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Author Topic: left-hand bulbs?  (Read 15516 times)

Offline Hemingray

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left-hand bulbs?
« on: March 29, 2006, 03:15:21 pm »
Have two GE 100W/120V edison base bulbs (picutres soon) that have a left-hand threaded base. any idea what these are supposed to be used for? they will not fit in a regular socket at all, so I can't test to see if they work or not. they came in a box of bulbs I bought at a thrift store for $3.00

Offline Tim

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Re: left-hand bulbs?
« Reply #1 on: March 29, 2006, 03:44:29 pm »
Theft deterrent!? As you discovered, this bulb is unuseable in any common household lamp socket.? Such bulbs were made with left-handed threads to deter people from stealing light bulbs and using them for their own purpose.? I?ve heard ?left-handed? bulbs were once prevelant in motels and other public places where bulb theft was common.? I don't know when they went out of style...

Offline Mónico González

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Re: left-hand bulbs?
« Reply #2 on: April 03, 2006, 08:17:01 am »
By the same reason in the pre-meter distribution era, some electric companies fitted the user's intallations with lampholders quite different from those sockets in use in each country. I.e., here in Spain, where the Edison E27 and E14 have been the standard cap fitting for regular household lamps almost from first electrifications, some early companies did use the Swan B22-d to avoid their users could change the lamps they have been installed for more powerful anothers.
When to change a lamp were needed, the Company had to sell a new one to the user.

An example of this particular kind of "company lamps" are (in Spanish) here:

M. Gonz?lez.
« Last Edit: April 03, 2006, 08:36:02 am by M?nico Gonz?lez »

Offline jonathan cassiday

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Re: left-hand bulbs?
« Reply #3 on: April 06, 2006, 10:14:55 pm »
I have also heard of left hand threaded light bulbs being used in the old style subway cars and there is some info on them on a web site about the NYC subway systems, I once found some information at this web site but it may have changed since i last looked,

the spcific article i found this in is posted on this page
yes this is Jonathan Cassiday how may i help you

Offline James

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Re: left-hand bulbs?
« Reply #4 on: May 11, 2006, 06:10:20 pm »
Left hand threaded lamps are still in mass production at GE!  I believe they first came out in the 1970s, at the request of the public transport department in San Francisco, to deter bulb thefts from tram cars.  They are still made today for the same application.  It is termed the EX26 base instead of the usual E26 designation.

Similarly British trains continue to employ bayonet capped lamps, but having a third side pin which prevents insertion in a standard lamp holder.


Offline jonathan cassiday

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Re: left-hand bulbs?
« Reply #5 on: May 24, 2006, 10:13:57 pm »
found a great list of explanations of let handed threaded light bulbs at this site, along with the specific snipit

The Challenge - Left-hand Threaded Light Bulbs...

The situation presented in the last edition of the newsletter was: What were light bulbs with left-hand threads made for, and why were they made this way?

Answer: Light bulbs with left-handed threads were originally made for use in public places, such as on trains and subways. The intent was to curtail theft ? as they were useless in the home, no one would steal more than a few before realizing the bulbs wouldn't work with a regular base. These bulbs can still be purchased; they fall under the classification of specialty bulbs.

Here's a sample of your responses...

"Light bulbs with left-hand threads were used on New York City subway cars. There were made this way because they had a problem of the light bulbs getting stolen by the passengers. The passengers were stealing them to use them at home. Changing to left-hand threads made the light bulbs worthless to steal because nobody had left-hand threaded bulb sockets at home."

"Light bulbs with left-hand threads were made for use in public places to deter thieves, because they would not fit in residential lighting fixtures."

"Left-hand bulbs are often used in temporary lighting strings at construction sites. Left-hand threaded bulbs do not fit in normal Edison-based sockets found in most incandescent fixtures, so therefore no one would want to steal them."

"The reason left-hand thread bulbs are made is quite simple: people won't steal what they can't use."

"Left-hand threaded bulbs are produced for use in public places. This is to deter theft, since one cannot use them in standard household fixtures. Left-hand bulbs are still available... make the perfect gift!"

"The reason for light bulbs with L-hand threads is a safety concern. On rotating equipment that is spinning in a clockwise direction, L-hand threads are necessary so that centrifugal force is directed in the tightening direction rather than loosening, thus preventing the bulb from becoming a flying projectile and a bonanza for personal injury lawyers."

"You can still buy left-handed light bulbs for the purpose of theft prevention (New York’s subway system is one such client), but I seem to remember something about Tesla’s fight with Edison over DC vs. AC current having something to do with the evolution of right vs. left-hand bulb threads. (This is only a vague, semi-recollected memory of something from long ago, and has no scientific validity.)"

"Construction sites so people would not steal them. I think this goes along with the little boy on Art Linkletter who, when asked what his father did for a living, said, "My father makes light bulbs and toilet paper." When asked how he knew this, the boy responded, 'That's all he brings home from work.'"
yes this is Jonathan Cassiday how may i help you

Offline ewildes

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Re: left-hand bulbs?
« Reply #6 on: September 18, 2006, 12:32:58 am »
How come nobody said that left handed bulbs were for south of the equator?