420 Watt Hedge Trimmer.

That is an interesting outcome because the exact amount of energy to operate each device must have all been achieved together. I would expect both B16s to operate because the fault current was probably in the "instant" range, and this must be very similar to the current required to blow a 5A fuse too, in much the same time. Dead shorts are always likely to do something like this, due to the high current and the very short period needed to operate CPDs. It shows exactly why submains (garage feed) with low value CPDs do not discriminate and therefore are a nuisance! This would puzzle the average consumer for some time as to what the fault was! Another point is that the 5A fuse may have been old, and they do "age" somewhat due to transient overloads etc, so if he does it again the new fuse may hold up.

That is an interesting outcome because the exact amount of energy to operate each device must have all been achieved together. I would expect both B16s to operate because the fault current was probably in the "instant" range, and this must be very similar to the current required to blow a 5A fuse too, in much the same time. Dead shorts are always likely to do something like this, due to the high current and the very short period needed to operate CPDs. It shows exactly why submains (garage feed) with low value CPDs do not discriminate and therefore are a nuisance! This would puzzle the average consumer for some time as to what the fault was! Another point is that the 5A fuse may have been old, and they do "age" somewhat due to transient overloads etc, so if he does it again the new fuse may hold up.