New/replacement socket-outlet circuits require arc fault detection devices (AFDDs) and surge protection (SPD)

As I read the regs unless it's a Higher Risk Residential Building (e.g. >18m tall), House in Multiple Occupation, purpose built Student Accommodation or a Care Home, there's no requirement for AFDDs. There may be a recommendation, but that's not quite the same as a requirement, and I've yet to meet anyone who actually installs AFDDs commercially when they don't need to.

I agree an SPD would likely be required, but that can be retrofitted without a complete CU change (space and aesthetics permitting) - either in a separate enclosure fed from the existing CU, or even in the supply tails (e.g. https://www.tlc-direct.co.uk/Products/WYREC2SPD.html)

   - Andy.

AJJewsbury said:

As I read the regs unless it's a Higher Risk Residential Building (e.g. >18m tall), House in Multiple Occupation, purpose built Student Accommodation or a Care Home, there's no requirement for AFDDs.

There's a recommendation, though.

As some see it, 'do it unless there's a good reason not to' (because you might be asked 'why' if something goes wrong?

Kitchen ... may be full of  heavy current-using equipment, and almost certainly a fridge-freezer (in which the fire was, on the balance of probabilities, started at Grenfell) ... perhaps a good reason to use AFDD (in the opinion of the person designing the modifications to the installation)?

AJJewsbury said:

As I read the regs unless it's a Higher Risk Residential Building (e.g. >18m tall), House in Multiple Occupation, purpose built Student Accommodation or a Care Home, there's no requirement for AFDDs.

There's a recommendation, though.

As some see it, 'do it unless there's a good reason not to' (because you might be asked 'why' if something goes wrong?

Kitchen ... may be full of  heavy current-using equipment, and almost certainly a fridge-freezer (in which the fire was, on the balance of probabilities, started at Grenfell) ... perhaps a good reason to use AFDD (in the opinion of the person designing the modifications to the installation)?

and almost certainly a fridge-freezer

And most AFDDs don't work for currents below 2.5A ... which most domestic fridge freezers won't draw - so little chance of an AFDD spotting a series arc there. It might spot an parallel arc - but then an RCBO is likely to too. There again the fault might have been simple resistive heating, which nothing would have spotted.

Cooking appliances (or showers) might be a better bet - but there's not even recommendation for AFDDs for those (unless plugged into a socket...)

   - Andy.

AJJewsbury said:

nd most AFDDs don't work for currents below 2.5A ... which most domestic fridge freezers won't draw -

A parallel arc might temporarily or intermittently, though ????

AJJewsbury said:

Cooking appliances (or showers) might be a better bet - but there's not even recommendation for AFDDs for those (unless plugged into a socket...)

Perhaps have a look at reports on statistics, but if memory serves, a lot of cooking appliance fires are not (initially) related to electrical faults in the appliance itself. I believe (but we would need to check up) that top of the list of appliances after cookers (ovens/hobs) and microwaves that might be associated with fires are 'white goods' (in no particular order washing machines, tumble dryers and fridge-freezers).

A parallel arc might temporarily or intermittently, though ????

The AFDD demos I've seem seem to suggest they only respond after several seconds of arcing (no doubt to reduce unwanted tripping) - so it feels likely an RCBO will have got there first for parallel arcs.

Perhaps have a look at reports on statistics,

My thought behind showers/cookers was the common reports of terminals burning out in shower pull switches and (perhaps less often) DP switches for cookers.

  - Andy.