Mains smoke and heat detectors

[PBC_1966]

It's not a question of disregard or comprehension - it is nonsense.

You can comply with it by picking whichever part agrees with what you want to do even though other parts may not.

Or you could be certain of complying with it by never using 1.0 sq. mm at all and using 1.5 as a minimum.

So what's the problem?

Clearly the regulation as written was intended to permit 1.0 to be used for something involving lighting. But what? It's ambiguous as to what "lighting circuit" includes, and in the absence of some definition of "power circuit" which says it shall exclude whatever "lighting circuit" means, it's also contradictory since a circuit supplying power to lights is, by definition, a power circuit.

How would you work out what the minimum permitted cable size is supposed to be if you had a circuit feeding one light plus five fans? Or five lights plus one fan? Or three lights and three fans?

 

[EFLImpudence]

You can comply with it by picking whichever part agrees with what you want to do even though other parts may not.

So what's the problem?

The problem is that the parts which restrict what you may want to do are negated by other parts which electrically are no different.

There are no reasons for lesser requirements for a lighting circuit which may have a greater demand than a power circuit nor a definition for either.
Should I want to wire a circuit with a smaller csa than is apparently stated in the first part then I just have to use sheathed or non-sheathed flexible cable rather than sheathed or non-sheathed cable.

In other words any csa of flexible cable may be used subject to normal design characteristics but (presumably other (although it does not say)) cable is subject to minimums without reason.

 

[stillp]

The minima are perhaps without a reason of which you are aware. Does that make them incorrect?

By the way, did any of you who feel the Table is wrong make a comment to that effect during the public consultation?

 

[EFLImpudence]

The minima are perhaps without a reason of which you are aware. Does that make them incorrect?

Yes, unless all the CCC tables are wrong.

By the way, did any of you who feel the Table is wrong make a comment to that effect during the public consultation?

It's not a new table.

 

[stillp]

The minima are perhaps without a reason of which you are aware. Does that make them incorrect?

Yes, unless all the CCC tables are wrong.

By the way, did any of you who feel the Table is wrong make a comment to that effect during the public consultation?

It's not a new table.

Why would it have to be the same as the CCC table?
You had a chance to point out what you felt was wrong with Table 52.3. The draft was available for public comment on all of its provisions, not just the new ones.

 

[EFLImpudence]

Why would it have to be the same as the CCC table?

Why would it not?

You had a chance to point out what you felt was wrong with Table 52.3. The draft was available for public comment on all of its provisions, not just the new ones.

Fair enough.

 

[stillp]

Why would it have to be the same as the CCC table?

Why would it not?

Because it's not about CCC?

 

[EFLImpudence]

What is it about?

 

[PBC_1966]

The minima are perhaps without a reason of which you are aware. Does that make them incorrect?

So what is the reason?

It can't be about the current-carrying capacity of the cables, because (a) that's already covered elsewhere, and (b) it makes no sense when you could easily have a lighting circuit supplying more power than a "power circuit," whatever the latter might actually be (assuming for the moment it means something other a circuit which feeds nothing but lights).

It can't be about voltage-drop on those cables. because that would depend (a) on the length of the cable which isn't mentioned in the table, and (b) on the load which, as noted already, could easily be higher for a circuit feeding lights than for some other circuits feeding other things.

It can't be about mechanical strength and some decision that after all these years they feel something sturdier than 1.0 sq. mm would be a good idea, otherwise 1.5 sq. mm would have been specified as the minimum for everything.

So what exactly is it about?

 

[ban-all-sheds]

BAS, don't tell me you've joined the other clowns who think they can disregard any part of a standard that they don't agree with, or don't understand?

It's not a question of disregard or comprehension - it is nonsense.

 

[ban-all-sheds]

How would you work out what the minimum permitted cable size is supposed to be if you had a circuit feeding one light plus five fans? Or five lights plus one fan? Or three lights and three fans?

Or what about one of these:

Is that a fan, or a light?

And what if I have an incontrovertibly lighting circuit, because it has nothing on it but lights, and I add a shaver socket in the bathroom - do I have to rewire it all in 1.5mm²?

 

[PBC_1966]

Or what about one of these:

Is that a fan, or a light?

Or if the number of lights versus the number of non-lights on the circuit somehow comes into play in what defines a "lighting circuit," is it a fan and four lights?

And what if I have an incontrovertibly lighting circuit, because it has nothing on it but lights, and I add a shaver socket in the bathroom - do I have to rewire it all in 1.5mm²?

But if the incontrovertibly lighting circuit was wired after this regulation was adopted, should it have been done in 1.5 sq. mm anyway since it's obviously a circuit supplying power to the lights?

Maybe "lighting circuit" means a control circuit for lighting, as opposed to one delivering power to the lights? Then there would be no contradiction between "lighting circuit" and "power circuit." Of course, we'd then be left with the nonsense of a lighting control circuit needing to be 1.0 sq. mm minimum while almost-identical (in terms of voltage and current) control circuits for other things come under other rules.

The whole thing is ridiculous.

 

[JohnW2]

Should I want to wire a circuit with a smaller csa than is apparently stated in the first part then I just have to use sheathed or non-sheathed flexible cable rather than sheathed or non-sheathed cable.

... except that one interpretation would say that you are not allowed to do that, becasue a "sheathed or non-sheathed flexible cable" is also a "sheathed or unsheathed cable". As we have all said, it is all seemingly nonsense - arguable ambiguous and possibly contradictory, and certainly ill-defined.

Kind Regards, John

 

[JohnW2]

By the way, did any of you who feel the Table is wrong make a comment to that effect during the public consultation?

I would have done at the same time that I commented (to no effect!) on the "Cmin issue", but I was under the impression that the consultation was in relation to just the proposed amendments, not a 'free for all' invitation for anyone to comment on any (unamended) parts that took their fancy. Did I misunderstand?

Kind Regards, John

 

[stillp]

I think the table is a selection from IEC 60364-5-52, but I'll try to check later.

Yes, it's based on Table 52.2 of IEC 60364-5-52. I can't copy the table here, but it includes the following Notes:

NOTE 4 In the UK, 1,0mm2 cable is allowed for use in lighting circuits.
NOTE 5 In the UK 1,0 mm2 copper cable is allowed for fixed installations utilizing cables and insulated conductors for power and lighting circuits.