- Standard
Number: 1910.66AppC
- Standard
Title: Personal Fall Arrest System (Section I - Mandatory;
Sections II and III - Non-Mandatory)
- SubPart
Number: F
- SubPart
Title: Powered Platforms, Manlifts, and Vehicle-Mounted
Work Platforms
Use of the Appendix
Section I of appendix
C sets out the mandatory criteria for personal fall arrest systems
used by all employees using powered platforms, as required by
paragraph (j)(1) of this standard. Section II sets out nonmandatory
test procedures which may be used to determine compliance with
applicable requirements contained in section I of this appendix.
Section III provides nonmandatory guidelines which are intended
to assist employers in complying with these provisions.
I. "Personal
fall arrest systems" - (a) "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 paragraph
1910.66(j).
(b) "Definitions."
"Anchorage"
means a secure point of attachment for lifelines, lanyards
or deceleration devices, and which is independent of the means
of supporting or suspending the employee.
"Body belt"
means a strap with means both for securing it about the waist
and for attaching it to a lanyard. lifeline, or deceleration
device.
"Body harness"
means a design of straps which may be secured about the employee
in a manner to distribute the fall arrest forces over at least
the thighs, pelvis. waist, chest and shoulders with means
for attaching it,to other components of a personal fall arrest
system.
"Buckle"
means any device for holding the body belt or body harness
closed around the employee's body.
"Competent
person" means a person who is capable of identifying
hazardous or dangerous conditions in the personal fall arrest
system or any component thereof, as well as in their application
and use with related equipment.
"Connector"
means a device which is used to couple (connect) parts of
the system together. It may be an independent component of
the system (such as a carabiner), or 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 lanyard,
or automatic self retracting-lifeline/lanyard, which serves
to dissipate a substantial amount of energy during a fall
arrest, or otherwise limits 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 body belt or 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 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 the 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 belt or 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, lifeline and lanyard elongation but
include any deceleration device slide distance or self-retracting
lifeline/lanyard extension before they operate and fall arrest
forces occur.
"Lanyard"
means a flexible line of rope, wire rope, or strap which is
used to secure the body belt or body harness to a deceleration
device, lifeline, or anchorage.
"Lifeline"
means a component consisting of a flexible line for connection
to an anchorage at one end to hang vertically (vertical lifeline),
or for connection to anchorages at both ends to stretch horizontally
(horizontal lifeline), and which serves as a means for connecting
other components of a personal fall arrest system to the anchorage.
"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, a body belt or body harness and may
include a lanyard, deceleration device, lifeline, or suitable
combinations of these.
"Qualified
person" means one with a recognized degree or professional
certificate and extensive knowledge and experience in the
subject field who is capable of design, analysis, evaluation
and specifications in the subject work, project, or product.
"Rope grab"
means a deceleration device which travels on a lifeline and
automatically frictionally engages the lifeline and locks
so as to arrest the fall of an employee. A rope grab usually
employs the principle of inertial locking, cam/lever locking,
or both.
"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 connector comprised of a hookshaped member with a
normally closed keeper, or similar arrangement, which may
be opened to permit the hook to receive an object and, when
released, automatically closes to retain the object. Snap-hooks
are generally one of two types:
- The locking
type with a self-closing, self-locking keeper which remains
closed and locked until unlocked and pressed open for connection
or disconnection, or
- The non-locking
type with a self-closing keeper which remains closed until
pressed open for connection or disconnection.
"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.
(c) Design for
system components. (1) Connectors shall be drop forged, pressed
or formed steel, or made of equivalent materials.
(2) Connectors
shall have a corrosion-resistant finish, and all surfaces and
edges shall be smooth to prevent damage to interfacing parts
of the system.
(3) Lanyards and
vertical lifelines which tie-off one employee shall have a minimum
breaking strength of 5,000 pounds (22.2 kN).
(4) Self-retracting
lifelines and lanyards which automatically limit free fall distance
to two feet (0.61 m) or less shall 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.
(5) Self-retracting
lifelines and lanyards which do not limit free fall distance
to two feet (0.61 m) or less, ripstitch lanyards, and tearing
and deforming lanyards shall be capable of sustaining a minimum
tensile load of 5,000 pounds (22.2 kN) applied to the device
with the lifeline or lanyard in the fully extended position.
(6) Dee-rings
and snap-hooks shall be capable of sustaining a minimum tensile
load of 5,000 pounds (22.2 kN).
(7) Dee-rings
and snap-hooks shall be 100 percent proof-tested to a minimum
tensile load of 3,600 pounds (16 kN) without cracking, breaking,
or taking permanent deformation.
(8) Snap-hooks
shall 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 shall be a locking type snap-hook designed and used
to prevent disengagement of the snap-hook by the contact of
the snaphook keeper by the connected member.
(9) Horizontal
lifelines, where used, shall be designed, and installed 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.
(10) Anchorages
to which personal fall arrest equipment is attached shall be
capable of supporting at least 5,000 pounds (22.2 kN) per employee
attached, or shall 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.
(11) Ropes and
straps (webbing) used in lanyards, lifelines, and strength components
of body belts and body harnesses, shall be made from synthetic
fibers or wire rope.
(d) "System
performance criteria." (1) Personal fall arrest systems
shall, when stopping a fall:
(i) Limit maximum
arresting force on an employee to 900 pounds (4 kN) when used
with a body belt;
(ii) Limit maximum
arresting force on an employee to 1,800 pounds (8 kN) when
used with a body harness;
(iii) Bring
an employee to a complete stop and limit maximum deceleration
distance an employee travels to 3.5 feet (1.07 m); and
(iv) Shall have
sufficient strength to withstand twice the potential impact
energy of an employee free falling a distance of six feet
(1.8 m), or the free fall distance permitted by the system,
whichever is less.
(2)(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 paragraphs (b),
(c) and (d) in section II of this appendix shall be considered
as complying with the provisions of paragraphs (d)(1)(i) through
(d)(1)(iv) above.
(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 paragraphs (b), (c) and
(d) in section II may be considered as complying with the provisions
of paragraphs (d)(1)(i) through (d)(1)(iv) provided that the
criteria and protocols are modified appropriately to provide
proper protection for such heavier weights.
(e) "Care
and use." (1) Snap-hooks, unless of a locking type designed
and used to prevent disengagement from the following connections,
shall 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.
(2) Devices used
to connect to a horizontal lifeline which may become a vertical
lifeline shall be capable of locking in either direction on
the lifeline.
(3) Personal fall
arrest systems shall be rigged such that an employee can neither
free fall more than six feet (1.8 m), nor contact any lower
level.
(4) The attachment
point of the body belt shall be located in the center of the
wearer's back. The attachment point of the body harness shall
be located in the center of the wearer's back near shoulder
level, or above the wearer's head.
(5) When vertical
lifelines are used, each employee shall be provided with a separate
lifeline.
(6) Personal fall
arrest systems or components shall be used only for employee
fall protection.
(7) Personal fall
arrest systems or components subjected to impact loading shall
be immediately removed from service and shall not be used again
for employee protection unless inspected and determined by a
competent person to be undamaged and suitable for reuse.
(8) The employer
shall provide for prompt rescue of employees in the event of
a fall or shall assure the self-rescue capability of employees.
(9) Before using
a personal fall arrest system and after any component or system
is changed, employees shall be trained in accordance with the
requirements of paragraph 1910.66(i)(1), in the safe use of
the system.
(f) "Inspections."
Personal fall arrest systems shall be inspected prior to each
use for mildew, wear, damage and other deterioration, and defective
components shall be removed from service if their strength or
function may be adversely affected.
II. "Test
methods for personal fall arrest systems (non-mandatory)"
- (a) "General." Paragraphs (b), (c), (d) and (e),
of this section II set forth test procedures which may be used
to determine compliance with the requirements in paragraph (d)(1)(i)
through (d)(1)(iv) of section I of this appendix.
(b) "General
conditions for all tests in section II." (1) Lifelines,
lanyards and deceleration devices should be attached to an anchorage
and connected to the body-belt or body harness in the same manner
as they would be when used to protect employees.
(2) 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.
(3) The frequency
response of the load measuring instrumentation should be 120
Hz.
(4) 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 four inches (96 cm plus or minus 10 cm).
(5) 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.
(6) 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.
(7) The system's
performance should be evaluated taking into account the range
of environmental conditions for which it is designed to be used.
(8) Following
the test, the system need not be capable of further operation.
(c) "Strength
test." (1) During the testing of all systems a test weight
of 300 pounds plus or minus five pounds (135 kg plus or minus
2.5 kg) should be used. (See paragraph (b)(4), above.)
(2) The test consists
of dropping the test weight once. A new unused system should
be used for each test.
(3) For lanyard
systems, the lanyard length should be six feet plus or minus
two 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.
(4) 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 two feet (0.61 m).
(5) For lanyard
systems, for systems with deceleration devices which do not
automatically limit free fall distance to two 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 belt or 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 (six 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 non-elastic wire
lanyard of sufficient length may need to be added to the system
(for test purposes) to create the necessary free fall distance.
(6) For deceleration
device systems with integral lifelines or lanyards which automatically
limit free fall distance to two feet (0.61 m) or less, the test
weight should be rigged to free fall a distance of four feet
(1.22 m).
(7) Any weight
which detaches from the belt or harness should constitute failure
for the strength test.
(d) "Force
test" - (1) "General." The test consists of dropping
the respective test weight specified in (d)(2)(i) or (d)(3)(i)
once. A new, unused system should be used for each test.
(2) "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 paragraph (b)(4), above.)
(ii) Lanyard length
should be six feet plus or minus two 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.
(iii) The test
weight should fall free from the anchorage level to its hanging
location (a total of six feet (1.83 m) free fall distance) without
interference, obstruction, or hitting the floor or ground during
the test.
(3) "For
all other 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 paragraph (b)(4), 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 six 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 belt or harness).
(B) For deceleration
device systems with integral lifelines or lanyards which automatically
limit free fall distance to two 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).
(4) A system fails
the force test if the recorded maximum arresting force exceeds
1,260 pounds (15.6 kN) when using a body belt, and/or exceeds
2,520 pounds (11.2 kN) when using a body harness.
(5) The maximum
elongation and deceleration distance should be recorded during
the force test.
(e) "Deceleration
device tests" - (1) "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.
(2) "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.
(3) "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.
III. "Additional
non-mandatory guidelines for personal full arrest systems."
The following information constitutes additional guidelines
for use in complying with requirements for a personal fall arrest
system.
(a) "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.
(b) "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. Section 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.
(c) "Comment
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, body belts 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 belt (or 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.
(d) "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.
(e) "Instruction
considerations." Employers should obtain comprehensive
instructions from the supplier as to the system's proper use
and application, including, where applicable:
(1) The force
measured during the sample force test;
(2) The maximum
elongation measured for lanyards during the force test;
(3) The deceleration
distance measured for deceleration devices during the force
test;
(4) Caution statements
on critical use limitations;
(5) Application
limits;
(6) Proper hook-op,
anchoring and tie-off techniques, including the proper dee-ring
or other attachment point to use on the body belt and harness
for fall arrest;
(7) Proper climbing
techniques;
(8) Methods of
inspection, use, cleaning, and storage; and
(9) Specific lifelines
which may be used. This information should be provided to employees
during training.
(f) "Inspection
considerations." As stated in the standard (section I,
Paragraph (f)), 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; non-functioning
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.
(g) "Rescue
considerations." As required by the standard (section I
Paragraph (e)(8)), 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.
(h) "Tie-off
considerations." (1) 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.
(2) 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.
(3) 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.
(4) 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.
(5) 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.
(6) 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.
(7) 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.
(8) 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.
(i) "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.
(j) "Snap-hook
considerations." Although not required by this standard
for all connections, locking snap-hooks designed for connection
to suitable objects (of sufficient strength) are highly recommended
in lieu of the non-locking type. 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.
As required by
the standard (section I, paragraph (e)(1)) 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 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.
(k) "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 six 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 six 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 belt or 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 six feet (1.8 m). For instance,
if a six foot (1.8 m) lanyard is used, the total free fall distance
will be the distance from the working level to the body belt
(or harness) attachment point plus the six 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.
(l) "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.
(m) "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. In addition, when
a body belt is used, the employee's body will go through a horizontal
position to a jack-knifed position during the arrest of all
falls. Thus, obstructions which might interfere with this motion
should be avoided or a severe injury could occur.
(n) "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.
|
