Electronic locks work using an electrical current to either lock or unlock the door. Depending on whether the lock is "fail-safe", also known as "power to lock" or "fail-secure", also known as "power to open", supplying the lock with power will either activate or deactivate the mechanism. The terms "safe" and "secure" relate to the status of the door on its secure side (usually the outside). Most electronic door locking devices, whether fail-safe or fail-secure, will have an override option to allow free egress of the building in a power failure event. This ensures that under emergency evacuation, you won't be locked in if the power fails.
Fail-safe or fail-secure locking device?
Fail-Safe (Power to Lock)
A fail-safe lock is one that in its default state is unlocked. Power is applied for it to remain locked under normal circumstances but should the circuit be broken or the power fails, the locking mechanism disengages for the door to unlock and release automatically.
This type of lock is safe for people, which is why we refer to it as "safe" but it will not keep the space secured in a power failure. An additional locking device, electric or mechanical, would typically secure the building once it is empty. When you relate this information to your door being unlocked during a power failure, you may not feel all that safe, but when you think about it in terms of exiting the building with no problem under emergency circumstances, it makes more sense.
Fail-safe locks are usually used for main entry points such as access doors or office doors. Maglocks are the most commonly used fail-safe locking device. They are easy to install, cost-effective and durable.
• It allows large buildings with many visitors (schools, for example) to exit safely and efficiently and emergency responders to enter.
• Ensures the safety of people inside the building in an emergency.
• The building will be unsecured without power if used as the only locking point.
• Leaves the facility vulnerable to crime during an emergency or a false alarm.
• Activating an emergency exit device will disengage the lock.
Fail-Secure (Power to Open)
A fail-secure lock has the exact opposite function of the fail-safe lock, one that in its default state is locked. Power is only applied for it to unlock. Should the circuit be broken or the power fails, the locking mechanism will remain securely locked. Using the electrical current to retract the bolt, it will then remain in the locked position in an electrical outage event. Most fail-secure locks use electric latch retraction technology (EL), which in simple terms means that power is required to unlock the door. The latch will stay in a retracted position whilst power is applied, but as soon as power is removed, the latch projects out to securely lock the door.
This type of lock is secure for the property, but not necessarily safe for people within a building if the power fails during an emergency. Contingency measures should be in place if a fail-secure locking device is used in a building with people usually present, such as a mechanical override key. This, however, is also a way of accessing the door without leaving an electronic trace. For this reason, mechanical override keys are often restricted to those with a higher level of security access.
Fail-secure locks are often used for fire doors that should remain closed to help reduce a fire's spread by sealing off a portion of the space, providing the fire door is not part of an escape route.
• Ensures the building remains secure in the event of a power failure.
• A power failure or EMP (electromagnetic pulse) will not disengage the lock.
• Impedes the entry of emergency responders
• Evacuation can be delayed in the event of an emergency.
How an electric locking device functions will determine whether the loss of electricity will lock or open the door, and not all devices can be found in both fail-secure and fail-safe variants. For example, a maglock, by design can only function as a fail-safe lock. In some circumstances, specific building codes may specify the use of fail-safe or fail-secure electric locking devices.
Some common misconceptions...
Typically, with fail-safe locking devices, backup batteries are installed to avoid unlocking during power outages. This can be counter-productive in some evacuation scenarios, but ensuring an emergency exit device is part of the system, and emergency evacuation procedures are allowed for in any access control software can reduce the risk.
Another misconception is that electric strike/release locks are only fail secure. In reality, electric strikes are available in both configurations, with some capable of both and configurable on-site. What makes electric strikes work are solenoids (magnets) within the strike, shooting a small element back and forth to unlock or lock the strike. The polarity of the solenoid defines if it moves when losing power or stays in position.
Which electric lock is best for you?
The features of a commercial access control or door entry system can differ significantly, depending on the type of business or building they are protecting. For example, there is likely to be a staff room in a retail environment that should not be accessible to the general public. A standalone keypad with a maglock would suffice in this scenario. A larger commercial building with many staff and areas holding sensitive data would require a more substantial system such as a networked access control system with different locking requirements for different rooms.
A secure server room with limited access would want to be secured using a high-security fail-secure locking device, whereas a staff room would be better suited to a fail-safe maglock. Electronic locks offer safety that extends from securing private property to the safety of the general public.
Like all electronics, the options we can explore surrounding electric locking devices satisfy a comprehensive range of requirements. The highest government security properties through to single-occupancy residential properties have all been protected using various electric locks. Even most modern cars have some form of electronic key system.
What are the pitfalls of electric locking technology?
Electric locks are very much a personal adventure to solve specific problems and meet the building and business's needs. As with any other technology, not all electronic locks are the same and will perform different actions. The system you use to open the electronic lock is as important as the lock itself. The final outcome of your protection parings will be shaped by the unlocking and locking devices. It is paramount to consider the personal needs of the end-user as well as the shifting landscape of new technology. A with all technology, electric locking devices, door entry and access control systems are consistently being improved, and new offerings brought to the market.
Typical electric lock types
CMW offer a range of different electric locking options to suit any application. Most electric locks will fall into the following broad categories, although there will always be specialist options out there.
Electromagnetic locks (also known as maglocks)
What is a maglock? How does a maglock work?
Maglocks are most simply explained using theory we learned at school. Magnets have a North and South pole. Magnets repel similar poles and attract opposite poles. Complex aspects of quantum mechanics are represented by magnets being complicated aspects of nature, making that explanation almost too simplified for a beautifully nuanced process.
What makes something a magnet, as most people understand it, is when its atomic domains are structured uniformly in a material. In rare-earth metals, this is accomplished naturally. We can replicate this process artificially using an electrical current which is how a maglock works.
An electromagnet is created when a current is passed either through a wire coiled multiple times around an iron core, or a solenoid (metal core wrapped with a single coiled wire). The metal is no longer magnetised when the electrical current is removed.
The very nature of how an electromagnet is created means it can not be fail-secure. The fail-safe feature of electric unlocking created the founding idea of the electromagnet. The issue maglocks were designed to solve was the threat of doors remaining locked in the event of an emergency with the first maglock made for the Montreal Forum in Quebec Canada as a commissioned safety feature. A door that unlocks automatically with the loss of power was the solution and allowed a series of doors to be opened by actuating a fire alarm.
A maglock generally has two main components; the maglock itself which is powered, and an armature plate that binds to the main body when power is applied.
There are many variations of the maglock of different sizes, varying holding forces, different voltage input options, variations in mounting and additional monitoring options. The most commonly used is the mini maglock, also known as a slim maglock. The small size and reasonable holding force makes it an attractive option for most applications.
As with anything, the correct install will ensure full performance. Many different brackets and housings are available to suit most applications and door types.
Maglocks are disabled typically using a push to exit button that temporarily removes the electrical current before returning the supply after a few seconds, once the door has closed, to activate the lock to bind the door to the door frame magnetically.
Different maglock options
• Standard - up to 1200lb holding force
• Mini maglock - up to 600lb holding force
• Surface mount
• Mortice mount
• Externally rated
• 12 or 24Vdc
• Double door configuration
• Single door configuration
• In the event of an emergency, the lock will open.
• Can be integrated easily into access control or door entry systems
• High holding force available
• Generally easy to install
• Robust and durable
• Require little maintenance
• Can be monitored for the status of the door and the status of the lock itself
• Generally easy to retrofit
• Interrupting the power supply in the building can overcome security.
• Depending on the door and frame gap, the door may be pried open with extreme force.
What is an electric strike? How does an electric strike work?
Electric strike locks, also known as an electric release, come in various options to suit your security requirements. They work using a spring-loaded keeper that secures the latch on the lock in place. Without authorisation for entry, the keeper will stay fastened in place. With proper verification, the keeper loosens and allow the latch to release granting access.
This type of lock can be fail-safe or fail-secure with many offering both options easily configurable by the installer. Building codes for the site and the type of structure may dictate which you are required to install. The device is typically installed within the door frame but is also widely used in double doors by installing the strike within the stationary door (inactive leaf). An electric strike is a great option to allow free egress as the door handle can be adapted to be idle from the outside but still activate the latch from the inside. A key override option is also available in many cases.
Electric door strikes work in various situations with cylindrical locksets, mortise locks, or rim-mounted devices, and their construction allows a mechanical latch to swing out of the way of an opening door.
One consideration that needs to be addressed is the type of door you are installing the electric strike with. This will have some relevance to the faceplate you use, amongst other things. For example, in most cases, a long faceplate would be used in a wooden construct to dissipate any heat generated from the lock with an aluminium door utilising a short faceplate.
There are many options to consider when choosing an electric strike including but not limited to:
• Length of faceplate required
• Surface or mortice mount
• Handing of the door (in some scenarios but not always)
• 12 or 24Vdc
• Fail-safe or fail-secure
• Depth of the door frame
• Monitored or unmonitored
• Adjustable or fixed jaw required?
Electric strikes are generally available in two types, surface mount or mortice (also known as flush mount). When the door has a panic bar, a surface mount option would be necessary, whilst the mortice option would be used with regular door handles. They are available with latch position sensors, which tells the access control system that the door is open and can raise the alarm if programmed to do so.
• Ideal for high traffic areas
• Can be configured on-site
• High security
• Suitable for most door types
• Discreet placement
• More complicated to fit
• Can be very challenging to retrofit
• Require more maintenance
• Higher cost
What is a shear lock? How does a shear lock work?
Shear locks offer an additional level of security to a maglock and work similarly, meaning they can be suitable for almost any type of door install. Shear Magnetic Locks comprise of a magnetic lock with pins that shoot into the aperture plate to give an additional physical locking element. On these types of magnetic locks, the primary method of securing the door is the bolts, meaning it cannot be manipulated using force as a standard maglock can; the power needs to be removed for the pins to release. A vital safety feature is the shear keepers design to quickly retract from the lock bolt in an emergency.
Due to their combined electromagnetic and mechanical locking mechanisms, shear locks are ideal for high-security buildings, as they provide a high physical shear holding force.
It is worth considering the material construct of the door before deciding on a shear lock. Wooden doors have a tendency to expand, contract and potentially warp. This can cause problems with the alignment of the pins in a shear lock. Correct alignment is critical for an operational lock of this type as any small variant can cause the pins to jam and render the door permanently locked until the issue is resolved.
In the event of an emergency, the lock will open
Can be integrated easily into access control or door entry systems
High holding force available
Generally reasonably easy to install
Robust and durable
Can be monitored for the status of the door and the status of the lock itself
Cannot be forced open
Interrupting the power supply in the building can overcome security.
The alignment has a minimal margin for error.
Failure can occur if the door moves/expands/contracts.
Cannot to be used on an emergency escape route
Requires regular maintenance to retain the correct alignment
What is a solenoid bolt? How does a solenoid bolt lock work?
Solenoid bolt locks are a high-security locking option, renowned for their versatility; designed to suit a wide range of door types, including sliding doors, where many other electric lock types are unsuitable and ineffective. It allows you to sustain standards of the highest quality, without compromising security or safety. A solenoid bolt provides a reliable solution for protecting the property.
Solenoid Bolts work by driving a bolt into a strike plate to prevent the door from opening when the lock is actuated by providing or removing an electrical current. Available in fail-safe and fail-secure options, a solenoid bolt is a comparatively simple means of locking a door electronically, with low-level power usage and can easily be fitted into almost any door frame, is designed to suit various applications, guaranteeing a highly secure solution with a high holding force.
• Fail-safe and fail-secure options available
• Can be integrated easily into access control or door entry systems
• High holding force available
• Robust and durable
• High security
• Cannot be forced open
• Discreet design
• The alignment has a minimal margin for error.
• Failure can occur if the door moves/expands/contracts.
• Requires regular maintenance to retain the correct alignment
If you are looking to place an electronic locking device in an external environment, you will need to ensure a suitable ingress protection (or IP) rating. The most commonly used external electric locking devices tend to be maglocks as they can be easily produced as a sealed unit, but there are other options such as some motorised bolts or electric releases.
Electric locking on fire doors will need to be fire-rated in many situations. Many of the options we have discussed above are available with a fire-rating, and sometimes additional intumescent elements may be required.
You can find out about the range of electric locking solutions available from CMW by clicking here. You can also speak to our access control specialist Emma Harris by emailing email@example.com