Say a lightbulb pops in your house; you go to the store for a replacement, but you arent sure if the switch is ON or OF. If the switch is on, is there a risk of fire? This is a longstanding debate in my house… Personally I think its harmless… am I wrong?
No, you’re not wrong.
No, it’s not dangerous, but the improper thread placement could well give you The Sick.
To turn GQ-ish for a moment, there is nothing flammable in the bulb that could cause a problem.
What’s really hazardous (not) is if you turn the light switch on and there is no bulb in the fixture - electricity could leak out all over the house - very dangerous (there was a good Thurber story about a relative of his who believed this).
Its not especially dangerous but leaving a powered light socket open is not exactly the greatest idea. There still is a live circuit there and if, say, your finger were to complete it you would be in for quite the, heh, shock.
The circuit is broken, and unless the fixture is of poor quality, there should be no more danger of having a hot wire in it than there is of having a hot wire at the switch, which is always the case. It’s probably more dangerous with a good bulb, since you have heat issues that you don’t have with the bad bulb.
Now, a person might think the fixture was powered off, so there’s an electrocution risk if they decide to monkey around with it. Other than that I’d say it was perfectly safe.
Must you? Here?
Not really, hot wires in switches are nicely tucked behind plastic while it would be sort of exposed in a light socket.
I’m pretty sure this question has an actual answer that does not need to be debated.
Off to GQ.
I think Cheesesteak nailed it. The OP may be slightly unclear, but it seems to be saying that the burned-out bulb is still in the socket. This produces no additional risk of fire (and may even slightly reduce the risk).
“good Thurber story” is a totally and completely unecessary redundancy. 
Go to the blackboard and write 100 times. “There are no bad Thurber stories.”
When I light bulb burns out, I always turn the light off. Why? So when I go to screw in the replacement, it doesn’t suddenly light up in my hands. That freaks me out. I know it hasn’t had time to really heat up yet, but still, I don’t wanna be touchin’ no lit-up lightbulb.
Yeah you are probably right. I interpeted go to get a replacement to mean that he takes the bulb to compare and make sure he gets the right kind. If you leave the Bulb in the socket there is no danger as far as I know.
Think of it this way. When you turn off a light switch, you are causing a break in the flow of electricity by disconnecting two wires from each other. When the filament burns out, it causes a break in the flow of electricity because there is no longer a complete circuit. The burned out filament is acting exactly like a switch in the “off” position.
For non filament bulbs, does the same answer to the OP apply?
Installing a flourescent bulb in a socket that has power to it merely means that the bulb will light up when the circuit is completed. Not dangerous unless you stick a finger into the socket.
On the other hand, if you have a dimmer switch on the bulb, you may want to make sure the power is off before you change the bulb. I fried a dimmer switch while putting in a new bulb. Probably because the bulb makes poor contact until it is screwed in all the way.
Sparks and smoke came out of the switch, and then all the lights on that curcuit went out. :eek: