I don't know the figures off the top of my head, but is that really a significant issue?
Kind Regards, John
As far as I am aware about the only house hold item which is likely to be damaged due to volt drop is the fridge/freezer. The overload which switches the unit off should is stall due to trying to start before pressure has dropped fail if used too often, and with a volt drop this can happen.
So you will see it states with most do not use an extension lead. The problem is as well as the resistance of the lead, there is also a resistance in the fuse, 13A I think 0.04Ω which is not a lot, but I have seen a 1 to 3 adaptor in the plug feeding three 4 way extension leads in the main for audio/vision so very little load but then one off that to chest freezer so 3 fuses plus length of lead so easy to get to 1Ω = 13 volt at 13 amp. Add this to the volt drop at the outlet and now it has reached the point where a freezer may fail.
Where I had the problem was Algeria, we had often a 220 volt supply and were using British equipment rated at 240 volt so 20 volt before we even started, we has some Dutch and some British electricians and the Dutch would set output to 220 and British to 240 and it was noted not as many AC units failed on the camps with British electricians in charge.
Fluorescent lights also very voltage sensitive but don't tend to be plugged in, and radio transceivers, problem with latter often only on transmit so user may be unaware of the problem. I have had problems with a shrink rap machine, but that was not domestic. In the main the switch mode power supply has removed the problem with volt drop, my fridge/freezer is three phase powered by an inverter (built in) so today modern fridge/freezers don't have the same problem, however instructions still say don't use an extension lead.
In theory every 13A socket on a ring final should have an loop impedance of 1.44Ω or better, radials could be 2.87Ω and a fused spur 2.42Ω (13 amp) and 16.4Ω (3 amp) however how often does a person adding a socket actually check the loop impedance, should clearly do it every time with fixed wiring but with portable extension leads rare. When PAT tested there is a pass limit, can't remember off hand, but nothing stopping a device in a device, and nearly every plug in item has a fuse, time clock, energy monitor, all add to the resistance.