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Compatibility Issues

What’s wrong with this picture?

When specifying door hardware I understand that it can be like being an kid in a candy store.  But like that kid, you may not be able to always get everything you want.   Sometimes “this” might not go with “that.” There are some examples that should be obvious, such as fire rated exit devices with cylinder dogging, since fire rated exit devices must positively latch each time they close without exception and any kind of dogging could prevent that.  But other combinations of options are less obviously incompatible.

One elusive combination of exit device options that pops up sometimes is delayed egress with electric latch retraction.  In most electric exit devices this is almost a contradiction in terms because they use the same mechanism for delayed egress as they do for electric latch retraction, except it works the opposite way.  For example, the Von Duprin Chexit uses the same kind of motor that the Von Duprin EL devices use, except that the Chexit motor pushes out on the latch mechanism while the EL motor pulls in.  What would be necessary I guess would be to build a little transmission so one could shift gears from push to pull to switch from delayed egress to electric latch retraction and back again.

But since no one has yet invented this miniature transmission neither the Sargent Electroguard nor the Von Duprin Chexit currently offer both delayed egress and electric latch retraction in the same device.  The only device I have encountered so far that does offer these two options together in the same device is Detex.  There could be others.  Check with individual factories to be sure.

Two options that are offered together in many, but not all exit devices, with varying degrees of availability, are cylinder dogging and electric latch retraction.   For example, Sargent offers cylinder dogging with electric latch retraction, but only when factory installed.   Von Duprin offers “Special Dogging” (SD prefix) with electric latch retraction.  In this case the effect of cylinder dogging is accomplished by a cylinder operated latch holdback feature in the center case of the device.  (Not quite the same as traditional cylinder dogging.)  Precision can offer cylinder dogging and electric latch retraction in the same device without complication because their electric latch retraction and cylinder dogging mechanisms happen in different sections of the rail altogether.  Corbin and Yale offer devices with cylinder dogging and electric latch retraction in the same device.   Yes, the electric latch retraction and cylinder dogging combo is all over the charts when it comes to availability.

 





As in all facets of life, when in doubt, contact your friendly door hardware genius.

 

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Experiencing the New Von Duprin Chexit

Chexit door label from Chexit installation instructions.

Von Duprin Chexit door label from Chexit installation instructions.

Last year Von Duprin began shipping Chexit self-contained delayed egress exit devices that are motorized instead of solenoid driven.  Since they are motorized, the new Chexits draw less current and will probably be more reliable than the previous solenoid-driven version. This means a less serious, less expensive power supply, less need for high capacity, high gauge, high cost wire and greatly increased workable wire run distances – all good things.

The new Chexit will do everything the old Chexit did, including release of the outside lever trim when the external inhibit function is activated by access control or another external switch.  That remains a way to get access control out of a Chexit by simply adding a blank escutcheon or other unlocked outside trim to the Chexit exit device.

As of this writing Exit-only function Chexit devices were being shipped less the part number 040193-00 cable used to connect the E996L to the Chexit PC board.  The cables are only provided if you order the Chexit from the factory with trim, but that is okay as long as you want to use no trim or non-electric trim.  Electrified trim is a means to provide fail secure access control from the trim side, so if the fire alarm goes off and powers down the Chexit, the fail secure electrified trim will stay locked.  Entry can still be gained by key.

On another note, recently I was involved in an application where the installer was replacing a mortise exit device and wanted delayed egress from the push side and free ingress from the pull side.  Luckily it was a mortise device, so all I had to do was provide a Chexit mortise exit device with blank escutcheon (passage function) trim because THE MORTISE LOCK ACTS INDEPENDENTLY FROM THE CHEXIT ON THE TRIM SIDE. Cool. 🙂

Bear in mind that  the Chexit remains active while people are using the passage function trim to get in, so if they happen to depress the touch bar, say by bumping it up against the wall for two seconds, they may activate the Chexit alarm.   Von Duprin Tech Support suggested a palm switch on the trim side to activate the inhibit circuit in the Chexit while a person enters from that side.

 





It was fun, easy, and I looked like a … Hardware Genius.

What Is A Pullman Latch?

comparisonA Pullman latch is a type of exit device latch. The leading edge of a Pullman latch, the part that hits the strike first as the door closes, is a ramp.  The back of the latch, the part that rests against the strike to keep the door latched shut, is rounded.  When the Pullman latch comes into contact with another object it retracts automatically.  It is a simple, spring-loaded mechanism.

Some rim exit devices have Pullman latches, but most concealed and surface vertical rod exit devices do not.  Most vertical rod exit devices have a main latch that is shaped like a Pullman latch but also has an additional piece that looks like a kind of separate little latch, or auxiliary deadlatch.  This part interacts with the mechanism of the latch to keep the top latch retracted until this separate piece hits the strike as the door closes.  Then the main latch pops out and locks into the strike.

Latch release extended position.

Latch release extended position.

This latch-and-release design top latch is used by many manufacturers as the mechanism that holds both top and bottom latches in the retracted position while the door is open. That way the latches do not make contact with the surfaces of the door frame, floor or threshold.  When the top latch release makes contact with the strike it releases both top and bottom latches.

The photo to the left shows the latch release fully extended and the latch fully retracted.  This is the state that this type of latch is in when the door is open.

The Pullman latch is most often used with less-bottom-rod (A.K.A. top rod only) vertical rod exit devices when they are to be used with an electric strike.  The normal latch-and-release design is incompatible with most (if not all) electric strikes. Electric strikes that are compatible with Pullman latches are said to have Pullman keepers.

Sometimes Pullman latches are used as the top and bottom latches on vertical rod exit devices because they operate more quietly than standard latches.

Pullman latches are not fire rated and are not for use with fire rated exit devices.

pullmanlatchandkeeper

Illustration of Pullman latch and Pullman keeper. Whereas the locking surfaces of electric strike keepers designed for use with cylindrical or mortise locks is perpendicular to the door frame, the Pullman keeper is at a 45 degree angle to the frame, creating an angled recess to accommodate the unique shape of the Pullman latch.


Quest for the 24-Inch Exit Device with Electric Latch Retraction

Yale7100I had a lot of fun recently trying to meet a customer’s requirement for a 4-foot by 7-foot pair of doors in a hospital that needed to be fire rated and automated.   I found that Corbin and Yale (sister companies whose exit devices are almost identical) offer fire rated surface vertical rod exit devices with electric latch retraction that meet this need.   The installer will be able to put some kind of little power operator on each 24-inch leaf of this four foot pair and cram two fire rated surface vertical rod devices onto these same narrow leaves.  Doubtless it will look odd, but it will work.

Admittedly the whole idea is a bit dubious.  True, by having both leaves opened simultaneously by power operators will provide amply more than the minimum 32-inch clearance demanded by the American Disabilities act, but if anyone manually opens either leaf it certainly will not.

Sargent and Von Duprin offer 24-inch fire rated exit devices, but neither offer them with electric latch retraction.   It is unfortunately necessary to call these companies’ tech support lines in order to verify this information, since their price lists both show 24-inch possibilities without disclaiming the electric latch retraction option.  Neither the Sargent nor the Von Duprin has a note to say the 24-inch device is not available with electric latch retraction that I could see; if that is in fact the case, the buyer is left to beware the exit device order that bounces back because it was ordered with options that are mutually incompatible.

It’s good advice anyway to always call the manufacturer’s tech support whenever there is a question.  Waiting on hold is a lot better than storing thousand-dollar exit devices that didn’t work out on the job.

Note:  A reader named Rick writes in with this about Sargent electric latch retraction:  “Tom, I just stumbled across your site this evening, while doing a search for Fail Secure mag locks of all things (IR says there is one).  But I saw your latest article on latch retraction units and had to clarify the Sargent restrictions. These can be found within the catalog pages, specifically the page showing the 56 option (toward the back). It says:

         MinimumDoorWidths:
              -Wide Stile Door 28″
              – Narrow Stile Door 26″
Thank you, Rick, for this bit of info.  I should add that it is always good to check all the literature at your disposal for any information you are looking for.  Some manufacturers have more detail in their price list than in their catalog, and others vice versa.  Thanks again.


The Double Door Rim Strike – A.K.A. “The Pocket Ripper”

pocketripperOne of the hallmarks of bad hardware choices is the “pocket ripper” strike, used on a pair of doors when there is an inactive leaf with flush bolts or a vertical rod exit device and an active leaf with a rim exit device. Whenever I see this I think, “Cheap bastard,” because the only reason for this half fast solution is money and the desire not to spend it on doing the job right.

This lovely piece of hardware earned the nickname, “pocket ripper,” but hanging into the opening at a convenient height to catch the front pocket of a pair of trousers, resulting in egregious damage to said pocket and colorful language on the part of the victim.

What is the right way to secure a pair of doors? Vertical rod exit devices are the best. My second choice would be a mortise exit device with an open back strike and a vertical rod exit device on the inactive leaf. My third choice would be a mortise exit device with flush bolts on the inactive leaf.

Below are a couple of examples of the ‘pocket ripper.’   On the left is the classic Von Duprin 1609 strike and on the right an example from Ingersoll Rand in Europe.  The European version looks like it has better manners.

In the center we have the Hager 4921 strike that really looks like it could take out more than just a pocket if you catch it the wrong way.

image001image002hager

 

 

 

In addition, I find that often the rim latch stops dead before latching on the strike.  Also, depending on how you install the rim device, the latch may drag across the edge of the other leaf, scraping an ugly divot over time.  Yes, all in all a hardware choice to be avoided if you can.

 

Securitech Trident Multi-Point Deadbolt Exit Lock

Trident 4-point deadlocking exit device.

Simple and robust design helps to ensure security and longevity; single motion egress ensures life safety code compliance.  

Simple to order and to install, the Trident offers excellent security while preserving life safety.

The first thing I noticed when I unpacked the box was the small number of parts.  The second thing I noticed was how well all of these parts are labelled.  As I read the installation instructions I was struck by how easy Securitech had made the installation process, especially with the inclusion of a metal template to help get everything lined up just right.

I assume that the Trident is named for the three active bolts that secure the door on the lock side, but with the inclusion of the passive hinge side bolt it is actually a four point lock.  The hinge side bolt slides passively into its keeper whenever the door is closed.

Trident is a heavy device, so before installing it, make sure your door swings and closes properly and the hinges are in good shape.  I suggest using hinges with non-removeable pins so as not to rely solely upon the Trident’s hinge side bolt.  A stainless steel continuous hinge would be even better for both security and durability, if it is possible to use one.

Every locking mechanism of the Trident is through-bolted through pry-resistant steel plates, so casual attack using a pry bar would likely be fruitless no matter how much time the would-be burglar might have.  Each locking bolt is substantial and housed in a very sturdy mechanism.  Bending one of them would be difficult; bending all of them enough to gain entry would be almost impossible.  The main outside plate is impressive-looking with its Securitech logo and satin stainless steel finish, and since it is through-bolted to the head of the device in several

Photo by Tom Rubenoff

places, it’s pretty strong, too.

The weakest part of any muli-point locking device is the door frame.  Fully grouted (concrete filled) hollow metal frames hold up the best under attack.  At the very least, to have real security measures must be taken to ensure that the door frame cannot be either pulled out of the wall or bent away from the locking bolts.

To maximize security, I suggest not using the optional exterior key control with this device.  The presence of a key cylinder outside provides a target for burglars.

The Trident comes standard with a paddle that tells the user to push to exit and alarm will sound, but since the alarm is optional, this may be an empty threat.  Be sure to order your Trident with an alarm if you want one.

I was impressed with the workmanship evident in how the Trident is put together.  Everything worked super-smoothly and fit together perfectly.  The strong, simple design looks like it will provide many years of flawless service.  I highly recommend it for the back doors of stores, warehouses or factories or anywhere where a higher level of security may be needed.

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.

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.


PS900 Series Schlage Electronics and Von Duprin Power Supplies Demystified

Von Duprin and Schlage Electronics are divisions of Ingersoll Rand. Both are major manufacturers of power supplies for use with electric locking systems and access control. As of January 1st, 2011, Ingersoll Rand discontinued two of their power supply product lines, the PS800 series Von Duprin and the Schlage Electronics 500 series, and merged them into the new PS900 series.

A split in power supply branding may or may not remain, depending on what document you are looking at, but whether they say they are Schlage or Von Duprin, they are all the same PS900 series.

Here is the lineup:

PS902 – 2 Amp output at 12 or 24VDC, field selectable

Compatible with these option boards:

  • 900-BBK: Battery Backup – back up power in case of power outage, includes batteries
  • 900-FA: Fire Alarm – relay for interface with fire alarm panel  – wires to main board
  • 900-2Q: 2 Relay QEL control Board – to run 2 Von Duprin QEL devices
  • 900-4R: 4 Relay Output Board – four relay outputs to operate 4 electric locking devices, not QEL or EL
  • 900-4RL: 4 Relay Logic Board – for man trap or security interlock systems or up to 4 QEL devices
  • 900-8F: Fused 8 Zone Distribution Board – 8 outputs, fused for circuit protection
  • 900-8P: PTC 8 Zone Distribution Board – 8 outputs, circuit breaker protected

PS902 can accommodate 1 of the above option boards in addition to the 900-FA option and battery backup.

For use with electric locks and with Von Duprin Quiet Electric Latch retraction (QEL) exit devices, but NOT with Von Duprin electric latch retraction (EL) exit devices.

PS904 – 4 Amp output at 12 or 24VDC, field selectable

Compatible with these option boards:

  • 900-BBK: Battery Backup – back up power in case of power outage, includes batteries
  • 900-FA: Fire Alarm – relay for interface with fire alarm panel  – wires to main board
  • 900-2Q: 2 Relay QEL control Board – to run 2 Von Duprin QEL devices
  • 900-4R: 4 Relay Output Board – four relay outputs to operate 4 electric locking devices, not QEL or EL
  • 900-4RL: 4 Relay Logic Board – for man trap or security interlock systems
  • 900-8F: Fused 8 Zone Distribution Board – 8 outputs, fused for circuit protection
  • 900-8P: PTC 8 Zone Distribution Board – 8 outputs, circuit breaker protected

PS904 can accommodate up to 2 option boards and battery back up.

Note:  no plug-in for fire alarm relay on main board.  900-FA is only usable with the PS904 if used with an option board.

For use with electric locks and with Von Duprin Quiet Electric Latch retraction (QEL) exit devices, but NOT with Von Duprin electric latch retraction (EL) exit devices.

PS906 – 6 Amp output at 12 or 24VDC, field selectable

Compatible with these option boards:

  • 900-BBK: Battery Backup – back up power in case of power outage, includes batteries
  • 900-FA: Fire Alarm – relay for interface with fire alarm panel  – wires to main board
  • 900-2Q: 2 Relay QEL control Board – to run 2 Von Duprin QEL devices
  • 900-2RS: 2 Relay EL Control Board – to run up to 2 Von Duprin EL devices
  • 900-4R: 4 Relay Output Board – four relay outputs to operate 4 electric locking devices, not QEL or EL
  • 900-4RL: 4 Relay Logic Board – for man trap or security interlock systems
  • 900-8F: Fused 8 Zone Distribution Board – 8 outputs, fused for circuit protection
  • 900-8P: PTC 8 Zone Distribution Board – 8 outputs, circuit breaker protected

PS906 can accommodate up to 3 option boards, fire alarm interface (with option board) and battery back up.

For use with electric locks and with up to 6 Von Duprin Quiet Electric Latch retraction (QEL) exit devices, but NOT with Von Duprin electric latch retraction (EL) exit devices.

PS914 – 4 Amp output at 12 or 24VDC, field selectable

Compatible with these option boards:

  • 900-BBK: Battery Backup – back up power in case of power outage, includes batteries
  • 900-FA: Fire Alarm – relay for interface with fire alarm panel  – wires to main board
  • 900-2Q: 2 Relay QEL control Board – to run 2 Von Duprin QEL devices
  • 900-2RS: 2 Relay EL control Board – to run up to 2 Von Duprin EL devices
  • 900-4R: 4 Relay Output Board – four relay outputs to operate 4 electric locking devices, not QEL or EL
  • 900-4RL: 4 Relay Logic Board – for man trap or security interlock systems
  • 900-8F: Fused 8 Zone Distribution Board – 8 outputs, fused for circuit protection
  • 900-8P: PTC 8 Zone Distribution Board – 8 outputs, circuit breaker protected

PS914 can accommodate 2 of the above option boards, plus fire alarm interface (on one of the boards) and battery back up.

Capable of powering:

  • Up to 4 Electric Latch retraction (EL) exit devices with 900-4RL board
  • Up to 2 EL devices with 900-2RS board
  • Up to 4 Quiet Electric Latch retraction (QEL) exit devices
  • Up to 4 Chexit (CX) delayed egress exit devices off the main board (use 900-8FA combination board if Fire Alarm relay is required)
  • Electric locks or strikes

 

Ordering Tips:

PS-914 is a 4 Amp power supply that is double the capacity of the old PS873, however, from my conversation with IR tech support, their feeling is that it is prudent to power no more than 4 EL devices per PS-914.  Theoretically the power supply could support as many as 8 EL devices however this presents the challenge of timing the relays so that no two can change states at the same time.  If two EL devices are powered up simultaneously the PS-914 could be damaged.

None of the PS900 series power supplies are a drop-in replacement for their predecessors, and the old and new option boards are not cross-compatible with the old and new power supplies.  Therefore, replacing old power supplies with new can present a rewiring challenge.

Ordering back-up batteries can be a little tricky, since they have very similar part numbers for the batteries, the charging circuit board, and a set that includes the board and the batteries.

  • 900-BAT – Pair of batteries only
  • 900-BB – Battery back up board only
  • 900-BBK – Power battery back up kit, board and batteries

 

 

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!

 

 


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