NO or NC? Let’s check it!
Hi friends, being a manufacturer of Magnetic Switches we constantly face a question from our customers. Which is a NO switch and which is an NC switch? and this at times gets very confusing.
It even leads to trouble when a customer asks for NO switch and we dispatch it. But surprisingly it turns out to be an NC switch.
So why this confusion? Is it that although being a manufacturer are we not aware of what we are manufacturing? or the customer who is using the switch for a long time, doesn’t know about it?
Ok, so let’s dig a little bit into this, though the terminology NO and NC is not an uncommon thing. Still, the confusion prevails.
NO – Normally Open and NC – Normally Close as we all know it.
Technically saying whenever this confusion arises, neither the customer nor the manufacturer is wrong. It’s just the way how both are looking at things. As a manufacturer, we look at things the way they are being used in the manufacturing process. So if I use a NO reed, I call it a NO switch, and if I use an NC, then I call it an NC switch. It’s as simple as that, no confusion, as per the raw material used we name it. This way the manufacturing process get’s quite simple, sugar is called sugar and salt is salt.
So if it’s that simple, then why this confusion?
Ok, so I’ll tell you now, what happens is, as I said sugar is sugar, and salt is salt, but the customer is not interested in the ingredients. He is concerned about the final taste of the dish. So even if adding sugar and salt, the dish get’s spicy, it would be called spicy, it’s just that simple.
A customer eye’s the result, rather than being interested in the ingredients used for making it. Quite fair, why would he want to complicate things for himself?
If he wants when the door is closed which is the ideal condition, the light should be OFF. Quite fair.
So it means when the door is closed, both reed and magnet are in close proximity, and the light has to be OFF, there should be no current flow in the circuit, now this is possible by a circuit where there’s no current flow. So the customer is looking for a NO switch, as for him the ideal condition is, that the door is closed and both reed and magnet are in close proximity.
As we know that getting a magnet near the reed, the position of the reed reverses, NO becomes NC and NC becomes NO. So for the customer’s normal condition when the door is closed and the reed and magnet are close to each other the reed is in reversed position. For this position to be NO the basic reed has to be NC, so it can reverse.
Now since we are using an NC reed here, as a manufacturer we call it NC magnetic switches, which our customers refer to as NO magnetic switches.
So the next time when you order your switch, make sure the normal condition that you refer to, is it by considering the proximity to the magnet or not?