Last week I got a compliment about this site from a security consultant, and I asked him if there were any topics he’d like me to do a post about. He said that a post on electrified lever trim (E) vs. electric latch retraction (EL) would be helpful since he spends a lot of time explaining the difference to his clients. So Michael, this is for you, and everyone out there who has been wondering how to choose between the two.
Both of these terms refer to electrified panic hardware functions. The products look essentially the same after they’re installed, but provide two distinctly different functions:
- How it Works: Electricity controls the locking/unlocking of the lever handle, so the lever can be used to retract the latch.
- Function: Can be fail safe (electricity locks the lever) or fail secure (electricity unlocks the lever). The panic hardware provides free egress from the push side at all times.
- Applications: Used for stairwell reentry, or for access control when the latch doesn’t need to be retracted electronically.
- Advantages: No special power supply required, low current draw. Can interface with fire alarm to provide “fail safe” door operation – door unlocked but still latched upon fire alarm. Very quiet electronic operation.
- Disadvantages: Can not be used for doors with automatic operators or where latch needs to be retracted electronically. Increased mechanical usage of the panic hardware because the latch can’t be held retracted (dogged) and the latch engages in strike each time the door is closed.
EL (Electric Latch Retraction)
- How it Works: Electricity retracts the latchbolt(s) of the panic hardware, so the door can be pushed or pulled open without retracting the latches manually.
- Function: Fail secure only – when power is cut, the latches project and secure the opening from the pull side. The panic hardware provides free egress from the push side at all times.
- Applications: Used for access control – especially high volume openings where doors will be left unlocked for extended periods, quiet operation of doors to sound-sensitive areas, dogging of fire doors such as cross-corridor pairs (fire alarm projects latch), and doors with automatic operators (latch must be released before door is opened by auto operator).
- Advantages: Latch is held retracted electronically, reducing the mechanical usage of the panic hardware and eliminating the sound of the latch engaging in the strike. With electric latch retraction panic hardware, door pulls can be used instead of lever handles where aesthetics are top priority. Provides “dogging” function for fire doors.
- Disadvantages: High current inrush for some models requires specific power supply located in the vicinity of the door, and larger gauge wires. Electric retraction of latch is audible on some models (although Von Duprin now offers the QEL – Q for “Quiet). Can not be used for stairwell reentry or locations where “fail safe” operation is required.
Feel free to chime in with anything I forgot to mention. If there are other topics or questions you’d like me to cover, please let me know!