Old GE streetlighting equipment

[power-history]

This ad from 1957 shows an assortment of streetlighting auxiliary equipment, and an installation of fluorescent streetlights. Fluorescents were quite popular in that era, but apparently they were soon overtaken by mercury vapor. I've read, though, that they're being tried again in a few places.
http://long-lines.net/other/electric...04-08/091.html

[BigClive]

There's a street nearby that uses fluorescent streetlighting. It uses the modern U-tube style of lamp.

[power-history]

Yes, I think that's the type being used in most of the recent installations. The resurgence in fluorescents seems to be strongest outside the U.S.

The original fluorescent streetlights used long straight tubes in larger fixtures. Here's an ad for Holan lifts showing installation of a giant luminaire in Indianapolis, Indiana:
http://long-lines.net/other/electric...01-21/115.html

I think these fixtures were largest ever made. Some of the big fluorescents even had cooling fans!

General Electric made a line of fluorescent tubes having grooves or indentations all around, to increase the light-emitting area for a given size of tube. I think the brand name was "Power-Groove" or something like that.

Here's another GE ad showing an urban installation of fluorescents:
http://long-lines.net/other/electric...05-13/105.html

And here's one from Pfaff and Kendall:
http://long-lines.net/other/electric...05-20/054.html

[BigClive]

And here's the domestic version which apparently offered seven hours of warm bright light for only a penny. (More like 4 pence now assuming good power factor and a 36W tube.)

http://uk.youtube.com/watch?v=fuRC-nqO1Bo

A very "vintage" television advert.

[power-history]

Thanks, that's a great ad! It's interesting for a couple of reasons: first, because the fixture is surprisingly modern looking, with the exposed, "floating" tube and asymmetrical mounting. And second, because I didn't realize that the Mazda brand name was still in use that late.

I'll add the link to my site.

[RWD]

I worked several of the old 6.6 amp street light systems out west. Sometimes retiring them and sometimes fixing them. They were series wired and had a little fuse that would allow current to flow past if the bulb went bad. Easy concept after someone explains it to you but the idea of variable voltage fixed amps could be a killer to a newbe. These systems could have anywhere from 2400V to 50V but maintained a constant current of 6.6 amps. Many of the runway lighting systems I worked on had the same system. I don't know what runway lighting uses now. I'm sure they have moved on from the old system by now.

RWD

[power-history]

Series streetlights are a really interesting technology - the whole idea of constant current and varying voltage is "backward" from the the parallel circuits that are more common in electrical work.

The heart of the system was a constant-current transformer. It had one winding that was physically moveable - it could slide up and down along the core and was attached by cable and pulley to a counterweight. As the load on the transformer fluctuated, the magnetic force would push or pull the movable winding until the force was balanced by the counterweight, thereby adjusting the voltage to keep the current at a constant 6.6 amps. There was a pole-mounted version (see http://long-lines.net/other/electric...04-08/091.html) and also a larger "substation" type.

The fuse devices that you mentioned were called "cutouts" - I think the slang term was "pills" because of their appearance. They were actually the opposite of fuses or cutouts as we usually think of them. They were installed in parallel with each lamp socket, and as you said, their purpose was to short out the socket when the lamp burned out, to keep the circuit operating.

A cutout was an aluminum disk coated with a thin film of aluminum oxide, which is an insulator. When the lamp was operating, the voltage drop across the cutout was small and the cutout had no effect. But when the filament opened up, the entire circuit voltage was across the cutout, and this punctured the oxide film so that the current flowed through the aluminum disk and bypassed the socket.

[Stinger]

We did a reconductor job about 4 years ago in Winchester Mass, We took down an old arc street light transformer. I do not know what they did with it, but hind sight being 20/20 I should have taken a pitcure of it to hang in our hall by the display case of old line tools and equipment. I am 61 and I know that transformer was older than me. There are still some small towns here in New England that still have the old incadesent light bulbs with old flat round reflector painted white on the underside.

[BigClive]

Hmm, history repeats. Modern LED lighting systems tend to operate on a constant current system too, with up to about 10 LEDs in series on an electronic current regulated DC supply.

The little shorting devices that kept the other lights in the older series string arrangement are still in use. Take a look at a series string of traditional Christmas lights and you'll see that just below the filament and right up against the glass bead is a little loop of wire. There's a coating on the wire that insulates it from the filament leads until the lamp fails and the voltage rises to the full mains level across that open circuit until the insulation on the little wire breaks down and it shunts out the lamp.

[power-history]

That's interesting info! I've played with LEDs a little - just enough to see how differently they behave versus incandescent lamps as the voltage/current is varied.

Are LED Christmas lights becoming popular in Scotland? They seemed to really take off in popularity in the US last year. I like the pure, saturated colors and the way the blues and greens are as bright as the reds and yellows, unlike with incandescents. And of course the energy savings are pretty substantial. The only thing I miss is the warm color of the clear incandescents; the white LED is really a bluish-white. And it remains to be seen how durable the LED sets will be - especially the consumer versions. I've heard some unfavorable reports in that regard.