UL325-2016
*NORMALLY CLOSED - ENTRAPMENT PROTECTION
UL 325-2016 Standard for Safety
Frequently Asked Questions
Transition to UL 325-2016 - effective for gate operators
manufactured after January 11, 2016
2 of 8 UL325-2016 
What UL 325 changes become mandatory on January 12, 2016?
A: Not much and a lot. The primary change now mandates that all external sensors intended to protect against
entrapment must be monitored for presence and correct operation at least once per gate cycle. Since 2000, UL
325 required that gate operators have two independent means of entrapment protection, which serve to protect
the open and close directions of gate travel. However, there is a broad exception to monitored entrapment
protection for barrier arm gates where the arm does not move within close proximity to a rigid object. For most
gate operators, one of the two required means of protection is the Inherent Sensor (Type A) within the gate
operator and the second means of entrapment protection is typically the external sensor(s) that are installed at
the time of system installation. Any external entrapment protection sensor that protects against entrapment in
the open and/or close directions of gate travel must be monitored by the gate operator for presence and correct
operation. A constant hold input will be required if an entrapment protection sensor is not installed or has failed.
The constant hold input, such as from a three-button station, ensures that the person pushing the button is
monitoring the entrapment zones.
Q How many external entrapment protection sensors (as a combination of photo eyes and
edge sensors) are required in a typical automated gate installation?
A: That depends on the number of entrapment zones that must be protected. Most of the time, a minimum of
two external entrapment protection sensors will be required. Typically, this will be one sensor to protect against
entrapment in the open direction of gate travel and one sensor for the closed direction of gate travel. Swing gate
applications require only one external sensor, unless other entrapment zones exist. If you use edge sensors on a
swing gate, HySecurity recommends use of a wraparound edge sensor which serves to protect in both directions
of travel. Some sliding gate configurations may allow installation of one long-range photo eye to protect the
entire travel area of a slide gate. UL 325 sets a minimum standard that both directions of slide gate travel must
be protected with external sensors, however the installer must assess each specific site and install sensors that
protect all potential entrapment zones.
Q What external entrapment protection sensors do I need to install to meet the minimum
requirements for the gate operator to open and close under normal operation?
A: Normal operation allows momentary inputs and all automatic features. If the minimum number of sensors are
no t installed or a sensor has failed, a constant hold input will be required. See chart below:
How to meet the minimum requirement for Normal Operation†
Operator Type Single Sensor Method Two Sensor Method
Slide  Photo Eye, long range, to span both directions of gate
travel (powerful through beam Photo Eye required)
 Photo Eye Open & Photo Eye Close OR
 Edge Sensor Open & Edge Sensor Close OR
 Photo Eye Open & Edge Sensor Close OR
 Edge Sensor Open & Photo Eye Close
Swing
 Photo eye Close
 Edge sensor (wrap around type) for both directions of
gate travel (requires Miller MGR or MGS edge)
 Edge Sensor Open or Edge Sensor Close
 Optional
Vertical Lift  Photo Eye Close OR Edge Sensor Close  Optional
Barrier Arm N/A (not required when there is no risk of entrapment from barrier arm, provided that the barrier arm
does not close within 16" of a rigid object.) Sensors used for "object" detection do not require monitoring.
† Normal operation allows momentary inputs and all automatic features. If any direction of gate travel is not protected with a sensor,
that direction will require a constant hold command.
ONLY the Sensors and Accessories Listed Below are Approved
by HySecurity and UL or ETL for External Entrapment Protection Use
HySecurity Approved SENSORS
Frequently asked questions about UL 325-2016, which requires external
monitored entrapment protection sensors - effective for gate operators
manufactured after January 11, 2016
What choices did manufacturers have in order to comply with the UL 325 mandate for
monitored sensors? Did it require significant changes to their operators?
A: Manufacturers had a choice of three different routes to monitor external sensors
for presence and proper operation.
a. Connecting sensors to gate operators with a NC (Normally Closed) circuit.
b. Detecting a frequency or pulse generated by the sensor (2 or 4 wire).
c. Detecting a resistor, typically 10kΩ which allows a small current to bleed
through the circuit.
Each of these methods has advantages and disadvantages. HySecurity selected the
NC, Normally Closed solution to monitor external sensors because it allowed use of
the existing Smart Touch and Smart DC control boards with no hardware changes
whatsoever and minimal software adaptations, thus allowing the use of the same
boards that our customers have become familiar with over many years. More details
at the end of this FAQ.
Q How many monitored external sensors can I connect to a HySecurity gate operator?
A: All HySecurity control boards have three function programmable external entrapment sensor inputs. The inputs
are marked Sensor 1, Sensor 2 and Sensor 3. Only one sensor can be connected to each input, so a maximum
of three external sensors can be used. If you need to have more external sensors, an adapter made by Miller Edge
named The Solution (part number MIM-62) can be added. The Solution module has six inputs and two outputs,
which will be wired to HySecurity’s Sensor 1 and Sensor 2 inputs. Together with the still available Sensor 3 input,
the maximum number of external sensors that can be connected is seven.
Q Since an edge sensor is a normally open (NO) contact, how is it possible to monitor this?
A1: Miller Edge has modified their edge sensors to add a 10k Ohm resistor across the end of the edge opposite
the wire connection. This resistor allows a small current to pass through the edge which is how the edge will be
monitored. This change also means that old edge sensors without the 10k Ohm resistor cannot be monitored,
therefore you must be certain to buy edge sensors with a 10k resistor. Miller Edge will mark all edges with a 10k
Ohm resistor with a blue band of tape on the wire near the edge.
A2: If you do not use a Wireless Link Kit and instead wire the edge directly to the operator, you will also need to
add an interface module - Miller Edge part number GEM-104. Each edge sensor must have a 10k Ohm resistor
and be connected to a GEM-104 module, which monitors the 10k Ohm resistor in the edge sensor and outputs
a normally closed (NC) contact. The GEM module output will be connected to one of the three Sensor inputs on
HySecurity’s control board (either Smart Touch or Smart DC controller).
A3: If the edge sensor is to be transmitted to the gate operator, you won’t need the GEM-104 module, but instead
a Wireless Link Kit will be required. The Wireless Link Kit is Miller Edge part number MGL-K20, which includes a
receiver (MGL-RX20) and a transmitter (MGL-TX20). If you plan to transmit two edge sensors, such as the leading
end and trailing end of a slide gate, you’ll need an additional transmitter (MGL-TX20). Only one receiver is needed
because the receiver (MGL-RX20) has two input/output channels.
Q Can the warn-before-operate audio alert be used as one of the UL 325 Entrapment
Protection devices?
A: No. A warn-before-operate audio alert is no longer designated by UL 325 as an acceptable Entrapment
Protection device. However, most HySecurity operators are built with a programmable warn-before-operate audio
alert and we strongly recommend its use as an additional warning against potential entrapment.
*NORMALLY CLOSED - ENTRAPMENT PROTECTION
4 of 8 UL325-2016 
Q Can I use the new blue-taped Miller edges with a 10k Ohm resistor on 2015 and older
gate operators without a monitoring circuit?
A: No. For 2015 and older gate operators, you must be certain to add the GEM-104 module as an interface or
buy edge sensors without the 10k Ohm resistor. Directly connecting an edge sensor, with a 10k Ohm resistor, to
HySecurity’s controller is likely to falsely trigger the Edge sensor input.
If an installer uses blue-taped 10K resistor Miller Edges on pre-2016 HySecurity gate operators, the installer must
connect the Edge to a GEM-104 module and set the HySecurity Installer Menu “GC” GATE EDGE to “1,” (Normally
Closed).
Note: In pre-2016 gate operators, the GATE EDGE menu defaults to N.O. (Normally Open).
Q I normally installed edges sensors on the leading and trailing end of a sliding gate. Isn’t
that the best way to protect against entrapment?
A: Not necessarily. While the leading and trailing ends of a sliding gate are within potential entrapment zones,
the risk of entrapment, death or serious injury is high at the “Draw-In” zones. Common installer practice has been
to prioritize installation of edge sensors on both ends of a sliding gate, while not protecting the “Draw-In” zones
where the gate travels past a rigid object such as a wall, gate support posts or stationary fences. See slide gate
illustration below:
Most common areas requiring entrapment protection
Installers must assess each specific site and
install sensors that protect all potential entrapment zones.
www.hysecurity.com 
What happens if one of the external Entrapment Protection sensors becomes
disconnected or fails in a HySecurity Gate Operator?
A: The operator will stop cycling in automatic mode. The gate operator monitors the “Presence” and “Correct
Operation” of each entrapment protection sensor. When the operator no longer detects a properly functioning
sensor, it will cease automatic operation only in the direction of the missing or failed sensor. The operator will still
function, but only with a “Constant Hold Input” from an access control device.
Q What photo eyes and edge sensors are approved for use with HySecurity gate operators?
A: See list below. This list will change as new products come to market and are tested for use with HySecurity gate
operators. See updated lists on HySecurity’s website, on labels affixed to HySecurity gate operator boxes and in
HySecurity gate operator installation manuals.
How to meet the minimum requirement for Normal Operation†
Operator Type Single Sensor Method Two Sensor Method
Slide  Photo Eye, long range, to span both directions of gate
travel (powerful through beam Photo Eye required)
 Photo Eye Open & Photo Eye Close OR
 Edge Sensor Open & Edge Sensor Close OR
 Photo Eye Open & Edge Sensor Close OR
 Edge Sensor Open & Photo Eye Close
Swing
 Photo eye Close
 Edge sensor (wrap around type) for both directions of
gate travel (requires Miller MGR or MGS edge)
 Edge Sensor Open or Edge Sensor Close
 Optional
Vertical Lift  Photo Eye Close OR Edge Sensor Close  Optional
Barrier Arm N/A (not required when there is no risk of entrapment from barrier arm, provided that the barrier arm
does not close within 16" of a rigid object.) Sensors used for "object" detection do not require monitoring.
† Normal operation allows momentary inputs and all automatic features. If any direction of gate travel is not protected with a sensor,
that direction will require a constant hold command.
ONLY the Sensors and Accessories Listed Below are Approved
by HySecurity and UL or ETL for External Entrapment Protection Use
HySecurity Approved SENSORS
Device Type Mfg. Part # Mfg. Usage HySecurity
Part #
Wraparound edge MGR20-2U-05-T2* Miller Edge 5’/2" round - w/10kΩ resistor MX3981
Wraparound edge MGS20-2U-05-T2* Miller Edge 5’/2" square - w/10kΩ resistor MX3982
Standard edge kit MGO20-2E-05-T2* Miller Edge 5’/1-½" - w/10kΩ resistor MX4037
Reflective photo eye kit E3K-R10K4-NR Omron 40' max range limit MX000999
Reflective photo eye Reflecti-Guard RG-R Miller Edge 25' max range limit MX3985
Thru-beam photo eye kit IRB-MON EMX 65' max range limit MX3990
Thru-beam photo eye kit IRB-325 EMX 50' max range limit MX000846
HySecurity Approved SENSOR ACCESSORIES
Wired edge module GEM-104* interface module Miller Edge Use one with each edge* MX3983
Wireless edge link MGL-TX20** Miller Edge Transmitter MX3986
Wireless edge link MGL-RX20** Miller Edge Receiver MX4013
Wireless edge link MGL-K20** Miller Edge Kit with transmitter & receiver MX4015
Multi-Input module The Solution - MIM-62** Miller Edge Input expansion >3 MX3987
* Edge sensors must have a 10kΩ resistor to be monitored and the GEM-104 interface module is required, when hard-wired
** GEM-104 is not required when edge sensors are paired with Wireless Edge Link or the Multi-Input Module
6 of 8 UL325 
Q Can any UL Recognized or ETL Listed sensor be installed with any UL or ETL Listed gate
operator?
A: No. In addition to UL component Recognition or an ETL Listing, a sensor must be tested together with the gate
operator in order to meet 2016 UL 325 Standard of Safety. According to Underwriter Laboratories:
You must consult your gate operator manual to determine the components that are tested and approved for use
with that specific gate operator. All entrapment protection sensors, such as photo eyes and edge sensors, must
be tested by UL, ETL or another Independent Test Laboratory. Successfully passing a UL component test allows the
component manufacturer to “Mark” the product with a label that looks like one of these:
UL Recognized
This UL logo indicates that
the component, in this case
an EMX photo eye, was tested
by UL and met the UL325
standard for photo eyes.
ETL Listed
This circular ETL LOGO with
a registration number below
indicates that the component, in
this case an EMX photo eye, was
tested by Intertek and met the
UL325 standard for photo eyes.
However, neither “UL Recognized” nor “ETL Listed” as above fully qualifies a component to be used with a gate
operator. Each sensor, brand and model, must still pass another test proving compatibility and functionality when
connected to a UL 325 Listed or ETL Listed gate operator. All gate operator manufacturer’s installation instructions
must list the sensors which are approved for connection to their gate operators.
Q Will there be a time when all UL 325 Recognized or ETL Listed sensors will qualify them
for use with any UL or ETL listed gate operator?
A: Possibly, but not today. Underwriter Laboratories and Industry organizations are currently considering a CEI,
Common External Interface proposal. Adoption of this proposed standard addition could preclude the need for
the additional gate operator specific test of those devices. Component and gate operator manufacturers will
announce if and when such a change to the UL 325 standard is adopted.
Q Do gate operators manufactured prior to January 12, 2016 require Monitored
Entrapment Protection Sensors?
A: No. Monitoring of external entrapment protection sensors is only required when the gate operator is
manufactured after January 11, 2016. However, it has always been the installers’ and end users’ responsibility to
ensure that sufficient external entrapment protection sensors are installed to protect all entrapment zones, even if
that demands more than the minimum UL 325 requirement.
If a 2015 or older HySecurity Smart Touch or Smart DC board requires replacement, do I
need to change the installation to comply with the new UL 325 2016 standard?
A: No. The requirements of the UL Standard are not retroactive to older operators. HySecurity’s control boards
and software manufactured in 2016 and thereafter will be backwards compatible with pre-2016 HySecurity gate
operators.
HySecurity Smart Touch & Smart DC Control
Boards didn’t change. They are backwards
compatible with pre-2016 operators.
Q Will I have to update previous installs or gate operators manufactured prior to 2016 to
meet the requirements for Monitored Entrapment Protection Sensors?
A: No. Monitoring of external entrapment protection sensors is only required when the gate operator is
manufactured on or after January 12, 2016.
Q Can I update an older HySecurity operator to meet the new 2016 UL 325 standard?
A: Yes, Very easily. Just upload new software version h4.50 (Smart Touch) or h5.50 (Smart DC) or later and add the
necessary entrapment protection sensors that have been tested and approved by HySecurity.
Q Does HySecurity recommend any specific type of edge sensors in certain applications?
A: Yes, HySecurity recommends Miller Edge Wraparound style edge sensors (MGS or MGR) on the leading end of a
swing gate with a 2” frame. HySecurity makes this recommendation because these Wraparound style edge sensors
allow one edge sensor to protect in both the open and close directions of swing gate travel. If your swing gate
frame cannot fit 2” wraparound edge sensors, you will need to use at least two standard edge sensors.
Q What UL 325 inspired changes may impact my external sensor choices?
A: The UL 325 requirement for monitoring external sensors means that a monitored wireless transmitter/
receiver will be required for any edge sensor that is not directly wired into the gate operator. Many installers
have in the past used a simple edge transmitter with a standard receiver for wireless edge sensors, but the older
edge transmitter/receiver cannot be monitored, so new monitored wireless transmitter/receiver hardware will
be required. This is because ALL external entrapment protection sensors MUST now be monitored by the gate
operator. The expense and complexity of a monitored wireless transmitter/receiver may mean that some installers
decide to change their installation practices and choose locations for edge sensors that can be wired directly into
the gate operator. Some installers may develop a preference to use photo eyes as entrapment protection sensors,
because a photo eye may be easier to install and monitor than an edge sensor and because a photo-eye offers
non-contact protection.
Call HySecurity for an operator/parts distributor near you.
phone 800-321-9947 fax 888-321-9946
www.hysecurity.com • info@hysecurity.com
D0728 030716
Q In the past, I’ve had issues with photo eyes, especially reflective photo eyes that have
falsely held a gate open. Is there something that I can do to assure of reliable photo eye
performance?
A: Yes. Not all photo eyes are created equal. Be very careful about trusting the published photo eye maximum
range. Manufacturers frequently do not tell the whole story when publishing the maximum range of their photo
eyes. This is especially true for reflective style photo eyes. A photo eye must have significant “excess gain” to
ensure reliability in outdoor applications, because fog, ice, snow and dirty optical surfaces all occur normally in
outdoor environments. Unfortunately, most photo eye manufacturers do not publish their “excess gain” charts.
They generally publish only a theoretical maximum range, which may suffice for indoor use. Be conservative when
using photo eyes with longer gates. As a quick rule, limit the distance that you use a photo eye in an outdoor
application to a maximum, of 75% of manufacturers’ published range. Some photo eyes only reliably operate at
50% of their published range. If your gate location is subject to occasional heavy fog, we recommend you limit the
distance spanned by a photo eye to 50% of its published range. The photo eyes approved for use with HySecurity
Gate Operators are shown in the table above with our conservative ranges, based on the manufacturers’
specifications
Q If I download a software update from HySecurity into a pre-2016 gate operator, won’t
that force me to update to comply with UL 325 – 2016 and add monitored entrapment
protection sensors?
A: No. HySecurity has added a special configuration menu into our software that will appear when loading our
new software into a pre-2016 operator. This new menu will prompt the installer to enter the Build Year [BY x]
and a by entering a setting of [BY 1] all future software will function the same as if it was a pre-2016 operator. If
you wanted to update the operator, set the Build Year to [BY 2] and the operator will be configured as a post
2016 operator - it’s that simple!. Of course, you will also have to add the required number of approved external
entrapment protection sensors, which will be monitored.
Q Why did HySecurity choose the Normally Closed (NC) method to monitor external
entrapment protection sensors?
A: There were many good reasons that HySecurity choose Normally Closed (NC) monitoring.
1. This design allowed use of the existing Smart Touch and Smart DC control boards with no hardware
changes whatsoever and minimal software adaptations.
2. Normally Closed (NC) monitoring allows the broadest selection of external sensors. Expect our list of
authorized sensors to expand over time.
3. Since our Smart control boards cycle device power as part of the Normally Closed (NC) monitoring, they
also turn off all power to the external sensors when the operator is not moving the gate. This energy
savings is very important for all DC operators with UPS (battery backup) and extremely important for solar
gate operators.
4. Normally Closed (NC) monitoring is safe and true monitoring because it fully tests the entire circuit and
function of the device. We note that a for those using resistance monitoring that a 10kΩ resistor at the
termination of a photo-eye may not be able to detect any internal problems with the photo-eye and may
not detect a fault when the power to the photo-eye has been disconnected.
Visit www.hysecurity.com/gatesafety for more information
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