Don't let a $50 surge destroy a $50,000 safety system.
But there is a silent assassin that destroys all that hard work:
Bridging the Gap: Why your PL (Performance Level) doesn't matter if your SPD (Surge Protection) fails.
Here is the hard truth: A lightning strike 100 meters away, or switching a heavy inductive load inside your plant, can generate a 6kV surge. That surge doesn't care about your safety rating. It will weld contacts, fry logic, and degrade sensitive semiconductors in your safety relays and PLCs.
We spend a lot of time calculating Performance Levels (PLr) for safety circuits under ISO 13849-1. We verify the Category, MTTFd, and DCavg religiously.