Electromagnetic locks only require the contact of a metal plate, usually at the top of the door, with a plate whose magnetic field is created by electricity to secure the door to its rated force, which is expressed in pounds. Those door plates can be small, highly polished and stylish, if required.

• High security – “Anything with a lock is vulnerable to picking, but there is nothing to pick with magnetic locks,” points out David Engebretson, SDM’s contributing technology writer and president of Slayton Solutions Ltd., Chicago.

• Fail-safe – “It is what we call a high-security lock with high holding force, yet it is truly fail-safe,” points out John Schum, vice president of sales for DynaLock Corp., Bristol, Conn. “It helps with life safety rules. There’s no mechanics involved or mechanical mechanisms that can bind up or stick or jam.”

  Adds Bryan Sanderford, national sales manager for Dortronics Systems Inc., Sag Harbor, N.Y., “If they are without power, magnetic locks will unlock to allow emergency egress from a building without any mechanical action required. In cases where you need a higher level of security, simply providing a battery backup to the system allows for continued access control in times of power failure.”

• Low maintenance – “It’s really hard to damage it and it’s extremely reliable,” insists Schum regarding electromagnetic locks. Sanderford agrees. “They do not wear out,” he maintains. Flush contact is maintained continuously by pushing the plate against the magnet.

  “The striker plate actually floats around the pivot on the door so there is approximately one-quarter inch of movement there,” explains Richard Sedivy, director of marketing for DoorKing Inc., Inglewood, Calif. This allows it to compensate for the difference between the door angle and the magnetic lock surface. “It’s a good flush contact for maximum holding force,” he emphasizes.

• Easy installation – “It is easier to mount than any other lock,” Schum points out. Sanderford declares, “The mag lock by its nature is surface-mounted and requires no special fitting into the door frame.”

• Aesthetics – “Aesthetics frequently are a major consideration for the owner and the architect/ designer,” Sanderford points out. “One advantage of magnetic locks is that they can be used with all glass-style doors, since they’re mounted on the frame rather than the door itself and do not require mechanical latching mechanisms in the door.”

Use of electromagnetic locks is suggested in facilities that have high traffic and life safety issues, notes Rich Hagala, customer support manager for Securitron Magnalock Corp., Sparks, Nev. “That could be auditoriums, shopping malls, department stores, airports or railroad stations, anyplace where you’re looking for a high-durability, low-maintenance device that will give you a lifetime of trouble-free usage.”

Why Electromagnetic?

• an electromagnetic (mag) lock,

• an electric strike, or

• some other electromechanically operated mechanism, such as an electric lockset.

Manufacturers’ list prices for common electric strikes are $100 to $200, notes Rick Geringer, vice president of marketing for SDC, Westlake Village, Calif. Strikes with higher security range from $300 to $400, he maintains, about the same as a medium- to high-security electromagnetic lock that could hold from 1,200 pounds to 1,600 pounds.

Geringer prices electrified mortise locksets in the range of $500 to $600. Sometimes they cost more than the doors on which they are installed, he points out, but sometimes they are chosen by architects for aesthetics and for places mag locks cannot be used. Electrified locksets are fail-safe and fail-secure.

“Electromagnetic locks are more expensive than an electric strike, but there are other considerations,” Sedivy declares. “They use less power than an electric strike. There’s no mechanical moving parts – you can’t destroy them. They’ll last forever, and that’s where the cost savings come in over the life of the lock. They’re really a better buy in the long term.”

Sanderford also considers more than product price. “The key factor here is your installation cost,” he insists. “On a retrofit, the mag lock installation is generally considered less expensive, including the cost of the unit, than an electric strike.

“What I find is that dealers who install the locking hardware themselves prefer to use mag locks,” Sanderford maintains. “Dealers who subcontract that work out to a locksmith, they really don’t care. A lot of locksmiths specialize in the installation of that type of product, like a strike, and they have the tools and equipment to install strikes and locksets, so for them it’s not as difficult as it would be for a security dealer who didn’t have personnel with the same training.

“On a new application where the door and frame can be prepared by the manufacturer to accept a certain brand and model of strike, then the field cost for installation of the device is less, although there you must really consider the cost of the door and frame that the manufacturer added,” he notes.

Another strike against strikes is that their coils can burn out from being turned on and off each time the door is opened, whereas the coil is on constantly with an electromagnetic lock except when it is opened, Sedivy points out. “Turning it on and leaving it on is better than turning it on and off,” he maintains.

Only as Strong as the Door

He also thinks mag locks are good for interior doors where access is controlled. These can have backup power for security in the event of a power failure, which is not allowed by most codes on exterior doors to allow emergency exit.

Sanderford explains, “What the locks do is provide a means of limiting who can get in and when, and tracking through an audit trail those that with their I.D. gained access.”

Another factor to consider is the holding force in pounds required, which ranges from approximately 500 to 2,000 pounds. Obviously, an electromagnetic lock only needs to be rated for the strength of the door it holds.

“Even on a glass door, I’ve seen an electromagnetic lock rated for 650 pounds of holding force because who would throw their body at a glass door?” asks Schum rhetorically. “In 25 years in the industry, I’ve never heard of a 1,200-pound lock violated by a human being. People go to 1,500 pounds for the highest security more for peace of mind. The difference between 1,200 and 1,500 pounds is salesmanship.”

Sanderford agrees, recommending approximately 500 to 1,000 pounds holding force for interior doors and a holding force of 1,000 or more for higher security, such as exterior doors or interior computer room doors.

“An approximate rule of thumb is that a 180-pound man can exert 850 pounds of impact force with his shoulder,” Sanderford estimates. “Therefore, you don’t have a lot of security if you don’t have at least 1,000 pounds of holding force unless the door will disintegrate anyway. The door and frame need to be substantial to be able to utilize the locking force that’s available.”

Sanderford recommends for higher security a heavy solid wood door or a hollow steel one that should be reinforced depending on its use.

Mag locks usually are installed above a door. “The best position for a magnetic lock is the header,” Geringer recommends. In this application, the lock plate is attached at the top of the flat side of the door that swings shut and makes contact with the magnetic plate attached to the door jamb.

“If a door closer does not leave enough room for lock installation to the header, it may be installed at the top of the side jamb,” Geringer advises. “However, this may not comply with other building code criteria that require a minimum unobstructed opening width.”

Schum adds, “For detention areas, so you can’t pull open the door and pass contraband through, we mount two mag locks vertically along the latch-bolt side of the jamb at the top and bottom.”

Sanderford has observed this use in casino money counting rooms, psychiatric wards, high-security government rooms and merchandise distribution facilities.

Hagala recommends for exterior use a midrange metal hollow frame door with a 1,200-pound mag lock. For interior applications where the door is for “keeping honest people honest,” he recommends a 600-pound lock.

For high security applications, military complexes or even detention centers, a 1,800-pound lock would be appropriate. “With a 600-pound lock, a good linebacker could get the door to pop open,” Hagala maintains. “At 1,200 pounds, now you would need to back a mid-size vehicle up to it and the bumper would give out. At 1,800 pounds, any standard entry trims or poles come off before you move the lock.”

During the 1992 riots in Los Angeles, aluminum glass frame doors that were broken out still had two-thirds of their frames left dangling by their 1,200-pound mag locks, which had not given out, Hagala recalls. “In a lot of cases, such as hollow wood doors, 1,200- or 1,500-pound mag locks generally are overkill at that point,” he concedes.

Installation Ease

Schum adds, “A strike is less expensive, but it is not a lock – it is only as good as the latching device on the door.” He points out that electromagnetic locks sometimes have strikes also for extra security.

“Electrified hinges are required if you use electrified locksets, but not mag locks, because the electrical mechanism is in the door, so your power thru the lockset must pass from the lock side of the door over to the hinge side of the door and then to the frame to get back to the power source and control,” Schum explains.

For fail-safe performance with high security, aesthetic appeal, low maintenance and easy installation, electromagnetic locks can be an elegant solution to security needs.

Sidebar: Buy the Book – See the Lock

Sidebar: Achieving Egress

• switch on request-to-exit bar,
• passive infrared (PIR) motion detector,
• button on wall, and
• manual pull station on wall.

Although the appearance of an egress bar resembles a mechanical “crash” bar, it actually is a switch that cuts power to the electromagnetic lock.

“Rather than require people to push an exit switch, it’s better to use a request-to-exit bar,” recommends Rick Geringer, vice president of marketing for SDC, Westlake Village, Calif. “If someone is in a panic, they shouldn’t need prior knowledge on how to exit. Especially in an emergency, they’re not going to be thinking to look for a switch.”

Automatic egress on the interior of a building can be provided by PIR motion detectors, which react to changes in infrared energy. Microwave motion detectors, such as those used in retail stores, are significantly more expensive, points out Rich Hagala, customer support manager for Securitron Magnalock Corp., Sparks, Nev.

“We don’t recommend PIR on a glass atrium door on the south side of a building because of heat changes during the day,” advises John Schum, vice president of sales for DynaLock Corp., Bristol, Conn.

Buttons on the wall are used when automatic egress is not desired but no access code or I.D. card is needed. Local codes vary, but on interior doors in many jurisdictions, exit switches are acceptable.

“But in other cities, if you do use a switch, you have to add a motion detector to it,” Geringer of SDC points out. “Then the exit switch is there only if the motion detector doesn’t work.”

Adds Bryan Sanderford, national sales manager for Dortronics Systems Inc., Sag Harbor, N.Y., “A wall-mounted pull station is being used more and more in that all codes require that the locks be wired to the fire system, so in case of a fire they will release. The average person doesn’t realize if they pull the fire alarm, it will unlock the doors.

“Therefore, a clearly marked emergency-door-release pull station can advise these people of the ability to unlock this door and this door only,” he points out. “It will simultaneously send the signal to security of a security breach and provide a local alarm at that door.

“Where we really see it used a lot is where access is being used for both ingress and egress from the facility and there is no crash bar or push button on the door,” he explains. “Personnel are required to use their I.D. card to leave the facility, so in an emergency they may not have their card with them.”

Delayed egress also can be provided. “Most American manufacturers of mag locks have a delayed egress magnetic lock system,” Schum adds. “It’s a smart lock with a built-in microprocessor that can be programmed.”

These are popular in installations where egress must be provided according to codes but security is important. The delay is thought to deter thieves in retail, commercial and industrial facilities, prevent unauthorized access in airports, and even stop patients with dementia from exiting doors in long-term health-care facilities.

A sign usually is required by code on a delayed egress door that says, “Emergency exit only. Push until alarm sounds. Door can be opened in 15 seconds.” Some jurisdictions also allow 30-second delays, Schum maintains.

“It’s a compromise between the life safety and security people, who are both trying to do their jobs at the same time,” concedes Hagala.

Schum notes that an audible or visual alarm indicates that the door is working and also can deter thieves and alert health care professionals to an unauthorized exit.

“The more seamless the integration into the building system is, the more comfortable the user and the security and life safety people are going to be with it,” Hagala points out.