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Compact Electric Strikes

A common problem with installing electric strikes is cavity depth – that is, how deeply you need to cut into the frame (or wall) so that the electric strike will fit. For most of the twentieth century electric strikes were, and most still are, designed without consideration for this factor. Instead they are designed for burglary resistance and durability.


Von Duprin 6211 Electric Strike

Click on  the dimensional diagram of the Von Duprin 6211 electric strike at right.   You can see that its total depth is 1-11/16 inches. All of its internal parts are heavy duty, and it has a heavy cast body and a thick, finished face plate. Most of the parts are individually replaceable. To install the 6211 in a hollow metal door frame, the dust box must be removed and often material inside the door frame – sheet rock, wood, masonry, whatever – must be removed in order to accommodate the strike. If the strike must be installed in a grouted door frame the installer is in for perhaps an hour’s worth of work that may involve a masonry drill, a 2-1/2 lb. sledge hammer, a masonry chisel and safety goggles.

HES 5000 Dimensional DrawingsIn more recent years a new generation of low profile (shallow depth) electric strikes has become available, offering unprecedented ease of installation. The HES 5000 (illustration at left) was one of the first strikes on the scene to offer a depth of only 1-1/16 inches, and advertised that it could be installed without even removing the dust box from the frame. I have found it is usually much easier to knock out the dust box for wiring reasons, but it is true that the unit will fit neatly inside most original equipment dust boxes in hollow metal frames.

More recent offerings in the shallow depth electric strike department include the Trine 3478, the HES 8000 and the Adams Rite 7440, illustrations shown at the end of this article.  All are UL Listed burglary resistant. The HES 8000 offers 1500 lbs. holding force, the 3478 offers 1200 lbs. holding force and the Adams Rite, with its innovative double keeper design, offers 2400 lbs. of holding force.  The Trine 3478 offers an install with a very tiny lip cutout, and the HES 8000 offers the advantage of needing no lip cutout at all. Each of them fit in a strike cavity only 1-1/16 inches deep.

These strikes have revolutionized electric strike installation. Before, a good installer might install six or ten electric strikes in a day. Now a really fast installer might be able to install 20 or more, greatly reducing labor and other costs associated with installation.

What’s the Trade-Off?

None of the internal parts of these strikes are available. When these strikes break, you throw them away and buy new ones. Also they do not last as long. Whereas it is not unusual to see a Von Duprin 6211 or a Folger Adam 712 still in use after 10 or even 20 years, 6 years of service is a long time for a low profile strike. In ten years you might be replacing a spring or solenoid in a Von Duprin, but you might be installing your second or third low profile strike in the same door frame in that same amount of time. This is a small inconvenience.

Upon installing that third strike in the same hole, you probably will not yet have equaled the price of a single Folger Adam 712 or Von Duprin 6211. If price up front is the primary consideration, low profile is definitely the way to go. But if in about 12 years you are installing the fourth replacement strike in the same prep, those expensive, harder-to-install, heavy duty strikes start to look like a much better value.


HES model 8000, Trine model 3478 and Adams Rite model 7440

Thank you.

Schlage CO and AD Series Mortise Lock Parts

Schlage AD Series

Schlage AD Series

This just goes to show that there is no substitute for field experience. In the quest to provide the best service to his customer, this locksmith went past my advice and the advice of factory tech support to find the best solution.

The locksmith inquired about a replacement latch for a Schlage CO200MS mortise lock. I called Schlage Tech Support and they said that there were no replacement parts available for that CO-200 Series mortise lock chassis; that the entire mortise chassis had to be replaced for a hefty sum and I relayed this info to the locksmith. The locksmith, however, knew that Schlage advertised that the CO series locksets incorporated the Schlage standard L-series lock chassis “for durability and dependability.” Based on this, the locsksmith took a chance, went to the parts list for the L-Series mortise lock with the same function and ordered the replacement latch. He reports that is identical and works fine.

Good to know! One can assume that many parts from the L Series mortise lock with the same function will work in all AD and CO series mortise lock bodies. Like I said, you learn something new every day.

Thanks for stopping by.

Securitron’s new PowerJump ICPT™ Inductive Coupling Power Transfer

Securitron’s new PowerJump ICPT™

Securitron’s new PowerJump ICPT™

The door hardware industry breathlessly awaits the debut of Securitron’s new PowerJump ICPT™ Inductive Coupling Power Transfer.  The PowerJump is Securitron’s miraculous new device that may put a significant dent in the electric through-wire hinge market.  I mean, why would you drill a half inch hole the width of a 36-inch door when you could install this little pair of black boxes on the lock side?

I downloaded the installation instructions from the Securitron web site to check out product attributes and characteristics.  The first thing I noticed, having spent much of my career working with wooden doors, that the Securitron PowerJump ICPT is a bit friendlier to a hollow metal door or frame install than it is to a wood door or frame install.  Because the body of the unit is almost the same size as the face, the installer must take great care to cut a very clean hole for the body so that the hole does not exceed the size of the face.  This can be a little tricky when using a speed bore bit (or auger bit as mentioned in the instructions) to drill the two deep holes for the mortise pocket before cutting in the face.

One trick I have used to use when installing mortise locks was to cut in the face first and get that nice and clean before drilling the holes.  I had good success with this because it gave me a very clear outline to stay within – much like coloring inside the lines with crayons in kindergarten.  Installing the PowerJump is a lot like installing a really small mortise lock, actually.  The face is the same width and a standard architectural grade mortise lock – 1-1/4 inches.

The PowerJump ICPT draws 500mA at 24 volts DC on the frame side, will transmit it across up to 3/16 inch of empty air and output either 250mA at 24VDC or 500mA at 12VDC on the door side.  500mA seems a little slim to be powering an electrified mortise lock.  Usually I like to see a bit of a cushion when it comes to current, so I would usually not power a device that requires 250mA at 24 volts DC, like a Sargent electrified mortise lock, with a power source that provided no more than the 250mA required.  I’d be a lot happier with a power source that has a capacity at least 1.5 times as great as the appliance being powered.

However, the average electrified hinge with 28-gauge through-wires only has a current rating of about 160mA and we have been powering electric mortise locks with these for decades.  Since I am not an electrical engineer I am not sure how that works, but it does.  I am also mystified by the science behind transmission of electrical current by induction.  Therefore, like most installers, I trust Securitron to produce yet another innovative product that works well.   I’ll be waiting to hear how installers like it when it is finally released.  I know I’ll hear about it one way or another.

Securitech Lexi Electrified Exit Device Trim

Great Problem Solver

The Securitech Lexi series retrofit exit device trim is available with a variety of back plates and adapters that allow it to be used with most major brands, including many surface vertical rod and concealed vertical rod exit devices.  Compatibility with a variety of vertical rod devices is a major plus.

I mean, anybody can electrify a rim exit device by simply installing an electric strike.  However, while it is possible to install an electric strike on a vertical rod device it rarely brings a good result.  First of all, in order to use an electric strike you have to first lose the bottom rod.  That just leaves one latch at the top of the door to provide all the security.  If it is a tall door or a flexible door – like an aluminum storefront door – you can pull the bottom open several inches with just that top latch holding it.  Add a little time and a little hinge sag and pretty soon you have no security at all.

The other solution is electric latch retraction, or electric latch pullback, as some manufacturers call it:  relatively expensive compared with a Lexi trim.  Also, electric latch retraction is a fail secure only solution when locking trim is used and therefore may be inapplicable to fail safe installs such as stairwells, unless passage function (always unlocked) trims are used.

I notice that right out of the box the Lexi is very self contained.  Other than a tiny box containing mounting screws, tailpiece operators, and a cylinder collar and cam, what you see is pretty much what you get.  It’s pretty hefty for its size – it is designed on the slim side so as to be usable on narrow stile as well as hollow metal or wood doors.   This does mean that the installer may have to be a little creative when replacing a larger exit device trim with the Lexi.

Installation instructions are easy to follow and short – only four pages, including the template. Something I would have liked to see in the instructions, but didn’t, was current draw.  If I am installing one of these, the number of amps it draws are not going to matter much to me.  But if I am installing twenty of them and want a centralized power source, now it’s an issue.  Yet it isn’t anything that an experienced low voltage specialist with a ammeter can’t find out in two seconds.

One of the great innovations I noticed right away is the rotation restriction clip that allows the installer to customize tailpiece rotation to the exit device.  I do not think that this is handled better by any other manufacturer.  Correct degree of rotation often determines whether a trim will work or not, and to have a trim that has degree of rotation so easily selectable is damn nice.

As mentioned in the sales literature, since Securitech’s Lexi trim is compatible with so many exit devices, if you have a facility with different brands of exit devices dispersed throughout, you can install access control and unify the exterior appearance at the same time.  And in addition to being versatile it is also durable.  Forcing the lever only causes its internal clutch to break away, and it can easily be set right by rotating it back the other way.

All in all the Securitech Lexi trim seems to be a well built, versatile problem solver.  I think you’ll find it useful in many access control installations.

Cabinet Access Control

Rutherford Controls 3510 Electric Cabinet Lock

Cabinet security was already a concern in hospitals where drug theft is a problem, but has become an increased concern particularly in U.S. hospitals where new HIPAA privacy security regulations have mandated that patient data be secured by key or pass code locking device.  There are a wide variety of locking arrangements available to accomplish the task.

Simplex combination cabinet locks appear often in this application.  They are relatively inexpensive, not too hard to install, and accomplish basic compliance with HIPAA.  The regulations state that access to codes (or keys) should be limited, however, when you have a five-button mechanical combination lock, several hundred people can know the combination in a very short time by word of mouth.  Therefore a more costly and complex solution might be necessary in order to comply with the spirit of the regulations that are designed to actually protect patients’ privacy.

The best way to control people is to make them individually responsible.  That’s what electronic access control is all about.  Typically an institution adopts electronic access control for the audit trail capabilities that monitor who does what, where and when.  So if a patient’s information goes viral on the ‘Net, the debacle can more probably be traced back to its source.

As for credentials, biometrics is the most secure since one cannot share their fingerprint, but card or fob credentials are also effective.  People are less likely to share any credential that can be traced back to them.  Of course, unlike a fingerprint on a live finger, a card or prox fob could be stolen.   I do recommend a physical credential of some kind because PIN numbers are too easily shared.

The drawback to electronic security as applied to cabinets is that most available, good access control hardware tends to be hard wired.  Wiring can be difficult in such tight spaces, yet there are some solutions available.  For example, a resourceful access control installer could use an SDC model 1583 electromagnetic cabinet lock and an IEI Prox.pad keypad/proximity reader to secure a cabinet.  For a fail secure locking device, an RCI 3513 electric cabinet lock could be substituted for the SDC 1583.  The system would run on 24 volts DC and would need a power supply, but at least you could get audit trail and time zone capability out of it, with a Wiegand output for your existing access control system.

There are some glimmers of hope.  There are some stand-alone, battery operated cabinet locks that read a proximity card or i-Button.  But these are simply add-and-delete-user systems that allow control of who has access but does not keep track of when.  Without audit trail capability, access control is little better than that Simplex mechanical combination lock or a regular cabinet lock with its regular brass key.

For now the ultimate solution for cabinet security seems to be to put the cabinet in a locked room and use access control on the room rather than the cabinet.  But I think that will change, don’t you?

Hot Stuff: Continuous Duty Electric Locking Devices

The Ohm Symbol

I regularly hear complaints about electric strikes, cylindrical locks or mortise locks that are hot to the touch.   When I ask, I am always answered that, yes, the device is being used in a continuous duty application.

Continuous duty means that the electric lock or strike is powered continuously, usually for several hours a day.  Most fail safe locks and strikes are run continuously, since they are usually locked part of the day and they require electric power to lock.  Whenever a door is kept unlocked by using an electrical timer, the lock or strike that is controlled by the time is run continuously for part of the timing cycle.

Heat in an electric lock or strike is caused by resistance in the electrical circuit as it passes through the coil of the solenoid inside the device.  Often this heat is sufficient to “burn out” the solenoid.   The solenoid does not actually catch fire, usually.  The term, “burned out” refers to a solenoid that has been ruined by excessive heat so that it no longer functions.

Heat from electrical resistance is exacerbated when there are problems with the supply of power.  For example, if the power supply provides less than sufficient amperage to constantly power the solenoid, the solenoid will ‘run’ hotter.  Similarly if there is a current drop because of a long wire run with inadequate wire gauge, the solenoid will not get sufficient current and will run hot.  Also if the voltage supplied is significantly higher than the solenoid is rated to accept, that could create a heat problem as well.

Often, however, there is no detectable reason for the solenoid to run hot.  Sometimes, it seems, they just do.

A great way to mitigate the problem of the hot lock or strike (when all power supply problems have been solved) is to use an electrical device in line with the electric lock or strike that provides it with a full inrush voltage and current upon activation and then reduces the voltage and/or current to a holding level, allowing the solenoid to run cooler.

Several companies offer these units.  Here are some examples:

  • HES:  Model 2005M3 Smart Pack controller
  • COMMAND ACCESS:  CRU-2 current reduction unit
  • TRINE:  LC-100 line conditioner



Multi-function Doorways, Part One

As seen in Doors and Hardware Magazine.

Whenever something is invented, humans find more uses for it.  This is certainly true for door automation and electric locking.  It was not long after people realized a door could be unlocked remotely using an electric strike and a door could be opened automatically using a power operator (automatic door opener) that they began using these devices together.   Of course this combination of devices was soon interfaced with intercoms.  Exit devices with electric latch retraction and electromagnetic locks were thrown into the mix, as well as access control, delayed egress and/or security interlock systems.  Any of these systems alone is sufficient to complicate an installation, but when you start to use several on one opening, that’s when things really start to get interesting.

A hospital can be one of the best places to run into a doorway that needs to perform many functions (pun intended).  Hospitals seem to have more varied reasons to keep different people out at different times, or to let them in or out by different means.  In addition to standard life safety and security issues, hospitals also have to anticipate the needs of patients who may be under the influence of medication and/or mental disorders and/or have physical limitations.  Some patients must be kept inside for their own safety while all patients must be able to exit swiftly and safely in the event of a fire.

Let’s use as an example a hospital emergency ward entrance used primarily by ambulance drivers.  The hospital wants only ambulance personnel and the security guard  to be able to activate the power operator, and to control access by use of a remote switch operated by the security guard  for the general public and an access code by hospital employees (other than ambulance personnel).

Since it is a pair of doors, concealed vertical rod exit devices are the most efficient, safe and secure way to lock them and provide reliable free egress in the event of an emergency.  However, since there is a power operator involved, these devices must be equipped with electric latch retraction; and since use of the power operator was to be limited, a second electric means of opening the door would be required.

A simple way to solve the problem of the second means of unlocking is by using electrified exit device lever trim with one of the concealed vertical rod exit devices.  Persons not requiring the power operator can get in by using the access control, or the security guard  can “buzz” them in using one of two remote buttons.  Because there will be two means of unlocking the door electrically, the security guard  will need a small desk unit with two buttons:  one that activates the power operator and electric latch retraction and one that activates the electric exit device trim.

Below is an amateur wiring diagram (made by me) of how, basically, the system works.

Central to the concept is an access control device with two relays and a request to exit input.  This allows several of the connections to be made through the access control system.  If the access control system on site does not provide more than one relay, the same functions can be accomplished by using additional relays in the power supply.

The system as shown in my illustration above works like this:

Ambulance personnel activate the power operator using the access control system.  The access control system signals the power operator via contact closure in Relay #1.  The power operator triggers the relay in the power supply to retract the latches of the exit devices, then opens the door.

Other authorized hospital personnel use the access control system to unlock the lever trim.  The access control system changes the state of Relay #2, triggering the relay in the power supply to unlock the trim.  They turn the lever, pull the door open and walk in.

Injured people arrive on foot at the Emergency Room entrance.  The Security Guard sees them (or is notified by intercom, not shown) and lets them in by pressing the red button, activating the power operator, or by pressing the green button that unlocks the exit device trim.

There exist many possible variations of this system.  Knowledge of access control systems and door hardware are required, but the most important principal in play is the use of contact closure to signal multiple devices.

The Elusive “Touch Chip” Credential

A few years ago, Ingersoll Rand (IR) purchased Locknetics Security Engineering in Connecticut, and since then gradually rebranded the line as Schlage Electronics.   A little over a year ago, as part of the process of closing the Connecticut facility, Schlage Electronics started phasing out its TR80 and TR81 touch readers.  These readers were based on the old technology of the Dallas chip, otherwise known IR/Locknetics land as the touch chip or iButton.  By the end of 2010, Schlage phased out all commercial electronic locking products that incorporated touch chip readers, such as touch readers and locking technologies that incorporated the touch reader, such as the CM line of computer managed locks and their electromagnetic locks with on-board access control.

When the new price books were released in January 2011, the touch chip credential was completely absent.   When questioned about legacy systems, representatives from IR indicated that touch chip users should migrate over to prox tags.  With the new AD and CO series electronic locks, Schlage made available new software and a new hand held programmer (the HHD-KIT) that is backwards compatible with the old hardware.  They also produced a tag with a prox chip on one side and a touch chip on the other so that legacy facilities would be able to carry both credentials over the period of years during which the old CM or other series locks would age out of the system.

One might think that the touch chip has completely faded from the Schlage Electronics scene, but such is not the case.  Looking through the Multi-Family Price Book what do I discover but the new SRT-100 touch reader and a barrage of “iButton” touch chip credentials such as the one pictured.   The new CT-5000 controller that replaces the old CT-1000 controller is also available for those who need to replace ailing legacy systems.  It is my understanding that the iButtons that appear under the multi-family division are fully compatible with legacy technologies such as CM locks or KC-2 series locks.

There is also a new line of smart residential locks that incorporate touch chip technology.  So it is safe to say that touch chip technology is not going to disappear anytime soon.  So if you have a large facility full of old Locknetics products that take iButtons, don’t panic.  At least for now you can still get them.


Understanding Door Security Monitor Switches

A number of different kinds of switches are available to help you keep track of whether or not your door is shut and / or locked.  Here are some of them:

Door Status Monitor Switch

A door status monitor switch changes states when the door is opened or closed.  Typically this is accomplished by using a magnetic reed switch, either surface mounted or concealed in the edge of the door and door frame like the one shown at right.

How a Magnetic Reed Switch Works

The magnetic reed switch is typically installed on the door frame and the magnet that activates the switch is typically installed on the door.   Inside the magnetic reed switch, a thin piece of steel – a steel ‘reed’, if you will – is held in position by the attraction of the magnet when the door is closed.  When the door is opened, the magnet is taken away from the switch and the spring tension of the “reed” causes it to spring back against the other contact, changing the state of the switch.

Most magnetic reed switches are normally closed – “closed loop” – but are also available normally open (“open loop”) SPDT (single pole double throw, or “form C”) or DPDT (double pole double throw).

The Purpose of the Door Status Monitor Switch

The door status monitor switch is used to notify remote devices that a door is open or closed.  Typically these remote devices are burglar alarm panels or access control system controllers.   It does not tell you if the door is locked, just if it is closed.

Request to Exit Switch

The request to exit switch, also known as a REX switch, is so named because it is usually connected to the request to exit contacts on an alarm panel or access control board.  It is used to notify an external device that someone is exiting through, or wants to exit through, a door.  REX switches come in a wide variety of configurations, from push button palm switches engraved “push to exit” to switches concealed inside exit devices.  A motion exit sensor is also a form of request to exit switch.

Request to exit switches are available with a wide variety of contact configurations and with or without electronic or pneumatic time delay.   If the switch is being used as a means of egress for pedestrian traffic, it will need to comply with life safety code.  Life safety code varies from locality to locality as governed by your local AHJ – Authority Having Jurisdiction – that is, your local building inspector or fire marshal.

Latch Bolt Monitor Switch / Strike Monitor Switch

I write about Latch Bolt Monitor (LBM) switches and Strike Monitor Switches because they somewhat overlap.  Both are designed to monitor the position of the latch bolt.

Some LBM switches are inside locks and others are in electric strikes.  From inside the lock, they monitor whether the latch is extended or depressed.  When located in an electric strike, they monitor whether or not there is a latch bolt present in the keeper.

Pictured at right is Securitron’s line of inexpensive strike monitor switches as examples of strike monitor switches.  Several companies offer like products.  Strike monitor switches are an easy way to monitor if there is a latchbolt (or some other object) present in the keeper.   Several companies, such as Von Duprin, offer heavier duty monitor strikes.  Monitor strikes are sold as a finished unit that includes as strike and a switch whereas strike monitor switches are aftermarket add-on units.

Magnetic Bond Sensor / Bond Sensor

Magnetic bond sensor and bond sensor options refer to electromagnetic lock applications.  Many manufacturers offer Bond Sensor or Magnetic Bond Sensor as an option.  What this does is allow an electromagnetic lock to notify some external device that its holding force is below spec.  Authorities are alerted and the situation is addressed.

Maximizing Effectiveness

To maximize effectiveness of door monitor switches, it is best to use both a door status monitor and some kind of lock status monitor as well, and this is why:  because monitor switches can be fooled.  A door status switch will tell you if the door is open or closed – unless it has been altered to tell you the door is closed when it is not.  Also, a door may be closed, but not locked.  If you have a latch bolt monitor or magnetic bond sensor in place as well as a door status switch, you will know if the door is closed but not locked.

This is the center of this knowledge:  to know that the door is shut AND locked.




Low Voltage Detective Work


Finding the Current Drop


As electric locking systems become increasingly complicated, troubleshooting these systems has also become more complex.  Yet certain basic principles always apply.

Case in point, a customer had access control on a stairwell door using a fire rated mortise exit device with an electrified mortise lock.  The solenoid in the mortise lock had burned out twice and the third one, newly installed, was already too hot to touch.  Granted, a solenoid operated fail safe device used in a continuous duty application will get warm, but it should not get too hot to touch.  So they called me to help them figure out what was going on.

To find the problem, I first listed the possibilities:

  1. They had gotten three defective solenoids in a row
  2. The power supplied is the wrong voltage – if the voltage was either too high or low, that would cause the solenoid to heat up
  3. The current supplied is inadequate – the solenoid used 330mA.  If it were being supplied with only 150mA, for example, the solenoid would heat up.

We determined that 27 volts DC was available at the door to power the 24 volts DC solenoid – perfectly acceptable – and we all felt that it was rather unlikely that they had received three defective solenoids in a row.  So that left current drop.  Where was the current going?  What was preventing it from getting the current it needed?

The access control tech on site could not determine whether the solenoid was getting enough current at the door by using a meter (for whatever reason) so we traced the current back through the line.

The power supply was a 6 amp, 24 volts DC power supply that had an output board with 8 fused outputs.  If all were in use, then a max of 750mA should be available from each output, provided they all were carrying the same amperage load.  We determined that four of the outputs were being used:  three were used to power electric strikes at 300mA and one was used to power the electric mortise exit device at 330mA.  The sum of the current draw for all devices attached to the power supply was therefore about 1.2 amps – well within the power supply’s capacity.  Therefore the power supply size was not the problem.  The technician measured the output from the contacts that were connected to the mortise lock and found that they were outputting correct voltage and current.  Therefore the output board was not the problem.

Assured by the technician that the wire run between the power supply and the mortise lock was less than 100 feet and that 18 gauge wire was used, I knew that the wire run was not the problem.  I asked how power got from the door frame through the door and into the mortise lock.  The technician responded that power transfer was accomplished by use on an electric hinge.

Typical wire gauge in an electric hinge is 24 gauge – a thin wire to be sure, but since power only needs travel a few inches through it, hinge wire gauge is usually not a problem.  But this electric hinge had its own 3-foot wire lead threaded through a raceway in the door to the mortise lock.  Whereas a few inches of 24 gauge wire might not be a problem, I reasoned, three feet of it might be a problem.  We talked about it briefly and then agreed that they would give it a try.

To my dismay, they called back two hours later – after they had replaced the wire running through the door with 18 gauge wire and let the mortise lock run on it for a while – and let me know that this did not work either.

The answer finally came when I asked how the electric mortise lock was connected to access control and was told there was a controller in a box above the door.  The controller used a form C relay to turn the electric mortise lock on and off.  I suggested that the technicians check the relay to make sure it was working properly.  When they did they discovered that the electric mortise lock had been connected in series with another device.  This other device – whatever it was – drew enough current to deprive the mortise lock of the current it needed to operate without burning up.  Problem solved.

The moral of the story is that, yes, access control has only gotten more complex as time goes by, but by using simple, logical methods a good technician and figure out and repair most problems.  So stick with it and keep asking questions until you ask the right one.


And good luck!