Willis Lamm's Traffic Signal Collection (And Street Lights Too) Clicking on a picture will bring up a larger view in a new window.   General Electric (GE) Form 79SO Series Street Light

Early street lights evolved from lanterns to gas lamps to high voltage arc lamps to incandescent lamps. Generally light was cast in all directions either through various styles of glass refractors or by radial wave reflectors. It helped pedestrians and downtown shopkeepers when street lights lit up everything nearby. However when street lights found their way out into residential neighborhoods that had narrow lanes for streets, the relatively uniform spread of light could be annoying for residents whose houses were placed fairly close to the street. One of the ways in which light could be better directed up and down the street, but be minimized with respect to areas beyond the street's pavement, was the Form 72SO, often called an "admiral's hat" or "crescent moon" street light. The Form 79SO in the collection is the all aluminum version of the original ceramic bodied luminaire. In some respects the Form 72SO was a precursor to the modern day cutoff luminaire since light is primarily directed by the design of the reflector. Records suggest that the later version of this design was also cataloged as a Form 7980.

Components of the Luminaire

Some of the early GE luminaires have no brand markings. Here are some photos that may help with identification.

Mounting hub - round with 2 flat sides as opposed to the hex shape found on most luminaires. Conductor entrances have solid copper centers. Cables connect to the ends of the insulators. View of main reflector. Latch wires look somewhat like L-M latches.

Interior view of the series socket. Blades close when socket is removed to keep circuit alive. Cast aluminum tab for safety chain. Some models used small eye bolts instead. Cutoff extensions are attached by round head screws that screw into threaded clips.

Typically one reflector cutoff extension was longer than the other. For installations that were vertically "plumb," the longer extension would be on the pole side of the lamp and the shorter extension would allow light to travel to the other side of the traffic lanes. Some of these luminaires were mounted on arms that held the heads slightly tilted towards the street, usually if the utility poles were set back from the roadway. In those instances the reflectors would sometimes be installed "backwards" with the longer extension facing the opposite side of the street to limit light from extending much beyond the far curb line.

All the components laid out.

GE Product line from the 1940s

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GE Form 110SO Street Light