General Safety & Health Standards |
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| Powered Platforms
Chapter 296-24 WAC, Part J-3
(Continued) |
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Note: The elevated platform requirements for the general and construction industries have been moved to chapter 296-869 WAC, Elevating Work Platforms
Note: The powered platform requirements for the general and construction industries have been moved to chapter 296-870 WAC, Powered Platforms.
Appendix C in section 296-24-88050 still applies.
WAC 296-24-88050
Appendix C — Personal fall arrest system (Part I —
Mandatory; Parts II and III — Nonmandatory).
(1) Use of the Appendix.
Part I of Appendix C sets out the mandatory criteria for personal
fall arrest systems used by all employees using powered platforms.
Part II sets out nonmandatory test procedures which may be used
to determine compliance with applicable requirements contained
in Part I of this Appendix. Part III provides nonmandatory guidelines
which are intended to assist employers in complying with these
provisions.
PART I
Personal fall arrest systems (mandatory) -- (1) Scope and application.
This section establishes the application of and performance criteria
for personal fall arrest systems which are required for use by
all employees using powered platforms under WAC 296-24-88035.
(2) Definitions.
Anchorage means a secure point of attachment for lifelines,
lanyards, or deceleration devices which is capable of withstanding
the forces specified in the applicable sections of chapter 296-24
WAC, and independent of the means of supporting or suspending
the employee.
Buckle means any device for holding the body harness closed
around the employee's body.
Competent person means an individual knowledgeable of fall protection
equipment, including the manufacturers recommendations and instructions
for the proper use, inspection, and maintenance; and who is capable
of identifying existing and potential fall hazards; and who has
the authority to take prompt corrective action to eliminate those
hazards; and who is knowledgeable of the rules contained in this
section regarding the erection, use, inspection, and maintenance
of fall protection equipment and systems.
Connector means a device which is used to couple (connect) parts
of the personal fall arrest system and positioning device systems
together. It may be an independent component of the system, such
as a carabiner, or it may be an integral component of part of
the system (such as a buckle or dee-ring sewn into a body belt
or body harness, or a snap-hook spliced or sewn to a lanyard or
self-retracting lanyard).
Deceleration device means any mechanism, such as a rope grab,
ripstitch lanyard, specially woven lanyard, tearing or deforming
lanyards, automatic self retracting-lifeline/lanyard, etc., which
serves to dissipate a substantial amount of energy during a fall
arrest, or otherwise limit the energy imposed on an employee during
fall arrest.
Deceleration distance means the additional vertical distance
a falling employee travels, excluding lifeline elongation and
free fall distance, before stopping, from the point at which the
deceleration device begins to operate. It is measured as the distance
between the location of an employee's full body harness attachment
point at the moment of activation (at the onset of fall arrest
forces) of the deceleration device during a fall, and the location
of that attachment point after the employee comes to a full stop.
Equivalent means alternative designs, materials or methods to
protect against a hazard which the employer can demonstrate will
provide an equal or greater degree of safety for employees than
the methods, materials or designs specified in the standard.
Free fall means the act of falling before a personal fall arrest
system begins to apply force to arrest the fall.
Free fall distance means the vertical displacement of the fall
arrest attachment point on the employee's body harness between
onset of the fall and just before the system begins to apply force
to arrest the fall. This distance excludes deceleration distance,
and lifeline lanyard elongation, but includes any deceleration
device slide distance or self-retracting lifeline/lanyard extension
before they operate and fall arrest forces occur.
Full body harness means a configuration of connected straps
to distribute a fall arresting force over at least the thighs,
shoulders and pelvis, with provisions for attaching a lanyard,
lifeline, or deceleration device.
Lanyard means a flexible line of webbing, rope, or cable used
to secure a body belt or harness to a lifeline or an anchorage
point usually 2, 4, or 6 feet long.
Lifeline means a vertical line from a fixed anchorage or between
two horizontal anchorages, independent of walking or working surfaces,
to which a lanyard or device is secured. Lifeline as referred
to in this text is one which is part of a fall protection system
used as back-up safety for an elevated worker.
Personal fall arrest system means a system used to arrest an
employee in a fall from a working level. It consists of an anchorage,
connectors, body harness and may include a lanyard, deceleration
device, lifeline, or suitable combinations of these.
Qualified means one who, by possession of a recognized degree,
certificate, or professional standing, or who by extensive knowledge,
training, and experience, has successfully demonstrated his/her
ability to solve or resolve problems related to the subject matter,
the work, or the project.
Rope grab means a fall arrester that is designed to move up
or down a lifeline suspended from a fixed overhead or horizontal
anchorage point, or lifeline, to which the belt or harness is
attached. In the event of a fall, the rope grab locks onto the
lifeline rope through compression to arrest the fall. The use
of a rope grab device is restricted for all restraint applications.
Self-retracting lifeline/lanyard means a deceleration device
which contains a drum-wound line which may be slowly extracted
from, or retracted onto, the drum under slight tension during
normal employee movement, and which after onset of a fall, automatically
locks the drum and arrests the fall.
Snap-hook means a self-closing connecting device with a gatekeeper
latch or similar arrangement that will remain closed until manually
opened. This includes single action snap hooks that open when
the gatekeeper is depressed and double action snap hooks that
require a second action on a gatekeeper before the gate can be
opened.
Tie-off means the act of an employee, wearing personal fall
protection equipment, connecting directly or indirectly to an
anchorage. It also means the condition of an employee being connected
to an anchorage.
(3) Design for system components.
(a) Connectors must be drop forged, pressed or formed steel,
or made of equivalent materials.
(b) Connectors must have a corrosion-resistant finish, and all
surfaces and edges must be smooth to prevent damage to interfacing
parts of the system.
(c) Lanyards and vertical lifelines which tie-off one employee
must have a minimum breaking strength of 5,000 pounds (22.2 kN).
(d) Self-retracting lifelines and lanyards which automatically
limit free fall distance to 2 feet (0.61 m) or less must have
components capable of sustaining a minimum static tensile load
of 3,000 pounds (13.3 kN) applied to the device with the lifeline
or lanyard in the fully extended position.
(e) Self-retracting lifelines and lanyards which do not limit
free fall distance to 2 feet (0.61 m) or less, ripstitch lanyards,
and tearing and deforming lanyards must be capable of sustaining
a minimum tensile load of 5,400 pounds (23.9 kN) applied to the
device with the lifeline or lanyard in the fully extended position.
(f) Dee-rings and snap-hooks must be capable of sustaining a
minimum tensile load of 5000 pounds (22.2 N).
(g) Dee-rings and snap-hooks must be 100 percent proof-tested
to a minimum tensile load of 3600 pounds (16 kN) without cracking,
breaking, or taking permanent deformation.
(h) Snap-hooks must be sized to be compatible with the member
to which they are connected so as to prevent unintentional disengagement
of the snap-hook by depression of the snap-hook keeper by the
connected member, or must be a locking type snap-hook designed
and used to prevent disengagement of the snap-hook by the contact
of the snap-hook keeper by the connected member.
(i) Horizontal lifelines, where used, must be designed, and
installed as part of a complete personal fall arrest system, which
maintains a safety factor of at least 2, under the supervision
of a qualified person.
(j) Anchorages to which personal fall arrest equipment is attached
must be capable of supporting at least 5,000 pounds (22.2 kN)
per employee attached, or must be designed, installed, and used
as part of a complete personal fall arrest system which maintains
a safety factor of at least two, under the supervision of a qualified
person.
(k) Ropes and straps (webbing) used in lanyards, lifelines,
and strength components of body harnesses, must be made from synthetic
fibers or wire rope.
(4) System performance criteria.
(a) Personal fall arrest systems must, when stopping a fall:
(i) Limit maximum arresting force on an employee to 1,800 pounds
(8 kN) when used with a body harness;
(ii) Bring an employee to a complete stop and limit maximum
deceleration distance an employee travels to 3.5 feet (1.07 m);
and
(iii) Must have sufficient strength to withstand twice the potential
impact energy of an employee free falling a distance of 6 feet
(1.8 m), or the free fall distance permitted by the system, whichever
is less.
(b)(i) When used by employees having a combined person and tool
weight of less than 310 pounds (140 kg), personal fall arrest
systems which meet the criteria and protocols contained in subsections
(2), (3), and (4) in Part II of this Appendix must be considered
as complying with the provisions of (a) of this subsection.
(ii) When used by employees having a combined tool and body
weight of 310 pounds (140 kg) or more, personal fall arrest systems
which meet the criteria and protocols contained in subsections
(2), (3), and (4) of Part II may be considered as complying with
the provisions of (a) of this subsection provided that the criteria
and protocols are modified appropriately to provide proper protection
for such heavier weights.
(5) Care and use.
(a) Snap-hooks, unless of a locking type designed and used to
prevent disengagement from the following connections, must not
be engaged:
(i) Directly to webbing, rope or wire rope;
(ii) To each other;
(iii) To a dee-ring to which another snap-hook or other connector
is attached;
(iv) To a horizontal lifeline; or
(v) To any object which is incompatibly shaped or dimensioned
in relation to the snap-hook such that the connected object could
depress the snap-hook keeper a sufficient amount to release itself.
(b) Devices used to connect to a horizontal lifeline which may
become a vertical lifeline must be capable of locking in either
direction on the lifeline.
(c) Personal fall arrest systems must be rigged such that an
employee can neither free fall more than 6 feet (1.8 m), nor contact
any lower level.
(d) The attachment point of the body harness must be located
in the center of the wearer's back near shoulder level, or above
the wearer's head.
(e) When vertical lifelines are used, each employee must be
provided with a separate lifeline.
(f) Personal fall arrest systems or components must be used
only for employee fall protection.
(g) Personal fall arrest systems or components subjected to
impact loading must be immediately removed from service and must
not be used again for employee protection unless inspected and
determined by a competent person to be undamaged and suitable
for reuse.
(h) The employer must provide for prompt rescue of employees
in the event of a fall or must assure the self-rescue capability
of employees.
(i) Before using a personal fall arrest system, and after any
component or system is changed, employees must be trained in accordance
with the requirements of WAC 296-24-88030(1), in the safe use
of the system.
(6) Inspections. Personal fall arrest systems must be inspected
prior to each use for mildew, wear, damage and other deterioration,
and defective components must be removed from service if their
strength or function may be adversely affected.
PART II
Test methods for personal fall arrest systems
(nonmandatory)
(1) General. Subsections (2), (3), (4) and (5) of this Part II
set forth test procedures which may be used to determine compliance
with the requirements in subsection (4) of Part I of this Appendix.
(2) General conditions for all tests in Part II.
(a) Lifelines, lanyards and deceleration devices should be attached
to an anchorage and connected to the body harness in the same
manner as they would be when used to protect employees.
(b) The anchorage should be rigid, and should not have a deflection
greater than .04 inches (1 mm) when a force of 2,250 pounds (10
kN) is applied.
(c) The frequency response of the load measuring instrumentation
should be 120 Hz.
(d) The test weight used in the strength and force tests should
be a rigid, metal, cylindrical or torso-shaped object with a girth
of 38 inches plus or minus 4 inches (96 cm plus or minus 10 cm).
(e) The lanyard or lifeline used to create the free fall distance
should be supplied with the system, or in its absence, the least
elastic lanyard or lifeline available to be used with the system.
(f) The test weight for each test should be hoisted to the required
level and should be quickly released without having any appreciable
motion imparted to it.
(g) The system's performance should be evaluated taking into
account the range of environmental conditions for which it is
designed to be used.
(h) Following the test, the system need not be capable of further
operation.
(3) Strength test.
(a) During the testing of all systems, a test weight of 300
pounds plus or minus 5 pounds (135 kg plus or minus 2.5 kg) should
be used. (See subsection (2)(d) of this part.)
(b) The test consists of dropping the test weight once. A new
unused system should be used for each test.
(c) For lanyard systems, the lanyard length should be 6 feet
plus or minus 2 inches (1.83 m plus or minus 5 cm) as measured
from the fixed anchorage to the attachment on the body belt or
body harness.
(d) For rope-grab-type deceleration systems, the length of the
lifeline above the centerline of the grabbing mechanism to the
lifeline's anchorage point should not exceed 2 feet (0.61 m).
(e) For lanyard systems, for systems with deceleration devices
which do not automatically limit free fall distance to 2 feet
(0.61 m) or less, and for systems with deceleration devices which
have a connection distance in excess of one foot (0.3 m) (measured
between the centerline of the lifeline and the attachment point
to the body harness), the test weight should be rigged to free
fall a distance of 7.5 feet (2.3 m) from a point that is 1.5 feet
(46 cm) above the anchorage point, to its hanging location (6
feet below the anchorage). The test weight should fall without
interference, obstruction, or hitting the floor or ground during
the test. In some cases a nonelastic wire lanyard of sufficient
length may need to be added to the system (for test purposes)
to create the necessary free fall distance.
(f) For deceleration device systems with integral lifelines
or lanyards which automatically limit free fall distance to 2
feet (0.61 m) or less, the test weight should be rigged to free
fall a distance of 4 feet (1.22 m).
(g) Any weight which detaches from the harness should constitute
failure for the strength test.
(4) Force test.
(a) General. The test consists of dropping the respective test
weight specified in (b)(i) or (c)(i) of this subsection once.
A new, unused system should be used for each test.
(b) For lanyard systems.
(i) A test weight of 220 pounds plus or minus three pounds (100
kg plus or minus 1.6 kg) should be used. (See subsection (2)(d)
above.)
(ii) Lanyard length should be 6 feet plus or minus 2 inches
(1.83 m plus or minus 5 cm) as measured from the fixed anchorage
to the attachment on the body harness.
(iii) The test weight should fall free from the anchorage level
to its hanging location (a total of 6 feet (1.83 m) free fall
distance) without interference, obstruction, or hitting the floor
or ground during the test.
(c) For all other systems.
(i) A test weight of 220 pounds plus or minus 3 pounds (100
kg plus or minus 1.6 kg) should be used. (See subsection (2)(d)
above.)
(ii) The free fall distance to be used in the test should be
the maximum fall distance physically permitted by the system during
normal use conditions, up to a maximum free fall distance for
the test weight of 6 feet (1.83 m), except as follows:
(A) For deceleration systems which have a connection link or
lanyard, the test weight should free fall a distance equal to
the connection distance (measured between the centerline of the
lifeline and the attachment point to the body harness).
(B) For deceleration device systems with integral lifelines
or lanyards which automatically limit free fall distance to 2
feet (0.61 m) or less, the test weight should free fall a distance
equal to that permitted by the system in normal use. (For example,
to test a system with a self-retracting lifeline or lanyard, the
test weight should be supported and the system allowed to retract
the lifeline or lanyard as it would in normal use. The test weight
would then be released and the force and deceleration distance
measured).
(d) A system fails the force test if the recorded maximum arresting
force exceeds 2,520 pounds (11.2 kN) when using a body harness.
(e) The maximum elongation and deceleration distance should
be recorded during the force test.
(5) Deceleration device tests.
(a) General. The device should be evaluated or tested under
the environmental conditions, (such as rain, ice, grease, dirt,
type of lifeline, etc.), for which the device is designed.
(b) Rope-grab-type deceleration devices.
(i) Devices should be moved on a lifeline 1,000 times over the
same length of line a distance of not less than one foot (30.5
cm), and the mechanism should lock each time.
(ii) Unless the device is permanently marked to indicate the
type(s) of lifeline which must be used, several types (different
diameters and different materials), of lifelines should be used
to test the device.
(c) Other self-activating-type deceleration devices. The locking
mechanisms of other self-activating-type deceleration devices
designed for more than one arrest should lock each of 1,000 times
as they would in normal service.
PART III
Additional nonmandatory guidelines for personal fall arrest systems.
The following information constitutes additional guidelines for
use in complying with requirements for a personal fall arrest
system.
(1) Selection and use considerations. The kind of personal fall
arrest system selected should match the particular work situation,
and any possible free fall distance should be kept to a minimum.
Consideration should be given to the particular work environment.
For example, the presence of acids, dirt, moisture, oil, grease,
etc., and their effect on the system, should be evaluated. Hot
or cold environments may also have an adverse affect on the system.
Wire rope should not be used where an electrical hazard is anticipated.
As required by the standard, the employer must plan to have means
available to promptly rescue an employee should a fall occur,
since the suspended employee may not be able to reach a work level
independently.
Where lanyards, connectors, and lifelines are subject to damage
by work operations such as welding, chemical cleaning, and sandblasting,
the component should be protected, or other securing systems should
be used. The employer should fully evaluate the work conditions
and environment (including seasonal weather changes) before selecting
the appropriate personal fall protection system. Once in use,
the system's effectiveness should be monitored. In some cases,
a program for cleaning and maintenance of the system may be necessary.
(2) Testing considerations. Before purchasing or putting into
use a personal fall arrest system, an employer should obtain from
the supplier information about the system based on its performance
during testing so that the employer can know if the system meets
this standard. Testing should be done using recognized test methods.
Part II of this Appendix C contains test methods recognized for
evaluating the performance of fall arrest systems. Not all systems
may need to be individually tested; the performance of some systems
may be based on data and calculations derived from testing of
similar systems, provided that enough information is available
to demonstrate similarity of function and design.
(3) Component compatibility considerations. Ideally, a personal
fall arrest system is designed, tested, and supplied as a complete
system. However, it is common practice for lanyards, connectors,
lifelines, deceleration devices, and body harnesses to be interchanged
since some components wear out before others. The employer and
employee should realize that not all components are interchangeable.
For instance, a lanyard should not be connected between a body
harness and a deceleration device of the self-retracting type
since this can result in additional free fall for which the system
was not designed. Any substitution or change to a personal fall
arrest system should be fully evaluated or tested by a competent
person to determine that it meets the standard, before the modified
system is put in use.
(4) Employee training considerations. Thorough employee training
in the selection and use of personal fall arrest systems is imperative.
As stated in the standard, before the equipment is used, employees
must be trained in the safe use of the system. This should include
the following: Application limits; proper anchoring and tie-off
techniques; estimation of free fall distance, including determination
of deceleration distance, and total fall distance to prevent striking
a lower level; methods of use; and inspection and storage of the
system. Careless or improper use of the equipment can result in
serious injury or death. Employers and employees should become
familiar with the material in this Appendix, as well as manufacturer's
recommendations, before a system is used. Of uppermost importance
is the reduction in strength caused by certain tie-offs (such
as using knots, tying around sharp edges, etc.) and maximum permitted
free fall distance. Also, to be stressed are the importance of
inspections prior to use, the limitations of the equipment, and
unique conditions at the worksite which may be important in determining
the type of system to use.
(5) Instruction considerations. Employers should obtain comprehensive
instructions from the supplier as to the system's proper use and
application, including, where applicable:
(a) The force measured during the sample force test;
(b) The maximum elongation measured for lanyards during the
force test;
(c) The deceleration distance measured for deceleration devices
during the force test;
(d) Caution statements on critical use limitations;
(e) Application limits;
(f) Proper hook-up, anchoring and tie-off techniques, including
the proper dee-ring or other attachment point to use on the body
harness for fall arrest;
(g) Proper climbing techniques;
(h) Methods of inspection, use, cleaning, and storage; and
(i) Specific lifelines which may be used. This information should
be provided to employees during training.
(6) Inspection considerations. As stated in WAC 296-24-88050(6),
personal fall arrest systems must be regularly inspected. Any
component with any significant defect, such as cuts, tears, abrasions,
mold, or undue stretching; alterations or additions which might
affect its efficiency; damage due to deterioration; contact with
fire, acids, or other corrosives; distorted hooks or faulty hook
springs; tongues unfitted to the shoulder of buckles; loose or
damaged mountings; nonfunctioning parts; or wearing or internal
deterioration in the ropes must be withdrawn from service immediately,
and should be tagged or marked as unusable, or destroyed.
(7) Rescue considerations. As required by WAC 296-24-88050 (5)(h)
when personal fall arrest systems are used, the employer must
assure that employees can be promptly rescued or can rescue themselves
should a fall occur. The availability of rescue personnel, ladders
or other rescue equipment should be evaluated. In some situations,
equipment which allows employees to rescue themselves after the
fall has been arrested may be desirable, such as devices which
have descent capability.
(8) Tie-off considerations.
(a) One of the most important aspects of personal fall protection
systems is fully planning the system before it is put into use.
Probably the most overlooked component is planning for suitable
anchorage points. Such planning should ideally be done before
the structure or building is constructed so that anchorage points
can be incorporated during construction for use later for window
cleaning or other building maintenance. If properly planned, these
anchorage points may be used during construction, as well as afterwards.
(b) Employers and employees should at all times be aware that
the strength of a personal fall arrest system is based on its
being attached to an anchoring system which does not significantly
reduce the strength of the system (such as a properly dimensioned
eye-bolt/snap-hook anchorage). Therefore, if a means of attachment
is used that will reduce the strength of the system, that component
should be replaced by a stronger one, but one that will also maintain
the appropriate maximum arrest force characteristics.
(c) Tie-off using a knot in a rope lanyard or lifeline (at any
location) can reduce the lifeline or lanyard strength by 50 percent
or more. Therefore, a stronger lanyard or lifeline should be used
to compensate for the weakening effect of the knot, or the lanyard
length should be reduced (or the tie-off location raised) to minimize
free fall distance, or the lanyard or lifeline should be replaced
by one which has an appropriately incorporated connector to eliminate
the need for a knot.
(d) Tie-off of a rope lanyard or lifeline around an "H"
or "I" beam or similar support can reduce its strength
as much as 70 percent due to the cutting action of the beam edges.
Therefore, use should be made of a webbing lanyard or wire core
lifeline around the beam; or the lanyard or lifeline should be
protected from the edge; or free fall distance should be greatly
minimized.
(e) Tie-off where the line passes over or around rough or sharp
surfaces reduces strength drastically. Such a tie-off should be
avoided or an alternative tie-off rigging should be used. Such
alternatives may include use of a snap-hook/dee-ring connection,
wire rope tie-off, an effective padding of the surfaces, or an
abrasion-resistance strap around or over the problem surface.
(f) Horizontal lifelines may, depending on their geometry and
angle of sag, be subjected to greater loads than the impact load
imposed by an attached component. When the angle of horizontal
lifeline sag is less than 30 degrees, the impact force imparted
to the lifeline by an attached lanyard is greatly amplified. For
example, with a sag angle of 15 degrees, the force amplification
is about 2:1 and at 5 degrees sag, it is about 6:1. Depending
on the angle of sag, and the line's elasticity, the strength of
the horizontal lifeline and the anchorages to which it is attached
should be increased a number of times over that of the lanyard.
Extreme care should be taken in considering a horizontal lifeline
for multiple tie-offs. The reason for this is that in multiple
tie-offs to a horizontal lifeline, if one employee falls, the
movement of the falling employee and the horizontal lifeline during
arrest of the fall may cause other employees to also fall. Horizontal
lifeline and anchorage strength should be increased for each additional
employee to be tied-off. For these and other reasons, the design
of systems using horizontal lifelines must only be done by qualified
persons. Testing of installed lifelines and anchors prior to use
is recommended.
(g) The strength of an eye-bolt is rated along the axis of the
bolt and its strength is greatly reduced if the force is applied
at an angle to this axis (in the direction of shear). Also, care
should be exercised in selecting the proper diameter of the eye
to avoid accidental disengagement of snap-hooks not designed to
be compatible for the connection.
(h) Due to the significant reduction in the strength of the
lifeline/lanyard (in some cases, as much as a 70 percent reduction),
the sliding hitch knot should not be used for lifeline/lanyard
connections except in emergency situations where no other available
system is practical. The "one-and-one" sliding hitch
knot should never be used because it is unreliable in stopping
a fall. The "two-and-two," or "three-and-three"
knot (preferable), may be used in emergency situations; however,
care should be taken to limit free fall distance to a minimum
because of reduced lifeline/lanyard strength.
(9) Vertical lifeline considerations. As required by the standard,
each employee must have a separate lifeline when the lifeline
is vertical. The reason for this is that in multiple tie-offs
to a single lifeline, if one employee falls, the movement of the
lifeline during the arrest of the fall may pull other employees'
lanyards, causing them to fall as well.
(10) Snap-hook considerations.
(a) Required by this standard for all connections, locking snap-hooks
incorporate a positive locking mechanism in addition to the spring
loaded keeper, which will not allow the keeper to open under moderate
pressure without someone first releasing the mechanism. Such a
feature, properly designed, effectively prevents roll-out from
occurring.
(b) As required by the standard WAC 296-24-88050 (5)(a) the
following connections must be avoided (unless properly designed
locking snap-hooks are used) because they are conditions which
can result in roll-out when a nonlocking snap-hook is used:
? Direct connection of a snap-hook to a horizontal lifeline.
? Two (or more) snap-hooks connected to one dee-ring.
? Two snap-hooks connected to each other.
? A snap-hook connected back on its integral lanyard.
? A snap-hook connected to a webbing loop or webbing lanyard.
? Improper dimensions of the dee-ring, rebar, or other connection
point in relation to the snap-hook dimensions which would allow
the snap-hook keeper to be depressed by a turning motion of the
snap-hook.
(11) Free fall considerations. The employer and employee should
at all times be aware that a system's maximum arresting force
is evaluated under normal use conditions established by the manufacturer,
and in no case using a free fall distance in excess of 6 feet
(1.8 m). A few extra feet of free fall can significantly increase
the arresting force on the employee, possibly to the point of
causing injury. Because of this, the free fall distance should
be kept at a minimum, and, as required by the standard, in no
case greater than 6 feet (1.8 m). To help assure this, the tie-off
attachment point to the lifeline or anchor should be located at
or above the connection point of the fall arrest equipment to
harness. (Since otherwise additional free fall distance is added
to the length of the connecting means (i.e. lanyard).) Attaching
to the working surface will often result in a free fall greater
than 6 feet (1.8 m). For instance, if a 6 foot (1.8 m) lanyard
is used, the total free fall distance will be the distance from
the working level to the body harness attachment point plus the
6 feet (1.8 m) of lanyard length. Another important consideration
is that the arresting force which the fall system must withstand
also goes up with greater distances of free fall, possibly exceeding
the strength of the system.
(12) Elongation and deceleration distance considerations. Other
factors involved in a proper tie-off are elongation and deceleration
distance. During the arresting of a fall, a lanyard will experience
a length of stretching or elongation, whereas activation of a
deceleration device will result in a certain stopping distance.
These distances should be available with the lanyard or device's
instructions and must be added to the free fall distance to arrive
at the total fall distance before an employee is fully stopped.
The additional stopping distance may be very significant if the
lanyard or deceleration device is attached near or at the end
of a long lifeline, which may itself add considerable distance
due to its own elongation. As required by the standard, sufficient
distance to allow for all of these factors must also be maintained
between the employee and obstructions below, to prevent an injury
due to impact before the system fully arrests the fall. In addition,
a minimum of 12 feet (3.7 m) of lifeline should be allowed below
the securing point of a rope grab type deceleration device, and
the end terminated to prevent the device from sliding off the
lifeline. Alternatively, the lifeline should extend to the ground
or the next working level below. These measures are suggested
to prevent the worker from inadvertently moving past the end of
the lifeline and having the rope grab become disengaged from the
lifeline.
(13) Obstruction considerations. The location of the tie-off
should also consider the hazard of obstructions in the potential
fall path of the employee. Tie-offs which minimize the possibilities
of exaggerated swinging should be considered.
(14) Other considerations. Because of the design of some personal
fall arrest systems, additional considerations may be required
for proper tie-off. For example, heavy deceleration devices of
the self-retracting type should be secured overhead in order to
avoid the weight of the device having to be supported by the employee.
Also, if self-retracting equipment is connected to a horizontal
lifeline, the sag in the lifeline should be minimized to prevent
the device from sliding down the lifeline to a position which
creates a swing hazard during fall arrest. In all cases, manufacturer's
instructions should be followed.
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