I'm not an electrician, but I have a basic understanding of circuits

I had bought a switch that was labeled NC, and when it was unpressed, the light connected to the switch turned on

When it was pressed, it turned off the light

I'm looking at this product right now https://edwards-signals.com/index.cfm?pid=69&level=48

and it says "push to open" and "push to close"

does "push to open" mean the same as NC?

Logically it seems to make sense that way, but the different terminology is tripping me up, and I just wanted to confirm before making a large purchase

  • \$\begingroup\$ push to open == don't push to close, aka normally unpushed, normally closed \$\endgroup\$ – dandavis Jul 6 '17 at 4:26

A switch is able to carry current when it is closed --- that is, when the two contacts are touching.

If you put the switch in series with a light bulb, for example, the switch needs to be closed to allow current to flow through the light bulb and light it up.

NC stands for normally closed. That means the normal state of the switch is closed, and it will be opened (breaking the circuit) when it is activated (for example, by pushing a button).

So yes, "push to open" is the same as NC. FWIW, "push to open" is not standard EE jargon --- possibly it's more common in some specific sub-field like the industrial controls that seem to be the market for the website you linked to.

  • \$\begingroup\$ perfect thanks! yeah it confused me because every thing else had "NC", and they used "push to OPEN". maybe I should send them a support request to change that :) \$\endgroup\$ – A O Jul 6 '17 at 5:15

The switches on the top are open, as in open circuit.

The switches on the bottom are closed, as in closed circuit.

Press to Open means open the circuit, breaking/interrupting it and preventing it from conducting.


simulate this circuit – Schematic created using CircuitLab

does "push to open" mean the same as NC?

In this case, Yes.

  • \$\begingroup\$ You might want to add that the right two are usually push-buttons and not switches (or is that just my interpretation?) \$\endgroup\$ – Arsenal Jul 6 '17 at 7:35
  • \$\begingroup\$ @arsenal makes no practical difference in this situation. \$\endgroup\$ – Passerby Jul 6 '17 at 18:05

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