Similarly, I have always wondered about the phrase "current using equipment" in BS7671 - it crops up in places, bathroom zones for example.
Surely every item of electrical equipment uses current, unless its switched off
Mains smoke and heat detectors
- Thread starter foxhole
- Start date
- Status
Similarly, I have always wondered about the phrase "current using equipment" in BS7671 - it crops up in places, bathroom zones for example.
Surely every item of electrical equipment uses current, unless its switched off
Sponsored Links
Surely, if we're being strict to the wording of the regs; a dedicated smoke circuit, would be, by definition, a Signalling (or control) circuit, and as such, 1.0mm² is perfectly acceptable anyway.
- Joined
- 11 Jan 2004
- Messages
- 42,890
- Reaction score
- 2,670
- Country
Could it be euro-harmonisation?
After all, that is the reason for most of the changes over the recent years.
As for "power", is there a definition of it in the beginning of the book?
For the purposes of the regs, it might be different to the definition we know and love.
52.3 is nonsense. It is not possible to comply with regulations which are nonsense. 52.3 has to be ignored.
Sponsored Links
Given that it is predominantly supplying luminaires I think it would be reasonable to class it as a lighting circuit and avail of the reduced csa permitted. It is a better option to supply smoke detectors from a lighting circuit anyway.
That is almost certainly the reason, but it was considered a half-way house to continue to permit 1mm^2 for lighting circuits.
As I said, it's silly to run a dedicated circuit for smokes anyway - a lighting circuit is a superior choice.
No it wouldn't. Only the interlink is a signal.
I would take that to mean equipment which uses current to develop power which is intended to do useful work, as opposed to equipment used merely to distribute or control current in which any power dissipated is incidental and wasted. So a lamp, a motor, a heating element would all be "current using" equipment, while cable, switches and fuses are not. I don't know if that would make sense against the particular way the term is used currently.Similarly, I have always wondered about the phrase "current using equipment" in BS7671 - it crops up in places, bathroom zones for example.
Surely every item of electrical equipment uses current, unless its switched off
If it's supplying power to the equipment, I wouldn't call that a signaling/control circuit, any more than I'd call the cable bring power to the primary of a doorbell transformer or a transformer for L.V. heating controls a signaling/control circuit.
I believe that many European countries have specified 1.5 sq. mm as the minimum permitted size for many years, but then I think few (if any?) European countries use 5 or 6A lighting circuits.
If that was the intent though, why not just specify 1.5 sq. mm minimum for everything? Maybe they just decided to do it in stages, and next edition 1.0 sq. mm will be gone completely.
So you're saying, so long as the link from the DB to smoke 1 is in 1.5mm² I can then run my interlink in 1.0mm to the next x no of smokes? That's patently ridiculous.
If it's the typical 3-conductor (plus earth) of 240V units though, only one of the three conductors is being used only for signaling purposes. The other two are still supplying power to the other detectors down the line.
But I agree it's ridiculous to say that 1.0 sq. mm is perfectly fine to feed several amps' worth of lighting but somehow is unacceptable to feed power to a few smoke detectors drawing a fraction of amp in total (unless they happen to be on a lighting circuit, assuming by the vague definitions in that table that adding the smoke detectors doesn't mean that the circuit ceases to be a "lighting circuit").
Assuming you have lights and smokes on the same circuit, at what point does it become a smoke or light circuit? If there's 3 lights and 3 smokes, which is it?
And I'm taking the literal definition of signalling, perhaps not the IEE definition of signalling, but the smokes signal to people that there's a fire/smoke
A good question. Wouldn't it be nice to know the answer?
They do, but there's a difference between "a circuit used to signal between signaling devices" and "a circuit used to supply power to signaling devices." Don't you think that "signaling circuit" means the former?but the smokes signal to people that there's a fire/smoke
If you plugged a portable mains-powered CO alarm or similar into a 13A socket, does that make the ring supplying that socket a signaling circuit?
Of course a circuit supplying only smoke detectors is not a lighting circuit although you could have some lights on your smoke detector circuit.
You could, of course, use flexible cable in which case it is allowed to use a smaller csa unless you consider 'sheathed or unsheathed flexible cable' is also a 'sheathed or unsheathed cable' in which case you can't.
The table is patently ridiculous - ignore it.
It is perfectly possible to comply. What is "nonsense" about it?
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
- Status
Sponsored Links
