access control – Page 4 – Door Hardware Genius

Exit Devices with Electric Latch Retraction

Overview

Almost all exit device manufacturers offer the option of electric latch retraction on their touch-bar style exit devices. Different manufactures may call it by other names such as ‘latch pull-back’ or ‘remote dogging’. Some people refer a device with electric latch retraction as an ‘electrified exit device’, but that could also refer to electric unlocking of outside trim – a different animal altogether. Electric latch retraction is accomplished by using a solenoid or electric motor to actually retract the latch or latches of an exit device.

Below are some characteristics of electric latch retraction:

Electric latch retraction is fail secure. When power is supplied, the latches retract. When power is shut off, the latches extend, securing the door.
Electric latch retraction works well with power operators because when the latches are retracted, the doors can swing free.
With electric latch retraction, pairs of doors can continue to be latched top and bottom.

Cheaper alternatives, such as using an electromagnetic lock or an electric strike, would result in double doors that are only locked at the top. If they happen to be aluminum narrow stile doors locked only at the top, a person could actually pull the bottom of the locked door open several inches with very little effort. Such installations are at best sloppy, at worst not secure.

Solenoid vs. Motorized Latch Retraction

Solenoid driven electric latch retraction usually requires a specialized power supply due to the high inrush of current required (between 12 Amps and 16 Amps at 12 or 24 Volts DC). Motorized latch retraction generally requires just over 1 Amp of current for activation.

Solenoids are generally louder than motors, since solenoids move abruptly whereas motors retract at a slightly slower pace, and are therefore quieter.

Global Considerations

Check door width. Electric latch retraction devices may not fit if the door is too narrow.
A means of getting current from the door frame into the device, such as a door cord or electric power transfer will be needed.
Voltage drop due to length of wire run could be an issue with high current inrush devices.

Following are examples of electric latch retraction exit devices by different manufacturers.

Please keep in mind that any of the part numbers shown may change without notice at any time.

Adams Rite

Adams Rite makes hardware primarily for aluminum-and-glass storefront type doors, but also for standard hollow metal and wood doors. All of their exit devices are available with MLR (motorized latch retraction) or solenoid latch retraction (EL for rim devices and LR for all other devices). They make rim, concealed vertical rod, surface vertical rod, and mortise exit devices.

MLR motorized option draws 850 mA during retraction and 370 mA when maintained in dogged hold position at 24 VDC. Available in 24 VDC only. (ex. part number 8xxxMLR)
EL solenoid driven option (for rim devices, example part number 8801EL-36-12) draws 1.5 Amps at 12 VDC and 600 mA at 24 VDC
LR solenoid driven option (example part number 8xxxLR-36) draws 16 Amps at 24 VDC (inrush) and 500 mA (holding current) at 24 VDC

They do not offer a retrofit kit for field conversion of existing devices as of this writing, but aftermarket kits are available from other manufacturers.

Falcon / Doromatic

Falcon makes Doromatic exit devices primarily for aluminum storefront doors. All of their touch-bar style devices are available with electric latch retraction. Currently they use the Von Duprin-type solenoid for latch retraction, and use the Von Duprin PS914-2RS power supply to handle the 16-amp inrush current these solenoids draw.

The PS914-2RS will power up to 2 exit devices with electric latch retraction.

Doromatic offers a solenoid driven electric latch retraction field retrofit kit for their 1490 series concealed vertical rod and 1590 series rim devices as well as factory installed electric latch retraction. The EL1690 concealed vertical rod device and EL1790 rim device can be used field retrofit kits to electrify the 1990 and 2090 series crossbar “pipe-type” exit devices for latch retraction since they have the same latch side footprint and the vertical rod devices can use the existing rods.

Falcon offers their grade 1 series 24 and 25 exit devices with electric latch retraction or motorized latch retraction and field conversion kits.

Falcon exit device example part numbers:

EL solenoid latch retraction (EL25-R-EO 3 US32D)
MEL motorized latch retraction (MEL25-R-EO 3 US32D)

Example field conversion kits:

ELK-3 or ELK-4 (or 650147 or 650148) solenoid latch retraction kit for 3- or 4-foot 24 or 25 series exit devices. Specify finish.
25-MELK-3 or 25-MELK-4 (or 47266630 or 47266631) motorized latch retraction kit for 3- or 4-foot 25 series devices only. 24 series MEL devices are factory only. Specify finish.

Precision

Precision makes exit devices for hollow metal, aluminum storefront, and wood doors, fire rated and non fire rated. All of their touch bar-style exit devices are available with electric latch retraction, and they offer both solenoid driven and motorized electric latch retraction for their grade 1 devices.

ELR solenoid latch retraction (ex. part number ELR2103 630 36)
MLR motorized latch retraction (ex. part number MLR2103 630 36)

Precision makes retrofit solenoid electric latch retraction kits specific to various device characteristics.

Non-fire rated 3- or 4-foot wide stile exit device: ELRK-3 / ELRK-4
Fire rated 3- or 4- foot wide stile exit device: ELRKF-3 / ELRKF-4
Non-fire rated 3- or 4- foot narrow stile exit device: NELRK-3 / NELRK-4
Fire rated 3- or 4-foot narrow stile exit device: NELRKF-3 / NELRKF-4

They make one kit to convert any of their touch bar devices to motorized latch retraction:

RPMLR-K

Sargent

Sargent offers a wide variety of exit devices in various functions and configurations to accommodate diverse applications. All 80-series models are available with “Remote Dogging / Latch Retraction”. Sargent recommends the Securitron BPS-24-1 power supply, a simple 1-amp, 24VDC power supply, to power electric latch retraction devices.

To designate Remote Dogging / Latch Retraction they use a prefix 56- to the exit device part number.

Example part number: 56-8810F 32D

Sargent offers two kinds of retrofit kits to convert existing Sargent exit devices to motorized latch retraction in the field. The R56A kit includes a complete touch bar (specify finish) whereas the M56A consists of a motor and control module unit that is unfinished. Rail size (according to door width) must be specified for either. Sargent uses letter designations for rail size:

E = 24 to 32 inch door width
F = 33 to 36 inch door width
J = 37 to 42 inch door width
G = 43 to 48 inch door width

Example part numbers:

Modular kit: M56AF
Push Rail Assembly Kit: R56AF 32D

Von Duprin

Von Duprin offers two kinds of electric latch retraction in rim, surface vertical rod, concealed vertical rod, mortise, and three-point exit devices for narrow stile aluminum storefront, standard hollow metal, and wood door applications. To order exit devices with latch retraction use prefix EL for solenoid latch retraction or QEL for motorized latch retraction.

EL prefix devices require the PS914-2RS power supply. PS902-2RS are the manufacturer’s recommendations for QEL prefix devices, but any regulated and filtered power supply 2 Amps or greater will do. If powering 2 devices simultaneously, the PS902-2RS will stagger the inrush, firing one QEL at a time. Since each draws 1 Amp, simultaneous activation of two devices might max out a standard 2 Amp power supply. If another manufacturer’s power supply will be used to power two devices, I suggest using a 3 Amp power supply.

Wire run/current drop factors apply.

Example part numbers:

Solenoid latch retraction: EL99EO 3 26D
Motorized latch retraction: QEL99EO 3 26D

Von Duprin offers a variety of retrofit kits to field convert existing exit devices to electric latch retraction. Options include motorized latch retraction kits, kits that include rail backplate (specify door 3 or 4 foot door width), kits with motorized latch retraction and hex key dogging, etc. Here I list part numbers for the most common variations:

Solenoid Latch retraction (EL) kits:
- For 3-foot door width: 050070
- For 4-foot door width: 050078
Motorized latch retraction (QEL) kits:
- For 3-foot door width: 958003
- For 4-foot door width: 040065

Dorma

Dorma offers solenoid and motorized latch retraction for their 9000 series exit devices. ES is the designation for solenoid driven latch retraction and MLR for motorized latch retraction. They offer full replacement touch bar and rail assemblies that can be used to field convert devices to ES or MLR.

Example exit device with latch retraction part numbers:

With solenoid latch retraction: 9x00B RHR 630 ES
With motorized latch retraction: 9×00 RHR 630 MLR

ES option requires Dorma PS501 power supply.

MLR option, Dorma DKPS-2A power supply recommended, but any 2 Amp regulated and filtered power supply will work.

Rail size designations:

A – for door width 34 inches to 48 inches
B – for door width 28 inches to 36 inches
C – for door width 25 inches to 30 inches

Touch bar and rail assemblies, example part numbers:

MLR option motorized latch retraction: MLRTBR 630 B
MLR option fire rated motorized latch retraction: MLRFTBR 630 B
ES option solenoid latch retraction: ESTBR 630 B
ES option fire rated solenoid latch retraction: ESFTBR 630 B

Wiring Through a Door

AKA coring the door or drilling a raceway.

Like Moses leading the Hebrews across the Red Sea, you must work a miracle to bring electricity from the hinge side of the door to the lock side. Luckily it is a miracle on a much smaller scale. Moses had to deal with millions of gallons of water and miles of sea bottom whereas you only have to deal with a few feet of wood. So relax.

Raceway Reasons

The best way to get a wire raceway into a door is to order the door with it already built in. This is especially true of hollow metal doors which often have cross members inside at angles to where the through-wire needs to go. However, that would require planning in advance – a rare occurrence these days, it seems. Lack of planning is the main reason that field-drilling a raceway becomes a necessity.

Coring the door is usually the best option whenever you are installing an electric lockset. This is true whether you use a door cord or an electric hinge. The safest place for the wire is inside the door.

You will probably also need to drill a raceway if you are using an electric strike in the inactive leaf of a pair of doors. Usually you will also need a door cord, electric hinge or other power transfer.

Horizontal vs. Vertical

It is possible to drill a raceway with the door still up. I have done it but I don’t recommend it. It takes nerves of steel and a stiff, sharp drill bit. You need a decent sized bit that won’t bend right or left on you as you try to drill straight, and you need to make sure that the door doesn’t move on its hinges while you are drilling.

I found that taking the door down and standing it on edge in a homemade door stand is the easiest for me because:

The door is much less likely to move while you are drilling it
Using a level to guide you is much easier, and
Gravity is on your side

Constants

Certain constants apply to either horizontal or vertical drilling. In both cases I recommend a 3/8-inch by 3-foot drill bit. If the door is more than 3 feet wide, drill it from both sides or get a 4-foot bit. I prefer to drill from both sides because it’s a lot easier to drill straight for 18 or 24 inches than it is to drill straight for 3 or 4 feet.

If you have a drill with a built-in level, use it. If your drill does not have a built-in level, any level will do. Just put it against the door anytime you want to check the angle at which you are drilling. Determine if the door has a beveled edge and don’t let the bevel skew your path through the door. Make sure your drill bit remains parallel to both the interior and exterior surfaces of the door.

Drilling a raceway across a door is a challenge, but all it really takes is good focus and an ability to drill a straight hole. If you are challenged in the latter aspect, you might consider a drilling tool like the Security Door Controls product shown below. If you have many raceways to drill, a tool like this one is a great idea.

Security Door Controls 7000IDF Door Drilling Kit

Fail Safe and Fail Secure Electric Locking Devices

Definition

Basically:

Fail Safe = power off, it’s unlocked
Fail Secure = power off, it’s locked

Electric locking devices include:

Electric strikes
Electromagnetic locks
Electromechanical locks
Electrified exit devices

Most electric strikes are sold fail secure by default. For example,
if you order a Von Duprin 6123 24V US32D, and architectural grade 1
electric strike, it will most likely come fail secure regardless if
it has Von Duprin’s “FSE” (standing for fail secure) in the part number
or not. The part number in the Von Duprin price book does not include
“FSE.” To be sure you are going to get a fail safe electric strike (not
the norm) if that is indeed what you want, in this instance you would
include Von Duprin’s abbreviation for fail safe, “FS”, for example,
6123 -24V-FS-US32D.

All electromagnetic locks are fail safe because they are always
unlocked when disconnected from the power source. Using a battery
back-up does not make an electromagnetic lock fail secure because
the magnet would still be unlocked if the power was disconnected.
Later in this article it should become apparent why this detail
is important for reasons of life safety.

Electromechanical locks include standard cylindrical or mortise
locks that have been electrified and locks that are designed to
only work electrically, such as an electric bolt lock. They are
sold in equal amounts fail safe and fail secure.

Electrified exit devices come in a variety of functions, including
those with electric latch retraction and those with electrified outside
trim control. Electric latch retraction devices are fail secure whereas
exit devices with electrified exterior trim control might be either
fail safe or fail secure.

Application

Electric Strikes

Fail safe electric locking devices are used wherever doors must remain
unlocked in the event of a fire or other life safety emergency. If
the opening is fire rated, it must be positively latched by a fire
rated device in the event of a fire. Therefore there is no such thing
as a fire rated fail safe electric strike because if the power were
off (as it might very well be during a fire) the door would not be
positively latched. If you install a fail safe electric strike on
a fire rated opening, the inspector can require you to replace the
entire doorframe.

Technically, fire rated door frames cannot be modified in the field,
but must be prepared for hardware (including architectural grade electrified
hardware) in a fire rated shop. I have never heard of this being enforced,
nevertheless, the AHD (Authority Having Jurisdiction) could enforce
it, so if you plan to modify a fire rated opening in any way it might
be a good idea to get the local fire marshal on board during the planning
stages.

In general, a fail safe electric strike is a good choice for a “non-fire-rated
door that must be unlocked in the event of an emergency other than
a fire” kind of application.

Fail secure electric strikes are a good choice for exterior or other
non-fire-rated doors where remote release or electronic access control
is needed. They are pretty reliable, usually not difficult to install,
and relatively inexpensive. One of the chief disadvantages of an electric
strike is that, on out-swinging doors, they provide an opening into
which a burglar can insert a tool, such as a tire iron, to pry directly
on the locking device. A latch guard is a minimally effective deterrent
to this kind of attack.

(Exterior doors are almost never fire rated, and if they are, usually
it is because all the doors on the job were ordered to the same spec,
not because they have to be.)

Electromagnetic Locks

Some inspectors and fire marshals just don’t like electromagnetic
locks. This is another reason to get your local AHD on board from
the start. But if your AHD is not an obstacle, a mag can be a good
solution for existing fire rated doors with existing fire rated hardware
on them. The fire rated hardware can stay to keep the door positively
latched in the event of a fire, and the mag is inherently fail safe,
so it could be a good choice for stairwell doors, greatly simplifying
the application. The problem with mag locks is that they lock both
sides of the door simultaneously. That means you have to deal with
both a means to get in (access control) and a means to get out (presence
detector and redundant exit pushbutton, for example).

If the door already has an exit device, it is probably possible to
install a request-to-exit (RX) switch in the bar to allow exit by
a fully mechanical means – a factor which might make the AHD happier
with the installation. The AHD will also want to know that all electromagnetic
locks are wired so that the fire alarm will cut power to them in the
event of a fire.

Since a mag lock does not positively latch, it cannot be legally
used alone on a fire rated door. There must be a fire rated positively
latching mechanism in addition to the mag.

Delayed egress electromagnetic locks can also be used for access
control on egress doors while helping to prevent unauthorized exit.
For more information on delayed egress, please visit:

Electromagnetic locks are not too expensive and are very easy to
install. Because they are inherently fail safe, you may want to install
a battery back-up system so that they remain locked during routine
power outages.

Electromechanical Locks

Fail safe electrified standard locks are ideal for stairwell doors
(unless they already have exit devices) because they remain positively
latched when unlocked. Many states and localities require that stairwell
doors be unlocked in the event of a fire, and because all interior
stairwell doors are fire rated, they must also remain positively latched.

In order to replace a standard mechanical lock with an electrified
one, a raceway must be drilled through the door from lock side to
hinge side so that wire can be run to power the lock. If you guessed
that, technically speaking, this voids the fire rating on a fire rated
door, you were correct. Be sure to clear all modifications to fire
rated openings in advance with the local AHD.

Electric bolts are usually used as a last resort when no other application
will work, such as when retrofitting access control to automatic sliding
doors. Electric bolts are most commonly used in prisons, where egress
concerns are treated rather differently than commercial applications.
They can also be used in place of electromagnetic locks, however electric
bolts designed for commercial (rather than detention) applications
are less secure, less durable and more difficult to install than mag
locks.

Electrified Exit Devices

If a door has an existing exit device or an architect has specified
an exit device for an opening, it is because the capacity of the building
in terms of the number of people therein warrants the use of an exit
device. Therefore it is unwise to replace an exit device with another
kind of hardware.

Luckily, many exit devices can be electrified in the field either
by replacing internal parts of the device or by adding an electrified
trim (outside handle or lever).

As I mentioned earlier, exit devices can be electrified in one of
two ways:

Electric latch retraction
Electrified outside trim

Since electric latch retraction is always fail secure, it might not
be a good choice for stairwell doors unless it was always unlocked
from the stairwell side. If that were the case, the only probable
purpose for the electric latch retraction would be to unlatch the
door for a power operator (automatic door opener).

Electric latch retraction is ideal on exterior pairs of doors where
fail secure access control is required. Since exterior pairs of doors
are often equipped with concealed vertical rod exit devices, installing
electric latch retraction is often the easiest and best alternative.
Electric latch retraction (or electric remote dogging) is also very
compatible for use with power operators.

The down side of electric latch retraction, in addition to being
expensive in its own right, is that it often requires a special and
expensive power supply. Sargent 56 prefix exit devices are an exception,
requiring only a minimal power supply for activation.

Fail safe electrified exit device trim is a good alternative for
stairwell doors whether they already have an exit device or not. For
one thing, since the wire powering the trim is run through the exit
device, no modification of the fire rated door is necessary.

Electrified exit device trim is also available fail secure, and is
often a less expensive alternative to electric latch retraction where
simple access control is the goal.

Note on “Continuous Duty”

I have been asked, ‘What is the difference between fail safe and
continuous duty?’ Fail safe applies to the function of the device
as described above whereas continuous duty simply means the strike
is built to be constantly powered if so required. The confusion arises,
I think, because all fail safe locking devices are continuous duty.
This is because a fail safe device must have power to be locked. Fail
secure electric strikes that are connected to a timer and powered
all day to remain unlocked also must be continuous duty rated. Therefore,
not all continuous duty electric strikes are fail safe, but all fail
safe strikes are continuous duty.

Rule of thumb: almost every kind of electric locking device that
runs on DC current is continuous duty.