Fail-Safe = power to lock (Mag locks can only be fail safe) Meaning: from the key-side of the door if the power is off you will NOT NEED a key to get in. Fail-Secure = power to unlock. (Exit Devices with Latch Retraction can only be fail secure) Meaning: from the key-side of the door if the power is off you will need a key to get in If you need to chose between Safe or Secure then Lever-locks, Electric Strikes & Exit-Trims can be Safe or Secure. How to choose which one, Exterior doors should be fail secure. Stairwell Doors or locked EXIT doors should be fail safe. How Fail-Safe works: If the Building Fire Alarm goes ON (some people say OFF) then all the power to the locks will be shut off and ALL the Fail Safe locks are now unlock (free egress both ways in or out) No one will get TRAPED in the fire. How Fail-Secure works: If the Building Fire Alarm goes ON then all the Fail Secure locks will remain locked you will need a key (free egress from the non-key side only) People can get TRAPED in the fire. You might see this in the part #'s FSE = (Fail-Secure), EL = (Electronically locked) FS = (Fail Safe), EU = (Electronically Unlocked) LR = (Latch Retraction) for exit devices Exit Device & Trims Notes: Its best/preferred to always use Electrified Trims on a Exit Devices, and not Latch Retraction. Why Less Amps to move the smaller solenoid and its quiet and it can be Fail Safe or Fail Secured. Latch Retraction With large solenoid (not motors) require lots of Amps and the solenoid is large & loud. Solenoid are fast and loud, Motors are slower and quieter. And Latch Retraction can only be Fail Secure never Fail Safe.
