When it comes to building safety and access control, emergency break glass units, often referred to as emergency door release (EDR) devices, play a crucial role. These green call points allow people to manually unlock electronically secured doors in an emergency.
What Is an Emergency Break Glass Unit?
An emergency break glass unit (or EDR) is a safety device typically installed next to electronically locked doors/gates. In the event of a non-fire emergency, such as an access control failure, pressing or breaking the unit immediately releases the lock, allowing for safe passage without triggering the fire alarm system.
The green colour of these call points is intentional:
- Green = Safe action permitted.
- It clearly distinguishes them from fire alarm call points, which are red, and helps users quickly identify the right device during an emergency.
Understanding Break Glass Unit Colours
Different colours represent different emergency functions. Here are the five most common break glass units you may come across and their meaning.
Types of Emergency Break Glass Units
Depending on the application and environment, there are several types of break glass units available.
1. Internal Break Glass Units:
Typically installed inside buildings, these are positioned adjacent to access control doors to ensure quick manual release in case of an emergency.
Features:
- Surface mounted or flush fitted
- Available with an audible sound and an illuminated front cover
- Single, double and triple pole options available
2. External Break Glass Units:
Designed for outdoor use, these EDR units are IP rated to protect against weather conditions such as rain and dust. They’re often installed next to access-controlled gates.
- IP67 rated (surface mounted)
- Resettable unit
- Single, double and triple pole options available
3. Combined Dual Unit
The break glass offers a manual override that cuts power to the lock in an emergency, ensuring safe evacuation. With the added benefit of having either an exit button or key switch above it.
Benefits
- Convenience: Provides both normal and emergency exit options in one location
- Cost saving: Reduced installation time and less components to fit
- Resettable unit
4. Resettable Break Glass Units
A resettable unit uses a mechanism that allows the device to be reset after activation, without replacing the glass.
Benefits:
- Reusable and cost-effective
- Simplifies maintenance
- Ideal for access control environments where frequent use or testing is required
5. Traditional (Non-Resettable) Break Glass Units
The classic break glass design includes a glass panel covering a button or lever. To activate, the user breaks the glass permanently triggering the release.
Features:
- Requires glass replacement after activation
- Ensures clear, one-time emergency use
- Suitable for environments where misuse must be discouraged
6. Single, Double, and Triple Pole Units
Break glass units can also differ in their pole configuration, depending on how many circuits they control:
- Single pole: Controls one circuit
- Double pole: Operates two circuits (e.g. door release and alarm signal)
- Triple pole: Provides more complex control for integrated systems
Why Break Glass Units Are Essential for Access Control
Break glass units ensure that safety and security work hand in hand. While electronic access control provides protection and management of movement, manual override points guarantee that people can always exit safely during emergencies or system malfunctions.
When choosing a break glass unit, consider:
- The environment (internal or external use)
- Whether you need a resettable or non-resettable design
- The level of integration required with other safety systems
Find The Right Emergency Door Release For Your System
Selecting the right emergency door release is essential for ensuring both safety compliance and user confidence in any access-controlled environment. Whether you require an internal resettable unit or a weatherproof external model, installing the appropriate break glass call point can make a critical difference in an emergency.
Our stocked range of green emergency door release units includes internal and external models, dual units with touch free or press to exit buttons, and reset keys.
Need help selecting the right solution? Our team is here to guide you, so contact us today.
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