Ask the Experts | Ask the Electronic Access Ace


I have been asked to install electric strikes for a security integrator. They are installing access control in the building and they are asking me to install protection diodes. I’ve never done this before can you tell me more about them?



A protection diode is one of a few suppression devices for electronic door hardware. It is a standard semiconductor device integral to the safe and proper function of the access control system, it acts as a grounding tool, allowing the flow of current in one direction only. When a door strike is activated, the coil sends a spike (also called “kickback voltage”) down the line. Without a diode, the kickback voltage would damage the control panel over time. When properly installed, the diode keeps kickback voltage localized at the lock.

It’s important to protect your access control equipment against this electrical kickback. To do so, the diode MUST be installed across the powered lock (at the strike) between positive (+) and ground (-).

The diode MUST be installed as close to the lock as possible. The best scenario (where possible) is to splice the diode in parallel (shown in image below), connecting it to the positive (+) and negative (-) strike wires using a wire connector of your choice. (I prefer to use dolphin connectors and heat shrink tubing.)

Installing the diode backward for a strike can cause issues with your door controller. A damaged or blown (dead) diode can act as if there is no diode at all. When troubleshooting your access system always check to see if a protection device is installed.

The diode MUST be installed in the direction shown in the illustrations: Stripe to positive (+), black to negative or ground (-).


Installation of Diodes

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