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How Do I Wire an Emergency Stop into My Actuator System?

An emergency stop (E-stop) immediately cuts power to all actuators in the system. Adding one is a best practice for any application where unexpected motion could cause injury or equipment damage.

How an E-Stop Works

An E-stop button is a normally-closed (NC) switch wired in series with the power supply output positive rail. When pressed, it opens the circuit and cuts power to all downstream controllers and actuators instantly. The NC configuration means a broken wire or unplugged connector also stops the system — a safety-first design.

Wiring the E-Stop

1. Choose a latching NC mushroom button

Use a standard 22 mm panel-mount E-stop button with latching action and NC contacts. The button should stay latched when pressed and require a deliberate quarter-turn to release.
 

2. Insert in the positive supply line

Connect PSU positive → E-stop NC terminal 1 → E-stop NC terminal 2 → control box / distribution block positive input. The negative rail bypasses the E-stop entirely.
 

3. Label clearly

Mark the button with "EMERGENCY STOP" in red on a yellow background per IEC/NFPA colour coding standards. Mount within easy reach of the operator.
 

4. Test before deployment

While the actuator is in motion, press the E-stop. The actuator must stop immediately and must not restart when the button is released (only after deliberate reset). If the actuator restarts on release, the system has latching control that must also be reset — this is normal and correct.
 
⚠️  E-stop does not hold position An E-stop cuts motor power. An actuator with a self-locking screw drive will hold position when power is removed. However, a backdrivable actuator may drift under load after E-stop. For backdrivable actuators, add a relay-controlled brake or use a self-locking model.

Using a Relay for Isolation

For multi-actuator systems with high total current, wiring the E-stop directly in the supply line may require very heavy-gauge contacts. A better approach: use the E-stop button to control a normally-open (NO) relay coil. The relay's heavy-duty contacts carry the full system current. The E-stop button carries only the relay coil's low current (~100 mA), allowing a standard 10 A rated E-stop button to safely cut a 50 A supply.