Mains smoke and heat detectors

[stillp]

More chance of mechanical damage for the circuits within reach. As I said, it's a guess.

For fixed cables protected by the fabric of the building?

And fixed cables that are surface-mounted, and the devices connected to that fixed wiring, and even fixed wiring that is enclosed in conduit or trunking, or on cable tray. Remember these standards deal with installations, not just domestic.

 

[EFLImpudence]

stillp - I'm beginning to think you wrote Table 52.3 and got it wrong.

 

[EFLImpudence]

And fixed cables that are surface-mounted, and the devices connected to that fixed wiring, and even fixed wiring that is enclosed in conduit or trunking, or on cable tray. Remember these standards deal with installations, not just domestic.

What is the difference in lighting and power with cables installed in such ways?

 

[stillp]

FWIW I think that it means "A circuit that the designer considered to be a lighting circuit" and "A circuit that the designer considered to be a power circuit".

But what IS a "power circuit"? How can the designer consider whether his circuit is, or is not, something undefined?

By considering which of the available categories is more appropriate to the circuit he's designing.

 

[stillp]

Because your fan, with a plug on, is outside the scope of the standard and is irrelevant to the purpose of the circuit as designed.

Well in that case so is everything, and I could use 1mm² for any circuit I choose and say "yes, it may very well be supplying smoke detectors, a couple of fans, a shaver socket and a TV, but they are all out of scope, and therefore irrelevant, and therefore it is a lighting circuit."

No, you're missing the point. The standards we are discussing apply to the installation. They cannot deal with every possibility that might arise in the use of that installation, so if the designer plans and installs a lighting circuit he has no control over what might be plugged into that circuit, just as the designer of a circuit for socket-outlets cannot predict the idiot who wants to plug in a 6 kW hot tub.

 

[stillp]

And fixed cables that are surface-mounted, and the devices connected to that fixed wiring, and even fixed wiring that is enclosed in conduit or trunking, or on cable tray. Remember these standards deal with installations, not just domestic.

What is the difference in lighting and power with cables installed in such ways?

None.

 

[stillp]

stillp - I'm beginning to think you wrote Table 52.3 and got it wrong.

No, I've written parts of a number of standards, but I don't deal with installation standards. I do have to use them on occasion, and let me tell you there are far worse provisions in some of the standards from that TC.
I'm not defending the table, I just want to refute the suggestion that anybody who doesn't understand the reasons behind it can simply ignore it, and still claim compliance with the standard. As I've written earlier, compliance with a standard involves compliance will all its normative provisions. [Bearing in mind that BS7671 allows deviations, which I still have to discuss with my QC in the new year].

 

[ban-all-sheds]

FWIW I think that it means "A circuit that the designer considered to be a lighting circuit" and "A circuit that the designer considered to be a power circuit".

But what IS a "power circuit"? How can the designer consider whether his circuit is, or is not, something undefined?

By considering which of the available categories is more appropriate to the circuit he's designing.

Yes, but what is the "power circuit" category?

 

[stillp]

A circuit that isn't a lighting circuit? (Other than the other categories that we are not discussing).

 

[ban-all-sheds]

I just want to refute the suggestion that anybody who doesn't understand the reasons behind it can simply ignore it, and still claim compliance with the standard.

But that's not what's going on. The Table could be reworded, and terms properly defined, and it would be quite possible to comply with it. One might have no idea as to why the requirements were there, and I'm sure there would be people who would still refuse to do it because they disagreed with the requirements, but ignorance of the underlying reasons would not be a block to compliance.

What is going on here is that it is quite simply impossible to comply with nonsense.

 

[ban-all-sheds]

A circuit that isn't a lighting circuit? (Other than the other categories that we are not discussing).

What's a "lighting circuit"?

One which only supplies lights?

One which supplies mostly lights, as measured by count?

One which supplies mostly lights, as measured by total load?

One which supplies at least 1 light and any amount of other things?


Do you not see the problem?

 

[stillp]

What is going on here is that it is quite simply impossible to comply with nonsense.

Of course compliance is possible. If you find the decision too difficult, just use 1.5 mm².

 

[stillp]

A circuit that isn't a lighting circuit? (Other than the other categories that we are not discussing).

What's a "lighting circuit"?

One which only supplies lights?

One which supplies mostly lights, as measured by count?

One which supplies mostly lights, as measured by total load?

One which supplies at least 1 light and any amount of other things?


Do you not see the problem?

No, I don't.

 

[stillp]

The Table could be reworded, and terms properly defined, and it would be quite possible to comply with it.

Have you made a proposal to IEC TC64? Or to BSI JPEL/64? Or to the IET?

Thought not.

 

[ban-all-sheds]

Of course compliance is possible.

No it is not, because there are no definitions which can be used to determine which category a circuit is in.

If you find the decision too difficult, just use 1.5 mm².

But what if I have good reasons for wanting to use 1.0mm² and I want to know if it is allowed, given the type of circuit I have?

Do you not see the problem?

No, I don't.

Then IMO you should not have any involvement in writing or QAing standards.