NEW REQUIREMENT AIMS TO ELIMINATE ENTRAPMENT UL
325
By Joel Hawk and John Hupfauer
HOMEOWNERS HAVE BEEN KNOWN TO LEAVE THEIR GARAGE
DOORS partially open instead of the usual fully open/fully closed
positions. The reasons vary, but include ventilation purposes and to
provide access for pets to come and go freely. What is the safety impact
of a partially open garage door?
Leaving a garage door partially open is not uncommon. As this use has
become more widespread, it raises the concern whether attempts to squeeze
under a stationary, partially open garage door could result in entrapment.
If an electrical garage door operator is activated remotely or
unintentionally, there may be increased risk to a pinned individual if the
door travels further in the closing direction or an operator is
unresponsive upon user activation of the control.
Why would a door travel in an undesired direction or not open upon
control activation? Depending upon how the user arranged the partially
open condition (stop on close or stop on open), the operator may seek to
continue in the interrupted direction. Successfully activating the control
could conceivably make the situation worse.
In an emergency situation, the rescuing individual may panic and press
control buttons multiple times in rapid succession. This form of input
could be misinterpreted by the logic of the door operator. What does the
electronic network do when provided with a unique sequence of commands? It
may do nothing or operate in a manner that worsens the situation.
Current Standards
Residential garage door operators are subject to the safety
requirements of the Standard for Door, Drapery, Gate, Louver, and Window
Operators and Systems, American National Standards Institute (ANSI)/UL
325. The first edition of ANSI/UL 325 was published in April 1973, with
the first UL Listed residential garage door operator established in that
same year. Technology has advanced substantially since the days of
discrete electronic devices and simple integrated circuits.
User familiarity with the now widespread usage of garage door operators
can and has reduced the degree of caution exercised when the technology
was not so widespread. As usage and technology has evolved, so did the
safety requirements to reflect advanced safety capabilities and potential
hazards arising from user behavior.
UL 325 has always required a residential garage door operator to stop
closing if an obstruction is detected in the path of the door. The
inherent primary entrapment protection reacts upon direct contact of an
obstruction. In addition, UL 325 and U.S. federal law have required the
system to incorporate a supplementary detection means since 1993.
In February, the Standards Technical Panel (STP) for ANSI/UL 325
published new entrapment protection requirements in response to potential
hazards associated with partially open residential garage doors. The UL
325 STP is an important part of the process by which UL develops and
maintains its Standards for Safety. An STP is a group of individuals,
representing a variety of interests, formed to review proposals related to
UL Standards for Safety. When an ANSI/UL Standard for Safety is involved,
an STP serves as the consensus body to review and vote on proposals prior
to publication.
New Requirements
What are the new requirements? To relieve a pinned person or pet under
a partially open door, UL 325 now requires a door starting from a
partially open position to stop and then raise a minimum of 2 inches when
an obstruction is detected. This is intended to assure that the door will
not further pin an individual as well as provide sufficient clearance to
release the pinned individual. Once the door stops at its preset distance
(2 or more inches), and the obstruction is removed and no longer detected,
normal operation is restored. The door operator is subsequently capable of
repeating this safety function should the need arise.
Requirements addressing the partially open residential garage door
condition become effective for all Listed garage door operators after
February 21, 2008. Installation instructions shalL indicate the entrapment
protection means suitable for the operating system to assure that the
entrapment protection components, such as photo-eye and edge sensors, are
compatible with the operating system. Systems should be maintained in
operable condition, and repairs, if necessary, should be made using
components described in the original Listing.
Methods of validating the proper function of these new features after
installation may vary depending on the system and entrapment protection
technology used. For example, photo-eyes may simply be blocked to simulate
an obstruction while an edge sensor may require a compression force. Other
specialized sensory means may require more unique approaches to simulate
an obstruction. Installation and user instructions indicate how to
properly install and maintain the operating system as well as provide
guidance on how to test the system for its entrapment protection
capabilities.
UL 325 benefits from a commitment to public safety by the experts who
actively participate in the standards development process. Manufacturers
understand the value of third-party certification to demonstrate to
installers and users that they comply with nationally recognized safety
standards. Since the first UL certification in 1973 confirmed compliance
with the safety requirements, millions of garage door openers have been
safely installed and operated, all the while adapting to ever changing
user behavior and advances in technology.
Joel Hawk is a principal engineer with Underwriters Laboratories
Inc. John Hupfauer is a staff engineering associate for Underwriters
Laboratories. For more information on UL 325, call 847.272.8800; visit www.ul.com.
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