If ONE Goes Out They ALL Go Out - ECN Electrical Forums

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Up until 1946, when Christmas lighting production resumed after World War II, by far the most popular style of electric Christmas lights in use were the series wired type, which meant that if one bulb failed, the entire string went out. Many a frustrated decorator was often relegated to dreaded "search and replace" duty, spending the better part of a December evening searching for that elusive burnt out lamp. Covered on this page are some industry attempts at solving this most frustrating problem...

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Apco brand series light tester, designed to make finding a burnt out lamp a bit easier. The user was to grip the wires coming from the light socket firmly with the device, which would puncture the covering of the wires and short out the socket. If the string lit, the the defective lamp was found, if not, then the user would proceed to the next socket and so on. This device added greatly to the fraying problem frequently found with series wired lighting sets.

1923 patent application for Detect-O-Lite system

Many Thanks to Bill Nelson! www.oldchristmaslights.com

[This message has been edited by Webmaster (edited 08-08-2003).]

Thanks for the link -- I could browse through this sort of stuff all night and have added it to my favorites to go back and look at in depth! [Linked Image]

I have many years' worth of memories of playing "hunt the blown bulb" on light strings. Fancy electronic chaser lights and such like have become popular in recent years in Britain, but the old series chain is probably still the most common. Our chains are usually twenty 12V lamps for 240V operation.

The bulbs are supposed to short out when they blow to keep the rest of the chain alight, but it doesn't always work out that way.

Neat link!

A non-contact voltage probe often works to find the blown bulb. Hold it against the glass part of the bulbs, work your way along the string to find the last bulb that make the probe beep. This is the blown bulb.

Usually, the miniature X-mas tree bulbs in series have a little shunt on the base of the two filament supports.

When the filament in one bulb burns out the shunt takes over. The voltage to the rest of the bulbs rises slightly.

Eventually as more bulbs burn out and more shunts take over, the voltage rises to the point where the rest of the string just goes.

That's why the packages say to "replace burnt bulbs promptly to avoid overheating of the remainder."

I love this type of thing too. That tool looks very familiar.

We used to have a set of lights where the individual Bulbs were in the shape of Santa, etc. I remember some figures being elongated and different from what we are used to seeing now.

I wonder if they're still around somewhere ... hmmm

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Bill

Read this article on Howstuffworks.com: http://home.howstuffworks.com/christmas-lights.htm

It has a good bit of info on old and new Christmas lights, including the fact that new lights aren't wired in parellel

I noticed the link to the christmas light site doesn't work; according to some forums I looked at the owner recently passed away. Just FYI...

Are you talking about oldchristmaslights.com?

His latest update was in December 11. Unless something happened between then and now.... [Linked Image]

The site is back up.

It appears someone has taken over from him. It was formerly run by someone named Bill.

More info here for those interested:
http://bulbcollector.com/forum/index.php?topic=64.0