Here is detailed information on why the Von Duprin RX-LC Swtich is required by the AD300 and AD400 993 units.  

A low current switch is needed because …

-          The switch must be able to switch micro-amps of current reliably over the life of the device installation

-          Low current switches have gold contacts to guarantee low ON contact resistance

-          Low current switches will not corrode over time and their contact resistance remains low

-          Low Current Switches are normally sealed and are not affected by the environment (humidity, etc)

-          The AD lock requires low current switches to maintain its long battery life in the event that the switch is active for long periods (dogged exit)

-          Higher current switches rely on arcing and contact wiping to maintain low contact resistance.  Low current circuits will not provide arcing to clean the contacts and resistance will build up over time.