Locknetics 740 Series Break Glass

Locknetics models 740, 741 and 742 all operate by the same basic function. A glass lens covers a push button which is depressed behing the glass. When the glass breaks, the button is free to pop out which activates the unit.

These models are designed to be used in areas with emergency doors. The doors only unlock in case of emergency.

A typical installation would be a laboratory outfitted with an emergency exit door. The door is not to be used on a regular basis and remains in the locked mode. In an emergency, a person would break the glass lens with the hammer releasing the push button. The released push button would unlock the door allowing exiting through the door.

A common wiring configuration involves both a break glass unit and a power supply.

One wire runs from the power supply to the break glass supplying constant power to the unit. This way it is always powered up and ready to go. A second wire runs back to the power supply and is connected to one of it's input terminals. Upon activation, this second wire sends a signal to the power supply to unlock the door.

Larger buildings have fire alarm systems and it is common to wire the unit to that system as well. A third wire can run from the unit directly to the fire alarm. Upon activation, both the power supply and fire alarm would receive signals to go into action.

Another option is to connect the power supply and fire alarm together. When the power supply recives the signal from the break glass, it first unlocks the door then signals the fire alarm system to sound.

Check with the provider of the fire alarm as to which wiring version works best for them.