Has anyone figured out what the new version of 433.3.1 is all about?

It's confusing me... it's under the heading of 'omission of devices for protection from overload' but it reads as if it's about the position of such devices, not their omission (i.e. it looks like a rewrite of 433.2.2 but it's been put under 433.3.1). Some of the new re-wording seems a bit vague to me too - e.g. what's "Where automatic disconnection of supply is inappropriate" meant to mean in this context?

and why "(c) A device for protection against overload need not be provided for circuits for telecommunications, control, signalling and the like." - what's the idea behind that? Some will be safe enough because the source won't be able to supply excess current (or will just shutdown), but some control circuits are mains derived or from substantial sources, and I would have thought could pose a fire risk if overloaded (e.g. if someone plugs in too many phones or PoE devices or replaces a lamp with the wrong rating) - a blanket "don't bother" seems a bit flippant...

   - Andy.

(edited to remove erroneous talk of faults)

AJJewsbury said:

and why "(c) A device for protection against overload need not be provided for circuits for telecommunications, control, signalling and the like." - what's the idea behind that? Some will be safe enough because the source won't be able to supply excess current (or will just shutdown), but some control circuits are mains derived or from substantial sources, and I would have thought could pose a fire risk if overloaded (e.g. if someone plugs in too many phones or PoE devices or replaces a lamp with the wrong rating) - a blanket "don't bother" seems a bit flippant...

I would hope that would be covered by the relevant equipment standards.  For example, a PoE adaptorshouldn't catch fire if you connect too many pieces of equipment to it.

For example, a PoE adaptorshouldn't catch fire if you connect too many pieces of equipment to it.

Indeed - which used to be covered by the "characteristics of the load or supply" clause - which seems simple and safe - and useful for many situations - but they seem to have removed that option and replaced it will an assumption that " telecommunications, control, signalling and the like" will never need overload protection and everything else will - which feels a bit blinkered.

   - Andy.

Well you could read that that the boiler heating control wiring, which in a traditional arrangement are 'mains level logic' now need not have ADS except an RCD direct off the 100a main supply fuse, and I suspect that meaning is NOT intended.

Mike.

Well you could read that that the boiler heating control wiring, which in a traditional arrangement are 'mains level logic' now need not have ADS except an RCD direct off the 100a main supply fuse, and I suspect that meaning is NOT intended.

Mike.