Back to Docking Drawer FAQs

How Do “Normally Closed” and “Normally Open” Switches Differ?

Q: What is a Safety Outlet Switch?

Magnetic switches (non-contact, activated by a magnet in close range) are included with Docking Drawer’s Safety Outlets, and are triggered by the position of the appliance garage door. When the door moves, the switch signals power to turn on or off based on whether it is a Normally Open (NO) or Normally Closed (NC) model.

Q: What Do “Normally Open” and “Normally Closed” Mean?

These terms describe the resting condition of an electrical circuit—something that can feel confusing at first.

Normally Open (NO): At rest, the contacts are apart, so the circuit is broken and electricity doesn’t flow.

Example: A doorbell. Until you press it, the circuit is open and nothing happens. Press it, the circuit closes, and the chime rings.
Normally Closed (NC): At rest, the contacts are touching, completing the circuit so power flows.

Example: A refrigerator door switch. When the door is shut, the switch is pressed, keeping the light OFF. Open the door, the circuit opens, and the light turns ON.

👉 Quick Recap:

NO = Open circuit at rest → no power
NC = Closed circuit at rest → power flows

Q: Which Switch Type Should I Choose?

Normally Closed (NC): Circuit closed at rest → power ON. When the garage door is shut, the switch opens → power OFF.

Select NC if you want the power cut off when the door is fully closed.

Normally Open (NO): Circuit open at rest → power OFF. When the garage door opens, the switch closes → power ON.

Select NO if you want the power to turn on as soon as the door opens.

Wiring Diagrams

For installers or those wanting more detail, see our wiring diagrams for both NO and NC Interlock Limit Switches.

Normally Closed (NC)