Hello circuitonians,

I bought a really cool 120v/300w light bulb from the 1910s and want to make a lamp out of it. Before plugging it in, I measured the resistance to make sure it hadn't turned into a dead short over the past 100 years (not likely, but whatever).

The cold filament resistance turned out to be 1 ohm. This seems really low. My bulb will be drawing 120 amps, at least for a few milliseconds until it heats up and the resistance increases! Should I be worried? I live in a big building without circuit breaker access, and I don't want to knock out the power for my neighbors/floor.

Basically, my question is: does standard 120V/20A wiring have provisions for surges in current?

 

That's not an uncommon resistance value to find on a higher wattage bulb.

Yes your 20 amp circuits will handle the 1 or 2 cycles that it takes for the bulb to heat up without a problem.

 

It will be a quite bright lamp, or maybe you plan to put a dimmer on it?

 

It will be a quite bright lamp, or maybe you plan to put a dimmer on it?

I was going to put a dimmer on it after I verify that the light bulb works and doesn't burn out immediately from air leaking in.

 

I was going to put a dimmer on it after I verified that the light bulb works and won't burn out immediately from air leaking in.

How will you know if there's air in the bulb before it burns out?

 

I won't - that's why I'm testing it!

Edit: Just tested. It burned out immediately. Probably should have used a variac. My eyes hurt. Thanks everyone.

 

I won't - that's why I'm testing it!

Edit: Just tested. It burned out immediately. Probably should have used a variac. My eyes hurt. Thanks everyone.

Why would you even mess with it? Did you really expect that light bulb to maintain a vacuum after 100 years? It was a collectors item and now I am sure you have reduced it's value because of the lose of the filament.

 

I won't - that's why I'm testing it!

Edit: Just tested. It burned out immediately. Probably should have used a variac. My eyes hurt. Thanks everyone.

Sorry for your loss.

 

Why would you even mess with it? Did you really expect that light bulb to maintain a vacuum after 100 years? It was a collectors item and now I am sure you have reduced it's value because of the lose of the filament.

Who collects light bulbs?

 

Who collects light bulbs?

The same type of person who collects old electronics.

 

Rats,

I was just testing one to warn you.

This 500 watt bulb is over 3 ohms.

It must have been really large watt or most likely a low voltage bulb.

Did it say on the bulb 120v and 300 watt? Doesn't make sense.

 

Who collects light bulbs?

Lots of people

This one for one

http://bulbs.2yr.net/galleries.php


People collect all kinds of strange things.

 

Rats,

I was just testing one to warn you.

This 500 watt bulb is over 3 ohms.

It must have been really large watt or most likely a low voltage bulb.

Did it say on the bulb 120v and 300 watt? Doesn't make sense.

Yeah, it came in a box with a sticker that said 120v and 300w. No big deal. It wasn't worth anything anyway.

I didn't really expect it to hold up after 100 years of sitting in storage....