Self-Ballasted Mercury Vapour Lamps

[Ross]

Firstly, thank you Chris for your account of the repair of your red carbon fillament lamp.  Fantastic !

My query relates to much more modern matters.  Is it still possible to obtain self-ballasted mercury vapour lamps ?  As a child I remember seeing these in street lighting and in some shop display lighting.   The mercury arc current was limited by a series tungsten fillament in the outer glass envelope.  This resulted in instant "tungsten" light at switch-on, which gradually shifted in colour to the usual mercury vapour colour as the arc tube warmed up.

[James]

Hi Ross,

Self-ballasted mercury lamps are indeed declining in popularity, but they are still in production!  From 100W to 1250W, you should be able to obtain these via a good electrical wholesaler from from any of the main UK brand names Philips, Osram, Sylvania or GE.  Of interest to lamp collectors are often the lamps made by Iwasaki Electric of Japan, they are unique because they offer these lamps in both phosphor-coated and clear glass bulbs, so you can clearly see the ballast arrangement inside.  If you should wish to order these its probably best to go direct to Iwasaki, they have a website at www.iwasaki.co.uk

James

[Ross]

James,

Fantastic - thank you for the information.  I am very intrigued by the clear version of the lamp - I'll have a surf around.

Many thanks.

[The LED Museum]

I believe Sylvania may still make these in the form of large reflectorized sunlamps. I find one or two of them a year at flea markets, usually for under five bucks, and I have yet to find a dud.

They look like large PAR type reflector bulbs, but are made of thinner glass and have a protruding button on top that holds a metal support for the arc tube inside.  This type of bulb is rated 275 watts, 110-125 volts (AC only, according to the label). Medium screw base.

When started, they output a whiter than usual "filament" spectrum for a moment, then the mercury tube starts to kick in.  As it warms up over the next few minutes, the tungsten spectrum dies off and the mercury spectrum becomes dominant.  Heavy UVA and UVB output; quite nasty to the eyes for close exposure. (In other words, don't hold it up to your face and stare into it or you'll be sorry about two hours later).  

As for labelling, there is none on the base. The top surface of the bulb is inkstamped:

SYLVANIA SUNLAMP
110-125V AC ONLY 275W
34 WARNING ULTRAVIOLET - READ CAUTION NOTICE

[Chris W. Millinship]

Those lamps sound interesting- I think I have seen pictures of them (I know the bulb shape you describe) but don`t yet have any here in my collection. Discharge lamps have been grabbing my attention more and more recently, such a fascinating aspect of electrical lighting so please forgive me for being so direct but: do you have a spare there you would be willing to sell? If so, please shoot me an e-mail (bulbmuseum[at]ntlworld[dot]com).

 


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[James]

Hi Chris - you can still get these lamps brand new in Europe, although they are scarcer in USA now because they were banned there in the 1980's.

Here you can buy the Osram Ultra-Vitalux or Philips MLU type from any good lamps wholesaler and they will be in 240V rating which might suit you better.  Or keep an eye out on Ebay - a few days ago I saw six of the Philips MLU300 crop up there for just ?5.

American types are known as the RS Sunlamp and there are always a few of these in GE or Sylvania brand on Ebay USA.  Sylvania's have the RT bulb shape which Craig mentions, like an ordinary reflector but with a supporting dimple at the front.  GE's used plain R shape glass, as do the Osram and Philips lamps over here.

Best of luck in finding one!

James.