Bulbs normally burn out open, breaking the circuit. And in the unusual case that they don't, I would imagine the thin wires leading to the filament will melt, also breaking the circuit.

And if all else fails you your circuit breaker should flip.

If bulbs normally failed short, then you'd have circuit breaker's flipping a lot more often.

They can be a little spectacular when they fail short. My last incandescent (a bathroom light) did it a few weeks ago, exploding the glass of the bulb and popping the breaker for my downstairs circuit.

Why? A burned-out bulb fails closed not open.

If it failed open then a bulb burning out would trip the circuit breaker.

> Why? A burned-out bulb fails closed not open.

In electrical circuit terminology, "open" means "not connected" while "closed" means "connected/shorted".

That's different from direct translation of Chinese (and I think several European languages) where "open the light" means to turn it on (by closing the circuit, naturally).

I think it's most common English engineering usage (by far) to say that a burned out lamp fails open [circuit].

Whoops, sorry, I had them reversed!

Interesting/random side note: modern mini Christmas light bulbs do burn out (mostly) closed: https://www.youtube.com/watch?v=0MOpfT0f7bQ&t=179s

To close a circuit is to connect it, correct? So when the filament burns out, the circuit breaks, which is an open circuit, correct?

If you want exciting look up floating neutral.

the neutral grounds both sides of the split phase and mainly serves to carry current when the load on each phase is unbalanced. when the neutral is cut off from ground all current has to be carried by the phase. if the loads are balanced, everything appears fine. when it is not you end up with a spooky electrical system. as now you have a series connection with a built in voltage divider. on one side the voltage will be too high on the other too low.