Switches For Dummies

To clear up voltage ratings on switches

Most manufacturers print a voltage rating on the switch at the factory. Due to limited space, they normally print the highest voltage at which the switch should be used for on a continuous basis under normal conditions. Now this is a very controversial statement because not everyone's normal is the same. Lets just say dust and debris not visible, Moisture not high and no extreme temperatures that would affect the insulation or mechanical properties of the components.

It needs to be said here that the switch is good for any voltage below that rating all the way to zero volts. Under the same conditions no matter whose definition of normal you use. So if the connecting device says 600V on it it is also good for 12 VDC or 24 VDC or 125 VAC and 250 VAC and so on at any value between 0 and 600 AC or DC.

To clear up Amperage ratings on switches

That does not mean that the amperage rating on the switch applies to all voltages and types of current. As a matter of fact it only is supposed to apply to the voltage and type stated on the switch.

If you apply ohms law to voltage and amperage it would indicate that if the voltage were half the amperage could double. I Current (amperage) = Voltage divided by Resistance. Changing the voltage of the circuit does not change the resistance. However that is not true with alternating current. So you can not use ohms law to determine the amperage value for AC. And there are many more mechanical factors for both DC and AC that have profound affects on arching outside the scope of this discussion. Like materials,speed, pressure, sliding, bouncing, and so on. So it is very important to reach out to the manufacturer of any switch for amperage ratings for the voltage type and levels you need in the circuit.

Maintained and Momentary explained

A Maintained switch is noted several ways in different industries On Off On or Latched or Latching or Locking It is going to Latch Lock in position you or someone else places it. Used for non jogging operations like pumps fans or lights A momentary switch denoted in several ways also is (On) Off (On) or Resetting or automatic reset or springing This term means it will return spring reset to a position (usually off) when you release it. For jogging operations like lift hoist winch or door

What does Pole and Throw refer to

Consider pole to indicate the number of Isolated (individual) Inputs. Throw would be the number of outputs for each pole. Do not confuse the throws with positions. Any single throw switch can only have 2 positions On Off if you think about it. But a double throw switch can have 2 or 3 positions. If a double throw switch has 3 positions it is sometimes referred to as On Off On, and will probably have off as one of the positions. ( usually in the center ). If a double throw switch has only 2 positions then it will always have the input connected to one of the outputs and will not have an off position for all outputs at same time. This is sometimes referred to as On On.