Hello,

I am new here and it is good to find a site dedicated to the appreciation of luminary devices

Please help me to identify the following:

I am trying to identify a specific commercial-grade light bulb, and the exterior fixture that it is presently housed in, both of which I am including pictures of. I believe this is a NEMA-head Dusk-to-Dawn Mercury Vapor Fixture, yet it is housing a Low Pressure Sodium bulb. When the lamp is turned on, it emits a dim red/pink light and within a few minutes it turns into a bright orange-yellow.


I am also interested in whether this bulb has a plug-type or screw-type base for socket insertion.

Additionally, I am interested to learn where these fixtures may be purchased.

It should be noted that the bulb and fixture in the pictures are approximately 25 years old.

Thank you very much for any assistance you can provide!

Hi, and welcome to Lighting Gallery! I hope you'll enjoy that website. 

About your fixture, the Low Pressure Sodium lamp has a bayonet base (a By22d if I'm right). NEMA LPS fixtures are uncommon, that's a cool find!

Amercian Electric and ITT made them up to the 80s. American Electric Lighting had them listed in 35W and 55W until last year! Chances are a NOS fixture will pop up one day on eBay. Craiglists may also hide one.

Hope this helps!

Vince.

Very cool!

I have one of these that I found NOS on eBay.  I had seen a few in use around where I lived and had searched for one for 10 years.

They were made by American Electric/ITT/T&B/AEL up until 2008.  Their ballast is a dual wattage L70/L71 HX-NPF for 35/55 watt LPS lamps and they use a bayonet base socket.  Their reflector is attached by NEMA clips and is extra tall to allow the use of standard height 12" bucket refractors.  All that I've seen are 120 volt.  I've noticed the ballast on mine has an extra terminal.  I'm not sure if that is a different tap used for running 55 watt lamps in it.

Replacement lamps can be expensive but do pop up on eBay.  Replacement refractors are made by companies like Formed Plastics, but a 12" refractor from nearly any common yard light will fit.

The NEMA head itself is a common style manufactured by a number of companies over the years, and has been used with various wattages and light sources, including incandescent, mercury vapor, low pressure sodium, high pressure sodium, metal halide and incandescent.  175 watt mercury vapor and 70-100 watt high pressure sodium are probably the most common configurations.  The LPS-specific parts of this particular fixure are the ballast, socket, extra-tall reflector and lamp support.  I had also seen similar fixtures made by Norelco.

I hope this information is helpful and satisfied some of your curiosity.  Good luck finding one.  They are super rare, but if you keep looking, I'm sure you can find one.

Strange that there is no sodium migration in this LPS lamp as it is too long for being suitable for base up operation. Long LPS lamps suitable only for horizontal burning position.
This lamp seems to be very high quality as LPS have an avarage life of 18,000 hours (Unlike HPS that have 24,000 hours).
LPS lamps are more prone to premature failures than fluorescent lamps and have one failing mechanism that fluorescent and HID don't have: End of gas life.
Quite simply: the argon in the argon-neon mixture are absobed by the sodium resistant borate glass of the sodium tube. If all the argon from the argon-neon buffer gas consumed, the ignition voltage will rise and the lamp will fail to ignite. This problem is more common in lamps that have a sodium migration such as long lamps that are burned base up.

55 watts is the highest wattage that can be run vertically base up.

55W LPS lamp length is 425mm or 16.732" (inch). Isn't this length too long for the lamp to operate in base up without sodium migration?

Here is the orientation information off Philips's website...
For 10, 18, 35 and 55 watt LPS: Base Up +/- 110°
For 90, 135 and 180 watt LPS: Horizontal +/- 20°

The 55 watt LPS lamp seems long, but you have to remember the 180 watt LPS lamp is over a meter long.