Cave Bulbs

[Scott]

Last Saturday, I wound up visiting 7 Caves, a sort of cheesy tourist thing near Chillicothe,Ohio. The caves were illuminated with ordinary-appearing bulbs, but the wiring appeared both old and had a lot of open-contact cleat sockets, which,to me, seemed a sloppy and dangerous way to handle 120 volts in a damp environment where a lot of people visit. Upon looking at one of the fixtures, I noticed the bulb said "34 volts"..I'd like to get a couple of these for some projects I have in mind,and for my collection of weird things. These, in appearance, are everyday Edison base bulbs.
  I suppose I could've asked there, but I didn't. Anyone ever heard of these, and if so, where could I get a couple?

[Chris W. Millinship]

Well I don`t know about 34-volt ones, but a couple of years ago I bought some regular size and shaped screw base bulbs here in Britain, that were rated 12volts, 50watts and fit a standard screw socket. They were sold in an auto-accessories shop and intended for 12v battery powered vehicle inspection lamps. I don`t know whether similar things are for sale in the US but you might like to try a local auto-accessories shop, or perhaps a car repairs garage, if 12volts (or perhaps even 24volts?) is suitable for your projects.
I also believe regular size bulbs are made in 50v-ish rating for specialist uses but I don`t know where to get those.

Hope this helps?

-chris

[Scott]

I have a couple of the 12 volt kind, plus a 6 volt one in the shape of a "regular" Edison base bulb,but I'd like to have one of the 34 volt ones for my collection of weird things. Packrat-style collector.

[James]

Hi Scott,

34 Volt bulbs are the type usually used on some older trains and tramcars for internal lighting, quite often they are wired in huge series strings and operate directly from the overhead wire or electrified rail which is in the region of 400-800V depending on the system.  There are two kinds of bulbs, some are just regular low voltage types but others have an aluminium oxide shunt in them, just like miniature christmas tree bulbs so that the circuit stays lit if one filament burns out.  The regular types are often wired with a neon indicator in parallel with them, so when the filament fails and the whole string goes out, the voltage rises and the neon will light up only for the bulb which has burned out - thats just so you dont have to go replaceing all the bulbs to find out which one is dead.  GE and Sylvania still make a wide selection of 34V bulbs from 15W-150W you should be able to get them through any big lamp wholesaler, they are standard bulbs listed in the catalogue.  Or just ask your local rail depot if they'd let you have a couple

For Chris and others in the UK, we have 65V and 85V train bulbs which run on a similar system.  These are mushroom shaped and have a bayonet base with 3 pins to discourage pilfering and are marked British Railways in big lettering.  Sometimes they may have a left hand threaded screw base instead but they are more popular in USA, again this is to discourage theft because even the dimmest of thieves will realise something is wrong when the bulb doesn't unscrew the right way!  I've heard of the LH threaded bases being used in hotel rooms as well, where bulb thefts are apparently a common occurrence!


[This message has been edited by James (edited September 06, 2000).]

[Scott]

   I wonder how many dim thieves have cut their hands trying to unscrew a left-hand thread bulb as if it were right-hand? More than a few, I bet. I read an article about subways in New York City having trouble with bulb theft-not that the cost of the bulbs was that much, but passengers didn't like dark corners and things. Their solution sort of went the other way. They put high voltage bulbs in-normal Edison base, but either 240v or 277 v. Pretty dim on 110 volts. I don't know if it worked or not. I'll have to order them-the nearest railway depot is about 100 miles from here.I could write to the tourist place and just ask them if they'd sell me one. Sometimes, the direct approach works.

[Earl Wildes]

I work with the Northwest Railway Museum, and we buy 32 and 72 volt bulbs from the local supplier.  You very often have to buy a full case, but they are available.