🚀 go-pugleaf

History-- series streetlamps


Old-style incandescent streetlamps were wired in series.  I always 
wondered how such a system could work. I finally learned the method 
which kept the lights on when a bulb burned out:

One hundred 120-v bulbs were wired in series and connected to a 12,000 
volt line.  Above each lamp socket was a pair of spring-loaded 
contacts separated by a piece of waxed paper.  If one bulb burns out, 
the voltage goes up, the paper arcs through and burns away, forming a 
short circuit.  The remaining bulbs get 1% more voltage.  This 
ingenious method saved wire, transformers and switches.  The 
maintenance crew had to be diligent and not let too many bulbs burn 
out!

--

Frank
reid@gold.bacs.indiana.edu