MCB, RCD & AFDD all in one

[Nigel]

In conclusion if you are installing sockets in a building that requires AFDDs don’t install RFCs.

 

[Marvo]

Whilst AFD's don't detect series arc faults on a ring final cct that mode of fault is not as dangerous on a ring because of the parallel path available for the load current so it's kinda swings and roundabouts....

 

[paullyons]

This may shed a bit more light on what the future holds

 

[johnduffell]

Things can be in the regs even without a tester - after all there's never been a tester for the magnetic or thermal parts of an MCB/RCBO, only for the residual current part. Dame goes for fuses for that matter. so we have no idea if they still work when doing inspection and testing.

 

[Bobster]

Things can be in the regs even without a tester - after all there's never been a tester for the magnetic or thermal parts of an MCB/RCBO, only for the residual current part. Dame goes for fuses for that matter. so we have no idea if they still work when doing inspection and testing.

But if a fuse blows or an MCB trips you have test equipment to diagnose the fault quickly and reliably every time.

No such thing with these devices, one might keep tripping due to a natural arc in a circuit (something switching). How do you fault find that.... just start replacing parts at an unnecessary cost.

 

[Spoon]

'premises with sleeping accommodation' is a bit ambiguous, though. I'm assuming they mean hotels?

It is very ambiguous. The Oxford Dictionary says 'Accommodation' is "A room, group of rooms, or building in which someone may live or stay. ‘they were living in temporary accommodation’ "

Doesn't that put every house down as having "sleeping accommodation" ?

 

[johnduffell]

But if a fuse blows or an MCB trips you have test equipment to diagnose the fault quickly and reliably every time.

Yes, you can just look at the switch or at the melted fuse. But the same applies to the afdd. I thought people meant testing the device itself for correct operation, which you can only do with rcds.

With rcds you can test the rcd itself, and you can ir test the circuit.

With fuses and mcbs you can only test the circuit.
With afdds not sure! Maybe neither?

 

[Wilko]

It is very ambiguous. The Oxford Dictionary says 'Accommodation' is "A room, group of rooms, or building in which someone may live or stay. ‘they were living in temporary accommodation’ "

Doesn't that put every house down as having "sleeping accommodation" ?

Yep.
Fortunately 421.1.7 has two softeners for now. It says "If used..." and then gives "Examples of where such devices can be used...". This will change to "shall be used" at some point I guess.

 

[Bobster]

With fuses and mcbs you can only test the circuit.
With afdds not sure! Maybe neither?

Neither unless you're in a lab.

You maybe able to pick up a fault on the circuit with an IR but doubtful, as a L>N short should trip the MCB.

 

[Spoon]

Yep.
Fortunately 421.1.7 has two softeners for now. It says "If used..." and then gives "Examples of where such devices can be used...". This will change to "shall be used" at some point I guess.

But, pinching this from the earlier post, it also has:
421.1.7 arc fault detection devices conforming to BS EN 62606 are recommended as a means of providing additional protection against fire caused by arc faults in AC final circuits.

If there is a fire and it goes to court and the court says "BS6761 recommend that you use Arc Fault Detection Devices. Why didn't you fit them?" Where would you stand from a legal point of view?