'deemed' to qualify as "a point", with dimensions equal to those of the item (it surely is not an "accessory" or "switchgear",, then the current reg would create 'permitted zones' (for shallow-buried cables) that were so large as to defeat the (presumed) point of the regulation.​

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2... On the other hand, IF the item is not intended/deemed to qualify as "a point", then (unless some other electrical items create permitted zones) there in nowhere on the wall where one is permitted to bury 'unprotected' cables <50mm below the surface, meaning that any shallow-buried cables on that wall would have to have earthed metallic covering or be in metal conduit etc.​

I would suggest that neither of those possibilities is satisfactory and, in the case of (2),as you say, I imagine that most people would simpoly ignore it, leaving it unclear to any third party as to where they might have buried cables.

My conclusion, it is a fudge that we must use to let the mirror/shower etc create the dimension of zone decision, ....

That's my (1) above - and, as I say, it would mean that the reg served very little useful purpose, since it would leave a 'man with a drill' with little guidance as to where he/she could most safely penetrate the wall.

... unless someone has a better idea that has a chance of universal acceptance.

I've made my suggestion as to how the reg could be revised so as to be useful (based on centre point of visible object),but I doubt that will ever happen.

We have no idea where a backbox might be unless the mirror is merely hung up like a picture and from backbox to mirror is a length of flex in a void behind such mirror, if it is fixed in position we cant be expecting Joe Bloggs to lift the mirror away from the wall to take a peek.

Exactly.

.... for a mirror on a wall, no such luck, the whole mirror needs to be treated like a point even if we declare the mirror etc not to actually be a point by definitions. What else can we reasonably do?

See above. With the reg as it is, we are simply between the devil and the deep blue sea- a choice between a situation (per what you're saying) which would mean that the reg would achieve very little and a situation in which most people would probably ignore it - neither of which does much in terms of what one assumes to be the "raison d'etre" of the regulation!

Kind Regards, John

 

[JohnW2]

nobody is suggesting an installer fitting a cable where it should not be. Once we establish where it is actually allowed to be then we hope it will be and accordingly others will miss damage to it

Quite so - and, although there seems to have been a failure to understand this, that was the reason I started this thread!

 

[ebee]

So what do we do?

Well I will tell you what I do (used to do) with a shower.
Well I treat the shower heater unit as if it were a point just like a socket.
I consider the shower dimensions to create a zone just like a socket would.
I think it is the most reasonable thing to do.
Ok it`s a lot bigger than a socket and bathroom walls are often quite small however I feel justified.
I do endeavour to further restrict that zone to (or near to) the area where the connection is made inside the shower to determine the "ideal" zone boundaries as it can be thought quite reasonable that someone might have read the instruction manual including a diagram to determine the place where connection occurs (or might just happen to be competent enough to have actually removed the cover to actually take a peek - but I can not take that as a given).

However, with a mirror, OK it could be small or not massively big so again. in some circumstances it might be reasonable - ish to apply the same ethos.
However, it could quite easily be a large-ish mirror on a small-ish wall, so yes we could sometimes consider utilising the same logic but that is where the idea starts to fall apart.

 

[JohnW2]

So what do we do? ... Well I will tell you what I do (used to do) with a shower.

Fair enough, but as I've said before, I think a shower is small enough for it to be reasonable to treat it just as one would, say, a socket - so I totally agree with what you go on to say (except that you don't need to consider a socket as "a point", since you can treat it, per the reg, as an "accessory"!) ....

Well I treat the shower heater unit as if it were a point just like a socket. .... I consider the shower dimensions to create a zone just like a socket would.
I think it is the most reasonable thing to do. ... Ok it`s a lot bigger than a socket and bathroom walls are often quite small however I feel justified.

Indeed, as I've said. As I've also said before (and you go on to say), it's when the object gets appreciably larger than a shower that issues arise with that approach. As you say ....

However, with a mirror, .... it could quite easily be a large-ish mirror on a small-ish wall, so yes we could sometimes consider utilising the same logic but that is where the idea starts to fall apart.

Quite so - but that begs the question of what would you do (and what the regs would permit you to do) if it were, say, "a large mirror on a small wall" ?? I imagine that the answer can probably be deduced (or, at least suspected) by your going on to say ...

... I do endeavour to further restrict that zone to (or near to) the area where the connection is made inside the shower to determine the "ideal" zone boundaries ....

... and that takes us back to what I've said several times, that there are two sides to this - the viewpoint of the person installing the cable and that of 'a man with a drill', who would like useful guidance as to where the 'dangerous zones'[ on the wall were.

For the person installing the cable,the 'most sensible' thing they can do, and what I imagine most electricians would do, would be, as they would with an accessory, install cables, horizontally or vertically, in at least approximate alignment with where the cable exits the wall and enters the item. Given the regs as they are, that's really all ('the best') that an electrician (or other 'installer'!) can do.​

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However, since the regs do not require that it be done like that, the man with a drill cannot safely assume that the cables will have been installed in that 'sensible' fashion, and therefore may have to consider a large proportion of the wall as representing 'dangerous zones' - which will really not help him much!​

If, in a fashion such as I suggested, the reg defined 'permitted zones' of modest size in this situation, then the man with a drill would have much more useful guidance.

Kind Regards, John

 

[ebee]

(except that you don't need to consider a socket as "a point", since you can treat it, per the reg, as an "accessory"

As a "Point of utilisation" as such a socket, lampholder type light fitting, etc. I know the NICEICs own forms for Periodics used to ask for this number whareas the model forms (IET/IEE) didn`t, it did cause some confusion by some inspectors listing a twin socket as two points rather than as just one, then you`d get someone asking if two adjacent single sockets was one point or two points, well the answer is two points even if they stand together on a dual (not twin) back box.

Mind you it is one example of a simple word having differing meanings to different folks or in different disciplines, you might end up using a definition that has a listing of do and don't that is half the volume of the regs book itself. A bloke I knew often referred to points on cars as the spark plug gap but everyone else I knew used the term for the contact breaker. Yep - depends upon the context in which you use a word or a phrase methinks.

When you use a term it can take quite some defining at times in order to get a consensus, by which time those reading it as per context have fallen asleep

 

[JohnW2]

As a "Point of utilisation" as such a socket, lampholder type light fitting, etc.

Yes, you could consider a socket etc. as being"a point of utilisation", but there's no need to do so, since the reg lso applies to "accessories" (and defines the 'permitted zones' in relation to the dimentsions of the accessory, not of any "point(s)". As you go on to illustrate, when you write ...

I know the NICEICs own forms for Periodics used to ask for this number whareas the model forms (IET/IEE) didn`t, it did cause some confusion by some inspectors listing a twin socket as two points rather than as just one, then you`d get someone asking if two adjacent single sockets was one point or two points, well the answer is two points even if they stand together on a dual (not twin) back box.

... if you consider sockets as "points", that merely results in potential confusion the situation, whereas everything is totally clear and straightforward if one regards them as accessories!

Mind you it is one example of a simple word having differing meanings to different folks or in different disciplines,...

As I've said, in the context of the reg we are discussion, a problem with regarding something as "a point" there is a problem in knowing what is regarded as being its dimensions, hence the dimensions of 'permitted zones'.

Having said that, to my extreme surprise, I find that one of the (very many) definitions of "point" in the Cambridge Dictionary is:

a socket to which a wire from a piece of electrical equipment is connected in order to supply it with electricity or a radio, television, or other signal

.. and I really don't know what to say about that

Kind Regards, John

 

[ebee]

That is perhaps the whole point of it being a point if I may point that out to you John, .
Actually the NICEIC number of points info when you can see that they clearly mean that one twin socket is one point yet two outlets but two single adjacent sockets is two points, I think in truth that info was probably a very good idea originally as if we were to get the chance of reading a previous EICR (or the EIC) to compare and give a hint that some sockets might have been added (that is on the extremely rare occasion that one exists and you get to see it. Evidence of alterations/additions sometimes leads to another clue when fault finding.

By the way, how do we verify points on a railway track?

 

[JohnW2]

That is perhaps the whole point of it being a point if I may point that out to you John, .
Actually the NICEIC number of points info when you can see that they clearly mean that one twin socket is one point yet two outlets but two single adjacent sockets is two points,

I think this is probably somewhat confusing the issue In order to create 'permitted zones' (per 522.6.202) it is necessary for the "point, accessory or switchgear" to have known and visible dimensions. That's straightforward enough for an accessory (or item of switchgear) but, I would suggest, far less so for a "point".

Yes, two (horizontally) adjacent single sockets will create zones with a greater 'width' (but the same 'height') as would a double socket, but that';s because two adjacent single sockets are, together, wider than one double socket - not because they represent "two points".

By the way, how do we verify points on a railway track?

... or the points of a pair of scissors/whatever, or the point of an argument, or the point of doing something, or a point in time, or a point in a game of tennis, or a fielder position in cricket, or a font of a particular number of points, or a point jutting out from the coastline, or a full stop, ... etc. etc.

We are definitely talking about "a word of many meanings"

Kind Regards, John

 

[morqthana]

Having said that, to my extreme surprise, I find that one of the (very many) definitions of "point" in the Cambridge Dictionary is:

a socket to which a wire from a piece of electrical equipment is connected in order to supply it with electricity or a radio, television, or other signal

.. and I really don't know what to say about that

That's what my parents called sockets.

 

[morqthana]

View attachment 340357

If that were a large cooker hood its footprint could be 2m wide and 1m high.

 

[JohnW2]

If that were a large cooker hood its footprint could be 2m wide and 1m high.

Exactly, which is why it would be of minimal value to the man with a drill - and hence why I find it hard to believe that such was the intended interpretation of the reg!.

 

[ebee]

Yep. Good example.
So, what do we do?

 

[JohnW2]

Yep. Good example. .... So, what do we do?

As has been implied by the discussion, there is a definite limit to what can be done.

As I have said, the 'safest' approach (and conceivably {although I doubt it} the intended interpretation of the reg) would be 1to say that a large item of current-using equipment does NOT qualify as a 'point, accessory or switchgear), in which case, unless something else on the wall created 'permitted zones' it would not be permissible to bury a cable (<50mm) anywhere in the wall unless it had an earthed metal covering or was in metal conduit etc.

Other than that, I don't think there is anything that one can do which is particularly useful (to 'a man with a drill'). I cannot think of anything one could do (other than 'providing documentation') which would offer particularly useful guidance to someone who wished to penetrate the wall - as EFLI said in the initial discussion such a person would presumably have to consider as 'dangerous' those zones which were defined by the height and width of the equipment - which, as has been said, could represent 'most of the wall'.

I've offered my personal suggestion as to how a useful reg could be written, but I doubt that will ever happen.

There is another issue that we haven't really discussed, and about which no electrical regulations, nor any electrician, can do anything about ...

... even if cables are buries, compliantly, in the permitted zones (say, ones created by a visible electrical accessory) currently defined by BS7671, there is clearly nothing that BS7671 (or an electrician) can do to prevent someone (householder, builder, kitchen fitter, decorator or whoever) subsequently installing or doing something 'non-electrical' which renders 'no longer visible' the item that created those 'permitted zones'. Hence, unless the wall is totally 'bare', it is never possible for the person with drill to be certain that the wall does not contain zones where buried cables would be permitted by the regs.

EFLI would probably say that, because of that, the only 'solution' is 'common sense' - but, unfortunately, that really is nothing more then 'guessing, hoping and praying'. 'Cable detectors'can obviously help, but are far from infallible.

Kind Regards, John