ELECTRIC STRIKE LOCKS AND MAGNETIC LOCKS

 ELECTRIC STRIKE LOCKS AND MAGNETIC LOCKS

Access control locks on doors have come a long way in the past 30 years or so. They contribute more than you might think to our safety and security while at work, or while spending time in public buildings such as schools, government buildings, and healthcare facilities.

There’s a lot more than meets the eye when it comes to electronic door locking hardware. Because of their importance to safety and security, we thought we’d spend some time exploring two of the most common types of access control locks in use on buildings today — electric strike locks and magnetic locks — and discuss their different features, benefits, and potential drawbacks.

If you own or manage any kind of commercial building, healthcare facility or school, this post will give you a better understanding of these two very popular locks, including some of the advantages and disadvantages of each.

 

You’ll often see the terms “fail-safe” and “fail-secure” when looking at different access control systems. These are important terms to understand because they tell you how the lock will function in the event of a power failure:

·        “Fail-Safe” requires power to lock the door. If power is lost, then the door will become unlocked. (Typically Mag Locks)

·        “Fail-Secure” requires power to unlock the door. If power is lost, then the door will remain locked. (Typically Door Strikes)

It’s also important to have a basic understanding of the different parts and how they function together. Most door locks have three major components that work together to keep the door secure. They include the handle and the latch (the small metal bolt that sticks out of the side of the door when open), which together make up the lockset, and the strike. The strike, or “strike plate” is the metal plate or assembly installed on the inside of the door frame and is aligned to receive the latch and hold it secure.

Electric strikes are electromechanical door locking devices, meaning they are mechanical locks with electronic devices that provide additional functionality.

Electric strikes are used in combination with another form of locking devices, such as a lock set or a panic bar. They are installed in place of the conventional lock strike plate on the inside of the door frame. Electrical power is supplied to the strike, which holds the latch or lock bolt in place, keeping the door locked until the release system is activated.

The type of release system chosen will vary based on the application. Examples of release systems for electric strikes include reception release buttons, a keypad for entering passcodes, electronic key card or fob readers, etc. Once the release system is activated, a hinged piece of metal inside the electric strike will pivot to allow the door to open without having to turn the door handle.

The lock or panic hardware functions independently of the electric strike. Therefore, while the electric strike plate functions to keep the door locked from the outside, even if the power is out, you can still open the door from the inside by turning the door handle or pushing the touchpad of the panic hardware. This is an example of a fail-safe function. However, depending on the application, most electric strikes can be set to either fail-safe or fail-secure using an integral switch.

Magnetic or “Mag” Locks

Mag locks are electromagnetic door locking devices. A mag lock consists of a large electromagnet installed along the top of a door frame and a metal plate on the door that lines up with it. The lock functions by passing an electric current through the electromagnet, creating a magnetic charge that attracts the plate and holds it in place against the door frame. This keeps the door securely locked until the power is removed or interrupted.

Examples of release systems for mag locks include many of the same devices as for electric strikes. When energized, a mag lock can create a retention force greater than 1,000 pounds, making it a very effective lock. That is, until the power is cut. Because mag locks by design require a constant supply of electricity to remain locked, mag locks are fail-safe only — they do not function to keep the door locked from either side when the power is out.

Choosing the Right Locks for Your Building

When comparing magnetic locks to electric strikes, important factors to consider include whether it will be used on an interior, exterior, or fire rated door; the purpose of the door; and the relevant life safety regulations.

Budget concerns, while also important, should be considered secondary to these. Choosing a lock based solely on cost often leads to higher costs in the end when it is discovered that the lock is not code-compliant or that it does not work for the application for which it was intended.

The following table provides a summary of some of the features of each type of lock and some of the advantages and disadvantages that you may want to consider when choosing a locking mechanism for your doors.

Features	Electric Strikes	Mag Locks
Functionality	Electromechanical	Electromagnetic
	Works in combination with a mechanical locking mechanism by replacing the standard fixed strike of the lock with an electronically controlled strike.	Works independently of the mechanical door latch by means of an electric current passed through an electromagnet installed on the door frame creating a magnetic charge that bonds to a metal armature plate on the door.
	An access control device is used to trigger the strike plate and release the lock bolt or latch.	An access control device is used to cut power to the electromagnet to trigger the release of the lock.
Power Fail Modes	Can be fail-safe or fail-secure.	Only available fail-safe.
Installation	Mounted in the frame, and its wires are typically inside the frame.	Installed on the face of the door and frame, it can be installed relatively easily by most contractors.
Advantages	An electric strike is much less likely to delay egress because it can be easily operated from the inside of the building.	One of the most effective types of hardware for securing both sides of a door.
	Lockset can stay locked but the strike releases to allow the power operator to freely swing the door open.	Easy to install with no interconnecting parts.
	Acts as a release — Can be used on a door with an automatic opener.	Reliability — with no moving parts, they suffer less damage in an attempted forced entry.
	Availability as either fail-safe or fail-secure allows for a wider variety of uses.	Quick release — unlock instantly when the power is cut, allowing for quick release compared to other locks.
Disadvantages	Visible to the door user, which can make it more susceptible to tampering	Potential safety hazard — can slow egress in the event of an emergency.
	Complexity of devices typically requires skilled installers	Can fail in the event of a power outage, disabling security.
	Must be precisely matched to the hardware on the door, or they will not work	Can become difficult to open the longer the mag lock is continuously locked.
		Requires battery backups to be secure during a power outage, which requires routine inspection and replacement of batteries.
		Can be easily tampered with.
Relative Costs	$$-$$$	$$$-$$$$

It is important to remember that door locks in public buildings must meet applicable regulations based on the type of door on which the lock is to be used. Most safety codes pertain to egress doors — those that provide occupants a way to escape the building in the event of an emergency. This includes a number of different types of interior doors and exterior doors.

In most cases, door hardware is required to provide for free egress at all times with hardware that is readily openable from the egress side without a key, special knowledge or effort; and depending on the code, may also require the ability to open in one action. Relevant regulations regarding means of egress can be found in:

·        Chapter 10 of the International Building Code (IBC) and International Fire Code (IFC)

·        Chapter 7 of the National Fire Protection Association (NFPA) 101 Life Safety Code

·        Chapter 11 of the NFPA 5000 Building Construction and Safety Code

Additional regulations regarding the use of locks on fire rated doors can be found in Chapter 6 of the NFPA 80 Standard for Fire Doors and Other Opening Protectives.

You may need one or both types of locks on the different doors within your building. Hopefully, this post has provided you with the information you can use to determine if the locks you currently use for access control are adequately meeting those needs and are compliant with all the relevant codes. If you’re not sure, SSA Integrate can help. We have Certified Access Control & fire experts that can help you determine the best solution to meet your security needs while keeping you compliant with all the relevant codes. Contact SSA Integrate today to learn more.

Elevator Surveillance Guide

 Elevator Surveillance Guide

Installing surveillance in an elevator can be challenging. Small but wide areas, vandal resistance, and transmission methods all present challenges not found in other areas cameras are installed. In this note, we look at:

• Form factor: Box vs. dome vs. specialty
• Resolution: How much is necessary?
• Transmission: Wired vs. wireless vs laser methods
• Dealing with electrical contractors

Form Factor

The first decision to make when considering elevator cameras is form factor. Minidome and corner mount are the two most common options in use as they most compact compared to box, bullet, or full sized dome cameras. Other form factors, such as box or bullet may be more easily tampered with due to the low ceiling height of the elevators, and more easily knocked out of position.

Minidome

The key advantage to minidomes is camera choice, as most manufacturers offer cameras in this form factor, with numerous resolution and lens options. These options are not generally seen in corner mount cameras.

However, they are more obtrusive than many corner mount housings, and do not blend into the interior of the elevator as well. Where aesthetics are the key concern, domes may not be preferred.

Corner Mount

This type of mount places the camera in a roughly triangular housing made to cover one of the elevator's corners. Some are sold as unitized housing/camera packages, while other manufacturers sell housings meant to accept a box camera. Size and appearance varies depending on manufacturer:

They key drawback to corner mount cameras is limited availability. Most manufacturers do not offer corner mount options, and those that do typically only offer one or two models, with limited resolution and lens choices. Larger corner housings built for box cameras add more flexibility, but are larger and more obtrusive.

Field of View/Resolution

Given elevators' small size, generally under 10' wide, users typically choose to cover the full car instead of just the doors. This gives them not only the opportunity to view comings and goings, tracking subjects throughout a facitity, but to view potential incidents in the elevator, as well. However, care should be taken that pixels per foot (PPF) does not drop below acceptable levels for recognition if no other cameras will provide facial shots of subjects, e.g. lobby and hallway cameras.

For example, using an actual 103° field of view from an elevator camera with Camera Calculator, we can see the difference between VGA, 720p, and 1080p in a typical 8x8' elevator. Estimating ~9' to target to reliably capture subjects as they enter through the elevator doors, 720p provides 56 PPF in this scene. This is likely enough to provide identification quality video under good lighting. VGA provides only 28 PPF, too low for recognition, while 1080p provides 85, more than enough.

Mounting Height

Since most people look down while walking, and criminals may actively avoid cameras, mounting height in elevators should be carefully considered for the best chance of capture. As we found cameras are typically best mounted as low as possible, with ~8' being a "sweet spot", better able to see those with heads down or hats on while also see over subjects beneath the camera.

This image shows the effects of mounting height and the subject's face angle, displaying the difference in capture quality at various mounting heights with the subject's face level as well as tilted down.

Signal Transmission

Once the camera has been selected, installers must decide how signal will be carried from the elevator. There are three typical options for this:

• Traveler cable
• RF wireless
• Optical laser

Traveler Cable

Connections between the elevator car and the machine room for power and signal are made via a specialized traveler cable. This cable is attached to the car, typically to the bottom, and to the top or center of the shaft. The construction of this cable varies, but it typically contains multiple twisted pair conductors for power and control, and possibly a UTP or coaxial cable for video. 

This image shows cross-sections of various flat traveler cables:

Generally speaking, since these cables are often attached to the top of the shaft, making the cable approximately twice the height of the shaft, UTP is not a usable solution for Ethernet. Buildings of 12-14 stories can easily have a 300' traveling cable, which exceeds the maximum distance category cables can be run, before even considering horizontal runs to an equipment room or IDF. In low-rise buildings, UTP may be an option, however. Fiber-optic and coaxial cables may be considered otherwise.

RF Wireless

The second option is to opt for wireless connectivity, utilizing a pair of wireless APs between the car and bottom or top of shaft. Both are used in practice, with the bottom of the shaft generally chosen for easier servicing. In this case, local power must be obtained from the car, which may involve the elevator contractor. Power is readily available, however, due to lights and air conditioning installed in the car.

Wireless eliminates the issue of necessary conductors in the traveler cable, but presents challenges of its own. Cables and conduits located in the elevator shaft may cause interference, making wireless connectivity unreliable. Very narrow beamwidth antennas may be used to compensate for this, but antenna alignment must be carefully set and maintained over time.

Optical Wireless

Optical wireless uses a pair of laser transceivers, one mounted to the car, the other in the shaft, to send/receive data. This is specified to handle elevator shafts up to 75 floors.

Optical product performance is degraded by dust, dirt, and other debris which may fall in the elevator shaft and as such should be cleaned regularly.

Dealing With Elevator Contractors

Normally, most facilities maintain service contracts with an elevator contractor, since the elevator must undergo routine maintenance. These contractors may be difficult to deal with, as a number of users have shared. They are often hesitant to modify existing traveling cables for new services, simply because it complicates (however slightly) their routine maintenance of the elevator with a system outside their control. If the traveling cable is insufficient to add video, installing a new cable is, most times, cost prohibitive, and may remove the elevator from service for several days. Both of these add up to expenses users may not wish to incur.

To avoid the coordination and expense required to have the elevator vendor add video to a car, users and integrators may attempt to add their own cable to the car. There are two things to be aware of in this case: 

• Third parties attempting to modify the cable without the contractor's permission will void warranties and service contracts in most cases. Even leaving existing cables alone and simply zip-tying a new UTP cable to it may be frowned upon.
• According to NEC code, hoistway cables must be listed for use in these applications, and be of type E. Standard UTP, fiber, and coaxial cables do not meet these requirements.