I was browsing an online light bulb catalog and came across left hand thread light bulbs. It must be for some type specialty applications. Out of curiosity what fixtures or applications use left hand thread? Thanks.

I was told that there is a hotel in the USA which uses these special bulbs as they seems to be more theft- proof...? 

I was browsing an online light bulb catalog and came across left hand thread light bulbs. It must be for some type specialty applications. Out of curiosity what fixtures or applications use left hand thread? Thanks.

Some time ago E29 sockets were used on bulbs in public areas as a measure to prevent lamp thefts, I would guess it would be the same reason with the left hand thread.
Experience from the maintenance of the corridor lights in the apartment building, where my parents live: When the glass is loosened from the socket after screwing into the fixture (so it is impossible to unscrew the lamp without completely destroying the lamp), "due to unknown reason" such lamps work there many times longer than the ones not "treated" in that way...

Wonder what they will do wih CFLs now... Looks like the time of custom-ordered lightbulbs in small quantities is over, at least at reasonable prices... And that affect Medved too - you cant do that with CFLs

I can't imagine anyone would want to steal light bulbs. But it makes sense the left hand thread are more theft resistant. If someone were to try to unscrew the bulb they would be tightening rather than loosening the bulb. Plus if someone were to remove it, it will not work on the sockets at home.

Left-hand thread lamps are indeed used in public places where theft could be a problem. Interestingly, LHT lamps are exempt from lamp bans here in the USA. It would be interesting to see how hard it would be to find fixtures or sockets that take left-hand thread lamps. I seem to remember looking for them a while ago, and could not find any LHT sockets whatsoever. After all, if the average person could buy LHT sockets, then LHT lamps would again be valuable to steal. Kind of like "security head" screws. Now you can just go to the hardware store and find bits that fit security head screws, so they aren't secure anymore.

So far, I've never seen a LHT CFL.

You can buy in hardware store tools for normal screws, and modify them to open security screws. No big issue

Never seen left thread lightbulbs, but there is something else left threaded here : LPG gas containers here are left threaded where the pipe is connected to them

Our LP containers are also left-hand threaded!

Our LP containers are also left-hand threaded!

With the left vs right hand thread are a safety measure (one from many) to difference pressure tanks with combustibles vs oxygen, so nobody could accidentally swap hoses when connecting them to the torch (that would lead to very nasty accidents, mainly when the acetylene is involved...).
However I never remembered what is what...

Wouldnt it be simpler to use different diameter threads instead ? This won't have possibility of confusion wen you think you are tightening the connection while in fac you are opening it

Using a bulb with a cap many people won't be able to use is a fairly good disincentive for stealing them, it does happen. When I visited one of the cultural centres on the outskirts of Nairobi I saw that the table canopies in the grounds all had ES fittings which are not common in Kenya apart from wall lights and possibly enclosed ceiling fittings, the pendants are all B22 (BC). it seems no-one uses table lamps etc.. Even in this case (at Bomas of Kenya), the bulbs were brought when you were there and removed afterwards!!

When I was little it was usual to leave a bulb in the entrance hall when moving house. This wasn't even a particularly poor area! These days we wouldn't even think about doing that, in fact it's usually expected by the landlord/purchaser that the lights should be working. How times change!


BG

I have a few left hand thread bulbs, they look like normal bulbs in every way except for the reverse threads.

I have a few left hand thread bulbs, they look like normal bulbs in every way except for the reverse threads.

I remember in Philips catalog way back when they offered CFL theft prevention pin, when CFLs were good $10-15 ea. 
I think the idea of LHD lamps isn't necessary to prevent removal as much as making them unsuitable for other use, thus making them unattractive to steal. 

With CFLs, I think pin-based PL-Cs serve that purpose just fine. 

I think they are the "security" lamps, those that only fit into certain sockets/fixtures.

 I have heard that Left Hand Thread E26 lamps were used in traffic lights in the United States. And, yes, its was a disincentive for theft. I am actually seeking a sample of such a lamp.
   Here in Tasmania, when I was young and (RHT) E27 was relatively uncommon it was used for this type of purpose. Small mercury lamps had B22d-3 caps, (Three Pin) to prevent accidental placement into B22d-2 sockets connected directly to the low impedance mains.
    So our situation was similar to what BG 101 describes in Kenya. These days E27 now constitutes about 20% of all domestic sockets. Somewhere I have a theft proof C.F.L made in Italy, once you have screwed it in (E27), you remove a key and the threaded part of the cap is free to rotate, so no amount of screwing will get it out until the key to lock the threaded shell to the inner cap is inserted again!