I have been playing with an AFDD as I am rather skeptical about their use. The USA experience is not good, the primary stated purpose being to protect the appliance cables, extensions etc not the fixed wiring. Since introduction about 12 years ago there has been no statistical evidence that they prevent fires, but I do not have the direct data so cannot be sure. In the USA they are much cheaper than here, but still more than a standard MCB (try looking at home depot prices, the model for B&Q) online. Realistically arcs occur in any electric motor with brushes, and on switch on and off of any load, and these must not trip the AFDD, So far I have had remarkably little luck tripping one at all, but have not really managed a sustained arc of suitable current despite trying quite hard.  Further information when I have it!

I have been playing with an AFDD as I am rather skeptical about their use. The USA experience is not good, the primary stated purpose being to protect the appliance cables, extensions etc not the fixed wiring. Since introduction about 12 years ago there has been no statistical evidence that they prevent fires, but I do not have the direct data so cannot be sure. In the USA they are much cheaper than here, but still more than a standard MCB (try looking at home depot prices, the model for B&Q) online. Realistically arcs occur in any electric motor with brushes, and on switch on and off of any load, and these must not trip the AFDD, So far I have had remarkably little luck tripping one at all, but have not really managed a sustained arc of suitable current despite trying quite hard.  Further information when I have it!