Christmas lights, I don't get it...

steveinaz

How come, if you take a bad bulb out, you'll lose power to some of the lights---BUT---if you put the bad bulb back in, they'll light back up? Wouldn't a broken filament mean an "open" circuit, just the same as removing the bulb completely?

I'm baffled.

Willow

Maybe so you can't stick an object in and get shocked

treitz3

Page 2, section 4, paragraph 15 should explain it.

bobman1235

Sometimes when the filament breaks, the two things that were HOLDING the filament are either touching or close enough to carry a current. It doesn't take much.


EDIT just a guess, btw.

madmax

I'll bet it either has more than 2 conductors to the bulb OR it fails in a shorted condition.

Rev. Hayes

Aren't a lot of christmas lights run in a parallel circuit?

shadowofnight

The older light strings used to mostly use a series wiring setup ( One die/all die ), newer ones tend to use a few different types.

http://www.wisegeek.com/why-does-an-entire-string-of-christmas-lights-fail-when-a-single-bulb-burns-out.htm

mhardy6647

I think that the longer strings of the "subminiature" incandescent lamps (which, if memory serves, are 3V filaments) are wired series parallel. For example (and just for illustration!), a hypothetical 120 lamp string might have three series strings of lamps (40 each), and those three strings might be paralleled to plug into the mains outlet. Each series string would drop 120 volts. A lamp failing in one series string would break continuity in that string; those 40 lamps would be kaput... but the other two would still light.

That said...

Many modern (so to speak) strings of the subminiature bulbs had shunts in the sockets; if one lamp burns out, the shunt conducts the juice instead of the filament and the series string stays lit.

steveinaz

That's what I was thinking, sort of a "quasi-parallel" setup or something. Wierd.

Erik Tracy

steveinaz wrote: »

How come, if you take a bad bulb out, you'll lose power to some of the lights---BUT---if you put the bad bulb back in, they'll light back up? Wouldn't a broken filament mean an "open" circuit, just the same as removing the bulb completely?

I'm baffled.

You live in the SW - why not go 'old school' and make faralitos (aka luminarios)? :biggrin:

Tony M

Think of the letter H,

With the top having the filament that lights. The middle piece always carries the current.

George Grand

tony millard wrote: »

Think of the letter H,

With the top having the filament that lights. The middle piece always carries the current.

This is the type technical description the world yearns for. Good man.

I thought for sure the thread would be about Christmas lighting. The guy next door to me makes Clark Griswold look bad.

maximillian

mhardy6647 wrote: »

Many modern (so to speak) strings of the subminiature bulbs had shunts in the sockets; if one lamp burns out, the shunt conducts the juice instead of the filament and the series string stays lit.

I think the shunts are in the lamps. If you pull a burnt lamp (where the string is still lit) then the string goes out.

tonyb

Christmas lights are like picking up a ****, just no good way to handle them.

inspiredsports

I think they used to call it a "shunt" type bulb used in old series wired light strings. A solid shunt wire is present in addition to the filament that can/will burn out. The solid shunt stays put keeping the string lit.

RuSsMaN

George Grand wrote: »

This is the type technical description the world yearns for. Good man.

I thought for sure the thread would be about Christmas lighting. The guy next door to me makes Clark Griswold look bad.

Bingo.

Even I understand now.

steveinaz

tony millard wrote: »

Think of the letter H,

With the top having the filament that lights. The middle piece always carries the current.

GOT IT! That makes perfect sense.