"I have been but little in," said Ninian hastily...

A discussion on my UK editors list has degenerated (as the good threads usually do :-) into something totally unrelated to work, namely electrical wiring.

Specifically, and this has me completely confused, the assertion by several members that they've been told by electricians that to comply with the new ("new" = four years old) electrical regulation called Part P, all the fixed lights in their house have to be on a single circuit (and all the plugs have to be on a single separate circuit). Looking up Part P myself, I find that it's suggested model plan does nothing of the sort; it puts all fixed lights on each *floor* on one circuit and all plugs on each floor on one circuit. Now, that still seems like overkill to me; why not do what we do here in the US, and have them circuited room by room? That way if the lights go out in the kitchen, I don't trip over everything in the dark on my way to the fuse box.

Which brings up the part that REALLY confuses me. All these folks are claiming that every time one of the lightbulbs blows, the CIRCUIT BREAKER TRIPS! WHAAAAA? Why on earth would the circuit breaker trip when a lightbulb goes *out*. We're not talking explosive decompression or implosion here, just an ordinary incandescent lightbulb has the tungsten coil inside fail and it stops generating light. Why on EARTH would that make the breaker trip, ESPECIALLY if that means every light in the floor (or house, since I don't doubt that these folks are telling the truth, just that what their builders are doing is actually the requirement of the code). This makes NO sense to me.

Can someone wise in the way of volt and amp explain?