Fire in fuse box

[Taylortwocities]

Yes, table 52.3 says minimum CSA for conductors and lists different types of circuits. That table says the minimum csa for lighting is 1.0mm but nowhere does it say that 1.0mm can only be used for lighting applications.

 

[Iggifer]

No but it says minimum for power is 1.5mm², and if a boiler is not lighting then it must be power. It's not signalling or control for sure.

Don't get me wrong, I think it's a ludicrous reg, I've said as much this week on the forum.

If they're both protected by a 6A MCB, what's the difference? The load on a boiler circuit is probably less than a lighting circuit

 

[crystal ball]

Just another badly thought out reg

 

[JohnW2]

No but it says minimum for power is 1.5mm², and if a boiler is not lighting then it must be power. It's not signalling or control for sure. Don't get me wrong, I think it's a ludicrous reg, I've said as much this week on the forum. If they're both protected by a 6A MCB, what's the difference? The load on a boiler circuit is probably less than a lighting circuit

Agreed. Whilst there are obviously some people for whom it is not an option, and given that we should not suggest deliberate non-compliance with regs, one could suggest that this seems to be a very stupid regulation which is screaming out to be ignored/broken!

Kind Regards, John

 

[Iggifer]

You're entitled to list it as a deviation from 7671 and I think anyone would be hard pushed to tell you it was unsafe to feed a boiler in 1mm

 

[JohnW2]

You're entitled to list it as a deviation from 7671 and I think anyone would be hard pushed to tell you it was unsafe to feed a boiler in 1mm

Indeed, but I suppose someone would probably try arguing that since it was clearly not a 'lighting circuit', someone might try using it to supply a much bigger load at some point in the future. However, I personally really don't think that one should have to make provision for possible idiotic and non-compliant things that might conceivably be done by someone in the future!

Kind Regards, John

 

[Taylortwocities]

I think anyone would be hard pushed to tell you it was unsafe to feed a boiler in 1mm

Yes. In that case I wonder why you raised it in your list of things to further worry the OP about!

1mm² used for the central heating

 

[EFLImpudence]

Table 52.3 is nonsense.

You will see that you could have used flexible cable "for a specific appliance - as specified in the product standard" or 0.75mm² flex "for any other application".
It could also be argued that "power circuits" means socket circuits.

So, 1mm² for a dedicated boiler supply is obviously fine.

 

[mfarrow]

I've used 0.75mm on our burglar alarm, in flex, it's on a C3 circuit breaker.

I could have used 1mm cable, but that would have been against regulations

All very daft!

 

[securespark]

Yeah, double dumb!

 

[Risteard]

As I have stated before I suspect it is a halfway house to banning 1mm^2 cable by stating that it can now only be used for lighting circuits. You must remember that nowhere else uses 1mm^2. The other argument is that it is easily fractured, although that risk still exists with an undefined lighting circuit.

To me a lighting circuit is one used predominantly for lighting but does not preclude fans/shaver sockets/smoke detectors being connected to that same "lighting circuit".

 

[EFLImpudence]

You must remember that nowhere else uses 1mm^2.

That's not really an argument against it, is it?
Do you know why nowhere else uses it - and is it literally "nowhere"?

If everyone is going to use 1.5mm² then we may as well use a 16A MCB.

The other argument is that it is easily fractured, although that risk still exists with an undefined lighting circuit.

You can always use flex.

To me a lighting circuit is one used predominantly for lighting but does not preclude fans/shaver sockets/smoke detectors being connected to that same "lighting circuit".

Exactly - so it is meaningless.
I presume it is because we label the CU "lights". If used for the other things then they should be added to the label otherwise how does anyone know?
However, it is just a circuit to which you can connect anything suitable.

 

[securespark]

As they all are.

I remember back in the early days of the 15th, fitting anything else to an immersion, cooker or shower circuit was discouraged, but these days you find security lights or loft sockets run off immersions, extra sockets run off cooker circuits and fans off shower circuits.

 

[JohnW2]

I remember back in the early days of the 15th, fitting anything else to an immersion, cooker or shower circuit was discouraged, but these days you find security lights or loft sockets run off immersions, extra sockets run off cooker circuits and fans off shower circuits.

Indeed - and, assuming it's done sensibly, why not? A circuit with a certain current supplying capacity is a circuit with a certain current-carrying capacity, regardless of the nature of the load.

Kind Regards, John

 

[securespark]

The guys I did my apprenticeship around did not use cooker circuits for anything else as they figured it could easily exceed 30A when busy ie Christmas etc...

Showers were not tapped off because they were 7kW wired in 4 milli...

I have even come across a few immersions in my time that were wired in 1 milli...