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In reality it could be classed as supplying a fixed load if you only have a certain number of fittings with fixed wattage lamps.. in this scenario your cable doesn't actually require O/L protection and only short circuit protection.

In the domestic realm though this is not practiced as it would be subject to abuse and mis-understanding hence you are not taught this, but in design especially in the Industrial sector, utilising this exemption for O/L protect can save large amounts of money on material costs, the negative side been having O/L higher than you cable rating has the effect of reducing the permitted ELI - I've wired plenty a motor/machine supply where a cable CCC is lointo wer than the OCPD.

I personally wouldn't introduce this into the domestic realm as it just confuses the hell out of other Sparks that follow you.
 
The problem is that the minimum size cable for a lighting circuit is 1mm, and there are specific requirements about the type of flex or other protection to be used if flex is to be used as an installed cable.

could you just expand on what you mean by "other protection to be used if flex is to be used as an installed cable", surely if it's got a PVC outer like twin and earth has, and has insulated conductors inside, just like twin and earth, why would it require "other protection" when it's the same thing but a different shape?

im not looking to pick your comment apart, but more looking for clarity as I can't quite understand where you are going...
 
could you just expand on what you mean by "other protection to be used if flex is to be used as an installed cable", surely if it's got a PVC outer like twin and earth has, and has insulated conductors inside, just like twin and earth, why would it require "other protection" when it's the same thing but a different shape?

im not looking to pick your comment apart, but more looking for clarity as I can't quite understand where you are going...

I don't know exactly what, it's as ambiguous as the rest of 7671. go and look the regulation up and make your own decision, it's a couple of pages before the minimum sizes table. It has effectively replaced the regulation which used to set the maximum length of any installed flex to 2 metres.
 
So with reference to my post #8, Am I wrong in my interpretation of table 52.3 ?

I understand that 521.9 applies which is what Davesparks is referring to, and I would never personally consider flex for fixed wiring, or less than 1mm live conductors for any fixed circuit, but the table does seem to support the OP's ideas.
 
It's a confusing grey area I say, I suppose, the bottom line to this is if the cable is suitably protected or not, I will reevaluate my usage of 0.75mm cable and use 1mm from now on.

as said, this is only to feed an outside light, I am not a silly billy wiring an entire light circuit up with it.
 
It's a strange one actually, Reg 422.3.201 says suitably protected against mechanical damage, but it's strange how it doesn't say a word about suitable protection if it's twin and earth which is just a different shape...

why should flex need any more protection than any other cable irrespective of the CSA of the conductors.
 
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It's a strange one actually, Reg 422.3.201 says suitably protected against mechanical damage, but it's strange how it doesn't say a word about suitable protection if it's twin and earth which is just a different shape...

And different conductor construction, and insulation construction, and sheath construction.......
 
It's a strange one actually, Reg 422.3.201 says suitably protected against mechanical damage, but it's strange how it doesn't say a word about suitable protection if it's twin and earth which is just a different shape...

It's a fairly recent change in the regs which allowed flex to be installed at all, it was previously limited to 2 metres max length for appliance tails.
Every cable has to be suitably selected with regards to protection suitable for the environment it is in, regardless of what type it is.
 

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