What is a Normally Open Switch And How it Works

I published 2 posts about power wiring / 3-phase wiring and in both posts, I talked about the normally open switch and I used it in my diagrams. There will be many peoples who don’t know about that what is a normally open switch or what is a NO push button switch and how it works.

To make these question off, I am gonna write this post and disuse only normally open switch in this post which we better knew by their short name NO which mean normal open switch. However, my next post will be about the Normally close switch or NC push button.

What is a Normally open switch and How it works?

This switch is a momentary switch which is an internally open electric circuit in the normal state just like a doorbell switch or we can say that the doorbell switch is a good example of a normally open switch. Whenever we push this switch, it makes contact with the electric supply or makes a close electric circuit. We can also be called the normally open contact switches.
There are some images of a normally open push button switch and its symbol for better understanding.

normally open switch symbol

Uses of Normally open switch / NO push-button switch

We can use it for many things where we required a NO push button switch but the big use of this switch is in power wiring / 3 phase wiring where we use these switches for the magnetic contactor to switch on and off the contactor. We use these switches in the power electrical panel board and also we use them in power factor improvement electrical panel, in short, we can use it for anything where we required.


The reason for this post publishing is only that I want to learn students clearly and understand everything about electrical technology because I am also a student. I hope now your concept will be clear about the normally open switch and its working and uses.

3 thoughts on “What is a Normally Open Switch And How it Works

  • February 18, 2016 at 4:45 pm

    IN SHA ALLAL jald hea mea post karo ga. mean ne it diagram post kya howa hai, app website par deak sakte hai

  • February 19, 2019 at 8:56 am

    Please show me step by step processes in connecting DOL starter to 3phase motir


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