Switches and the termonology industry has created around them

Hi my name is Jimmy.

      It has been my good fortune to work in industry as a technician for most of my life. My father was an industrial technician. In those days they were called maintenance men. As with any family of five in the late 50s and early 60s he had to take on side jobs to make ends meet. He called it moonlighting. He would go out to another company and preform repairs for them. In those days things were a little more simple and the companies did not mind if he brought me along. So by the time adolescence was approaching my industrial training had begun. At 14 I was helping him install components like solenoid valves and switches for automated processes. This profession has been mine from that time to now as a retiree. This has all been said to qualify my knowledge to anyone who might doubt it. There is no formal education in electrical engineering beyond a few community college courses.

    Switch terminology is like any other. The terms are used by people in that field and might have a Websters definition that has no bearing to that use. Then there is the ratings and specifications that can be confusing. Lets talk about terminology first. Like Poles, Throws, Momentary, Maintained, Rotary, Drum. What does it all mean?  

Poles  Lets think of a pole for a minute. Now the pole has a wire hooked to one end. Suppose the pole can be pushed to one side that brings it into contact with a point that has a wire attached to it. That is a single throw. Now suppose the pole can be pushed back the other way where it connects with another point with a wire. That would be a double throw.  So the above description is of a single pole double throw device.  But if the switch can only connect in one direction it is a single pole single throw.  Double pole and triple pole are actually two and three switches in same housing. So the number of poles could be related to the number of isolated circuits within the same housing. 

   In the next posting I will talk about the number of positions and and how it relates to poles and throws.

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