NO or NC? Let’s Clear the Confusion!
As a manufacturer of magnetic switches, we frequently encounter a common question from our customers: Which switch is NO, and which is NC? Surprisingly, this simple classification often leads to confusion.
Imagine this scenario: A customer requests an NO switch, and we dispatch it accordingly. However, upon receiving it, they insist it’s actually an NC switch! Does this mean we, as manufacturers, misunderstand our own product? Or is it possible that the customer, despite years of experience using these switches, sees things differently?
Let’s dig deeper into this issue.
We all know that NO stands for Normally Open and NC stands for Normally Closed. The confusion arises because manufacturers and customers approach these terms from different perspectives.
How Manufacturers Define NO and NC
Manufacturers classify switches based on the raw materials used in production. If we use a NO reed, we label the switch as NO. Similarly, if we use an NC reed, we call it an NC switch. This method keeps the manufacturing process straightforward—sugar is sugar, and salt is salt. Simple, right? But then, why does this confusion persist?
How Customers Perceive NO and NC
For customers, the priority isn’t the internal components but rather how the switch functions in their application. They focus on the final outcome. Think of it like cooking—a chef might use sugar and salt in a dish, but if the dish tastes spicy, that’s how the customer describes it.
For example, a customer wants a switch that turns the light OFF when the door is closed—its default state. When the door is shut, the reed and magnet are close together, and no current should flow. Logically, the customer assumes they need a NO switch. However, here’s where the tricky part comes in.
The Reversal Effect of Magnetic Switches
When a magnet comes near a reed switch, the reed’s state reverses—NO becomes NC, and NC becomes NO. So, when the door is closed and the magnet is near, the switch is in a reversed position. For the customer to achieve their desired NO function in this position, the underlying reed must actually be NC.
Since we, as manufacturers, use an NC reed, we label it as an NC magnetic switch. However, customers, focusing on the final function, refer to it as an NO magnetic switch.
Avoiding Confusion When Ordering
Next time you order a switch, clarify what you mean by “normal condition.” Are you considering the switch’s state when it is near the magnet or when it is away from it? Understanding this distinction will ensure you receive the correct switch without any surprises!
Recent Comments