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

[JohnW2]

As many of us are aware, in relation to permitted routes for cable buried <50mm deep in walls, 522.6.202 says (in part) ...

522.6.202
A cable installed in a wall or partition at a depth of less than 50 mm from a surface of the wall or partition shall:
......... Where the cable is connected to a point, accessory or switchgear on any surface of the wall or partition, the cable may be installed in a zone either horizontally or vertically, to the point, accessory or switchgear.

In a recent thread, it was suggested that, in this context, items of 'current-using equipment' (including large ones - illuminated mirrors and TVs, fixed to walls, were mentioned as examples) qualify as a "point, accessory or switchgear to which cables are connected" and therefore create (potentially enormous) zones in which buried cables may be buried ('Safe Zones').

I have to say that it has never even occurred to me that 'current-using-equipment' (particularly large items) can create 'Safe Zones' in this fashion, and I do find it pretty hard to believe that this is the intended interpretation of this regulation.

What do others think?

Kind Regards, John

 

[ericmark]

Not fixed a mirror, buy TV tends to have fixing brackets on which the TV is placed, so not really fixed to wall, it is fixed to a bracket which in turn fixed to wall.

And some where there is something which allows the cable to exit the wall, which will remain when the TV is removed, one does not have brushed the width of TV so the cable can exit the wall else where.

So it is the connection unit which is fixed to the wall, be it brushes, or a socket, or a FCU, or even a cooker connection unit which shows where the cable should be running.

I seem to remember some thing about an expensive painting as to defining fixed, nailed to wall is fixed, screwed was not, as clearly designed so it could me moved.

Yes I know we screw the back box to wall, but it then plastered, and one can't remove the back box or wiring without damage.

 

[EFLImpudence]

In a recent thread, it was suggested that, in this context, items of 'current-using equipment' (including large ones - illuminated mirrors and TVs, fixed to walls, were mentioned as examples) qualify as a "point, accessory or switchgear to which cables are connected" and therefore create (potentially enormous) zones in which buried cables may be buried ('Safe Zones').

Is that not the case if one cannot tell where exactly the "point" is?

 

[JohnW2]

Not fixed a mirror, buy TV tends to have fixing brackets on which the TV is placed, so not really fixed to wall, it is fixed to a bracket which in turn fixed to wall.

Fair enough, but there are some TV's (and 'picture walls' etc.) which are pretty comprehensively 'fixed to a wall' - and, in any event, there are plenty of other examples of sizeable items of 'current-using-equipment' which I don;t think anyone could argue are not 'fixed to a wall'- what about wall-hung boilers, for example (as well as the illuminated mirrors, which have already been mentioned)?

So it is the connection unit which is fixed to the wall, be it brushes, or a socket, or a FCU, or even a cooker connection unit which shows where the cable should be running.

That's what I have always assumed, and it seems to correspond to some extent with common sense (although the 'connection unit' doesn't serve much value as an indicator of where cable might be if it is hidden from view behind some piece of equipment, like a TV). However, as I said, this is not what was being suggested in the other recent thread.

 

[plugwash]

Point (in wiring) A termination of the fixed wiring intended for the connection of current-using equipment.

For an appliance connected to an outlet box by a non-fixed cable, this seems pretty obvious to me, the outlet box is the point, the appliance itself is irrelevant.

But what about appliances that are fixed to the wall with the fixed wiring terminated directly? I would agree that interpreting the whole appliance as the "point" is overly broad, but not allowing them to be fed by concealed cabling at all would be overly restrictive and in no way consistent with actual practice.

So to me, the only reasonable interpretation for appliances fed directly for fixed wiring is that the "point" is where the cable emerges from the wall.

And yes in some cases this means it may be necessary to open the equipment, or even remove it from the wall to determine exactly where the "point" is.

 

[JohnW2]

Is that not the case if one cannot tell where exactly the "point" is?

Well, things like TVs and mirrors are certainly not 'accessories' (it presumably means 'electrical accessories') or 'switchgear' so they could only qualify (in terms of the reg) as 'points' - and if one takes that literally (pedantic?), a point has no finite size, and therefore would create vertical and horizontal 'Safe Zones' of zero width, which would not be very useful !

However, the point is that (witness the fact that most people, although not the regs, talk/think of them as 'safe zones') by allowing large itrems to create large 'zones', many people will regard that as meaning that it is 'safe' to bury cables anywhere in those large zones (which, kin extreme cases, could be most of the wall).

I therefore think it's a flawed concept. When there is a visible accessory, then it's reasonable to suggest that buried cables may well be aligned with it, but if one is talking about large items, the only sensible view is to say that buried cables could be 'almost anywhere' and not promote the idea that there is something 'safe' about burying cables in large areas of wall aligned with the item.

As I've said, I find it very hard to believe that your view corresponds with the intended interpretation of the reg

 

[JohnW2]

For an appliance connected to an outlet box by a non-fixed cable, this seems pretty obvious to me, the outlet box is the point, the appliance itself is irrelevant.

As I've just written, I totally agree - and, as I said, I think we are essentially talking about (electrical) 'accessories.

But what about appliances that are fixed to the wall with the fixed wiring terminated directly? I would agree that interpreting the whole appliance as the "point" is overly broad, ...

Quite so - and that broadness is potentially misleading - since, as I've just written, even though I don't think the regs use the word, many people will probably feel that it is 'safe' to bury cables in a 'zone' created by something.

but not allowing them to be fed by concealed cabling at all would be overly restrictive and in no way consistent with actual practice.

Indeed - which is why I think the whole concept of this ree, 'well-intentioned' though it is, is a bit flawed.

So to me, the only reasonable interpretation for appliances fed directly for fixed wiring is that the "point" is where the cable emerges from the wall.

Yes, but you're then getting close to the point (sorry ) I just made about the literal (pedantic?) interpretation of the reg, since 'the point where the cable emerges from the wall would create very narrow (horizontal and vertical) 'safe zones', too narrow to be of practical value.

And yes in some cases this means it may be necessary to open the equipment, or even remove it from the wall to determine exactly where the "point" is.

... and, as above, one would have to somehow (arbitrarily) define how big that 'point' was deemed to be, otherwise the zones it created would be too narrow to be useful. ... and, in any event, the whole idea is surely that the point/accessory/whatever should be 'normally visible' (i.e. without any dismantling or destruction) - we often point out to people that an accessory (particularly a 'blank plate' do not create 'safe zones' if they are not visible (e.g. 'plastered over')

 

[EFLImpudence]

So - are you now disputing the usage of the words 'point' and 'safe'.
It is unusual for terms in the electrical trade to be less than ideal.



I think you are looking at it the wrong way round.
It is not that someone is burying a cable away from the horizontal or vertical position of a "point"; it is that when your appliance(mirror) is fitted, that point is no longer visible so where might you consider NOT drilling - just in case?

Edit - sorry appliance not accessory.

 

[JohnW2]

So - are you now disputing the usage of the words 'point' and 'safe'.

As I wrote, the word 'safe' is nowhere used by the regs in relation to the permitted zones for buried cables - it is ';everyone else' who seems to have created, and be extensively using, that term.

As I've also written, 'point'; is not really a very satisfactory term in this context, because it does not provide any meaningful indication (let alone definition) of how wide the 'zones' created by that point are.

I think you are looking at it the wrong way round. .... It is not that someone is burying a cable away from the horizontal or vertical position of a "point"; it is that when your appliance(mirror) is fitted, that point is no longer visible .....

What 'point' are you thinking about that is not visible once the appliance/whatever is fitted?

In the previous thread, you were suggesting that the 'zones' created by the appliance were as wide/high as the overall dimensions of the appliance/whatever. Have you changed your view?

 

[EFLImpudence]

What 'point' are you thinking about that is not visible once the appliance/whatever is fitted?

Is that not obvious? The point where the cable is connected.

In the previous thread, you were suggesting that the 'zones' created by the appliance were as wide/high as the overall dimensions of the appliance/whatever. Have you changed your view?

I think you are looking at it the wrong way round.
It is not that someone is burying a cable away from the horizontal or vertical position of a "point"; it is that when your appliance(mirror) is fitted, that point is no longer visible so where might you consider NOT drilling - just in case?

What more can I say?

 

[Murdochcat]

Using a CU as an example, the safe zone is the height and width of the CU

I would say the same is for any fixed load but not plugged in items but I would never run cables on the basis that an appliance would create a safe zone

Common sense suggests the connecting accessory creates the safe zone, and not say a TV, fridge or microwave.

But when did common sense apply to BS 7671

 

[JohnW2]

Using a CU as an example, the safe zone is the height and width of the CU

Agreed - and I have no problem in regarding a CU as an "accessory or switchgear".

I would say the same is for any fixed load but not plugged in items but I would never run cables on the basis that an appliance would create a safe zone

Nor would I, and nor do I think that's what the reg intends. However, I'm not sure what yoiu mean by "you would do the same for any fixed loas but not plugged in".

Common sense suggests the connecting accessory creates the safe zone, and not say a TV, fridge or microwave.

Exactly. As I've said, it had never occurred to me that things like TVs etc. might create 'safe zones' until one of your colleagues recently suggested that they did.

But when did common sense apply to BS 7671

In this particular case, I suspect that the intent of BS7671 does correspond with what you and I regard as common sense - the only issue being the way in which at least one person seems to be interpreting 'a point'.

 

[Murdochcat]

Exactly. As I've said, it had never occurred to me that things like TVs etc. might create 'safe zones' until one of your colleagues recently suggested that they did.

Who said what and in which thread?

 

[JohnW2]

Is that not obvious? The point where the cable is connected.

I'm afraid that it's far from obvious to me.

In the case of an accessory with a faceplate of approx 90 x 90 mm or 90 x 150 mm, the 'widths' of the 'zones' it creates are very clear. However, if we start talking about 'the point where the cable is connected', I haven't a clue as to what that means in terms of the 'widths' of the zones, have you?

In any event, I started this thread since you appeared to be saying that something like a mirror or TV created 'zones' whose dimensions were defined by the overall dimensions of the item/'appliance' concerned. As I asked, has your view about that perhaps changed?

 

[JohnW2]

Who said what and in which thread?

.........

I would say the mirror with a light creates a safe zone for its entire width.

Do you really believe that a mirror with a light counts as a "point, accessory or switchgear", because I don't think I would.

Yes. If not where do you draw the line?

Do you believe that, for example, a massive TV on a wall creates massive safe zones, both horizontally and vertically?

Given that 'safe zone' refers to an area where people think there might be buried cables, how can you not believe that?