1 NO Block vs. 2 NO Blocks

[Thehopguy]

I am looking for a simple ON/OFF selector switch for a Master Power and 2 pumps on a control panel. I found this 2 Position Selector switch with 1 NO Block from ebrewsupply: http://www.ebrewsupply.com/2-way-1-no-contact-switch/

and this 2 Position Selector switch with 2 NO Blocks from Auber.

What is the purpose of having 2 Blocks as opposed to 1 and which is best for my needs?

 

[sam]

The blocks just give you options. You can get extra blocks, mix and match them, and stack them on the back of the switch.

Let's say you wanted a red LED to light when a switch is off and a green LED to light when the same switch is on, you'd want that switch to have 1 NC and 1 NO block. The red LED would be wired to the NC block and the green to the NO block. When the switch is off, the NC block would light the red LED. When the switch is on, the NC block would open to shut off the red LED and the NO block would close to light the green LED.

Take a look at how Kal wired up his control panel. You'll see the blocks on the back of the switches and that some of them aren't used. The diagrams and pictures in Electric Brewing Supply's guide help too.

If you just want a simple on/off for you pumps and power, you probably only need one NO block on each switch. For my system, I didn't have a need for 2 NO blocks on any of my switches. I did need 1 NO and 1 NC block on all of my pump and element switches; I use the NC blocks on those switches for my safe-start interlock circuit.