Wednesday, May 16, 2012

Before there were fuses!!



The First electrical systems Did not have fuses?

I recently came across this ceramic electrical distribution block. Today this would be done with a sub-panel. Here you can see three cables feeding two ceramic blocks. The enclosure was a handmade box lined with what appears to be asbestos.  Off of the two porcelain block are 4 two wire circuit. All of the wiring was Knob and Tube style cloth covered conductors. This home was built in the early part of 1900 when electricity was new.  





Here is a close up picture of one of the blocks. There was an over current protection built in. If you look closely you can see a thin wire that jumps between the screws. This is an early attempt at fusing the circuit. The jumper wires look to be made out of a metal other than copper. I think it is either lead or aluminum but cannot be sure.  This wire should be the weakest link in the circuit and should blow before anything else in the circuit burnt up. 




Fuses were added to these ceramic blocks with standard Edison socket. The fuses were standardized and rated at 15 or 20 amps for house circuits. It is hard to believe that this old and very unsafe system was still in operation in 2012. 

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1 comment:

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