Why do i need to use a diode on the lock connected to a 2n device?

Why do i need to use a diode on the lock connected to a 2n device?

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. 

The diode MUST be installed in the direction shown in the illustrations: Stripe to positive (+). This is the negative (cathode) side of the diode being connected to the positive terminal and this is correct to offer the protection required.

Installing the diode in the reverse direction to that shown 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.

In 2n installations, 1 A / 1000 V (e.g., 1N4007, 1N5407, 1N5408) connected antiparallel to the device is recommended.