Question about switches...

I am very new to electrical projects. Please be nice. Does it matter which side is positive or negative on a switch?

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DrBrown7 years ago
 If the switch makes and breaks high amperage DC contact, it matters alot. An extreme example would be ignition points in an old engine. Polarity will deposit some of the contact pad on one side onto the contact pad on the other side. Eventually this will make one pad shrink an concave while the other grows and convexes, sort of like arc-welding. For this reason some contacts are silvered on one pad to slow the deposition process. Wired in reverse, the naked pad would soon burn away. Examples would automotive, electric wheelchair, and golf cart switches. Except for magnetic contactors and motor starters, most AC switches do not have this issue. 
NachoMahma9 years ago
. Unless they have an LED indicator or some such attachment, mechanical switches don't have polarity. For high current handling switches (motor starters, &c), it can make a difference which side is wired to line and load, but even that is not a polarity problem.
didnt i say that? and beware: most illuminated switches use neon or incandesent lamps, not leds. i suppose its simpler.
> didnt i say that? . Sorta. I worded it a little different to give a different perspective. Not trying to steal your thunder, just give a slightly different explanation that s/he might be better able to grasp. . It seems to bother you more than it should. In the future I will try to say something like "As tech-king pointed out, ..."
thank you. perhaps it bother me more than it should, but i make most of my posts in the school library, and the computers are slow and buggy, making me wonder if the comment actually made it to instructables or not.
Goodhart9 years ago
Normally a switch breaks the "positive" leg of a circuit. That is, for instance, the positive line form a battery, on its way to a light bulb, is interupted by a switch in order to control it (turn it on or off), therefore being on the "positive leg" a SPST switch does not matter which way it is connected. A SPDT switch doesn't matter concerning the direction, but it does matter which poles are used. One is switching between two poles, and is either hooking it up as On, or OFF and switching to the other state. Now, if one hooks one leg to the one side, and one to the other and nothing to the common pole, the switch will not work.

If you scroll down through the illustrations of These switches it may become clearer as to what I am speaking of.
FROM a battery....... not form - sorry
tech-king9 years ago
i have a feeling you have an exellent counter-argument. 1) assuming you didnt buy a switch with an internal led, really. 2) exeptions: HV air switches freon switches (although there is no real risk from cross wirring circuit breakers (only to make it obvious wich way is on and off)
tech-king9 years ago
absolutly not.