1910.66—Powered platforms for building maintenance.
(a) Scope.
This section covers powered platform installations permanently dedicated to interior or exterior building maintenance of a specific structure or group of structures. This section does not apply to suspended scaffolds (swinging scaffolds) used to service buildings on a temporary basis and covered under subpart D of this part, nor to suspended scaffolds used for construction work and covered under subpart L of 29 CFR part 1926. Building maintenance includes, but is not limited to, such tasks as window cleaning, caulking, metal polishing and reglazing.
(b) Application—
(1) New installations.
This section applies to all permanent installations completed after July 23, 1990. Major modifications to existing installations completed after that date are also considered new installations under this section.
(2) Existing installations.
(i)
Permanent installations in existence and/or completed before July 23, 1990 shall comply with paragraphs (g), (h), (i), (j) and appendix C of this section.
(ii)
In addition, permanent installations completed after August 27, 1971, and in existence and/or completed before July 23, 1990, shall comply with appendix D of this section.
(c) Assurance.
(1)
Building owners of new installations shall inform the employer before each use in writing that the installation meets the requirements of paragraphs (e)(1) and (f)(1) of this section and the additional design criteria contained in other provisions of paragraphs (e) and (f) of this section relating to: required load sustaining capabilities of platforms, building components, hoisting and supporting equipment; stability factors for carriages, platforms and supporting equipment; maximum horizontal force for movement of carriages and davits; design of carriages, hoisting machines, wire rope and stabilization systems; and design criteria for electrical wiring and equipment.
(2)
Building owners shall base the information required in paragraph (c)(1) of this section on the results of a field test of the installation before being placed into service and following any major alteration to an existing installation, as required in paragraph (g)(1) of this section. The assurance shall also be based on all other relevant available information, including, but not limited to, test data, equipment specifications and verification by a registered professional engineer.
(3)
Building owners of all installations, new and existing, shall inform the employer in writing that the installation has been inspected, tested and maintained in compliance with the requirements of paragraphs (g) and (h) of this section and that all protection anchorages meet the requirements of paragraph (I)(c)(10) of appendix C.
(4)
The employer shall not permit employees to use the installation prior to receiving assurance from the building owner that the installation meets the requirements contained in paragraphs (c)(1) and (c)(3) of this section.
Anemometer means an instrument for measuring wind velocity.
Angulated roping means a suspension method where the upper point of suspension is inboard from the attachments on the suspended unit, thus causing the suspended unit to bear against the face of the building.
Building face roller means a rotating cylindrical member designed to ride on the face of the building wall to prevent the platform from abrading the face of the building and to assist in stabilizing the platform.
Building maintenance means operations such as window cleaning, caulking, metal polishing, reglazing, and general maintenance on building surfaces.
Cable means a conductor, or group of conductors, enclosed in a weatherproof sheath, that may be used to supply electrical power and/or control current for equipment or to provide voice communication circuits.
Carriage means a wheeled vehicle used for the horizontal movement and support of other equipment.
Certification means a written, signed and dated statement confirming the performance of a requirement of this section.
Combination cable means a cable having both steel structural members capable of supporting the platform, and copper or other electrical conductors insulated from each other and the structural members by nonconductive barriers.
Competent person means a person who, because of training and experience, is capable of identifying hazardous or dangerous conditions in powered platform installations and of training employees to identify such conditions.
Continuous pressure means the need for constant manual actuation for a control to function.
Control means a mechanism used to regulate or guide the operation of the equipment.
Davit means a device, used singly or in pairs, for suspending a powered platform from work, storage and rigging locations on the building being serviced. Unlike outriggers, a davit reacts its operating load into a single roof socket or carriage attachment.
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.
Ground rigging means a method of suspending a working platform starting from a safe surface to a point of suspension above the safe surface.
Ground rigged davit means a davit which cannot be used to raise a suspended working platform above the building face being serviced.
Guide button means a building face anchor designed to engage a guide track mounted on a platform.
Guide roller means a rotating cylindrical member, operating separately or as part of a guide assembly, designed to provide continuous engagement between the platform and the building guides or guideways.
Guide shoe means a device attached to the platform designed to provide a sliding contact between the platform and the building guides.
Hoisting machine means a device intended to raise and lower a suspended or supported unit.
Hoist rated load means the hoist manufacturer's maximum allowable operating load.
Installation means all the equipment and all affected parts of a building which are associated with the performance of building maintenance using powered platforms.
Interlock means a device designed to ensure that operations or motions occur in proper sequence.
Intermittent stabilization means a method of platform stabilization in which the angulated suspension wire rope(s) are secured to regularly spaced building anchors.
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.
Live load means the total static weight of workers, tools, parts, and supplies that the equipment is designed to support.
Obstruction detector means a control that will stop the suspended or supported unit in the direction of travel if an obstruction is encountered, and will allow the unit to move only in a direction away from the obstruction.
Operating control means a mechanism regulating or guiding the operation of equipment that ensures a specific operating mode.
Operating device means a device actuated manually to activate a control.
Outrigger means a device, used singly or in pairs, for suspending a working platform from work, storage, and rigging locations on the building being serviced. Unlike davits, an outrigger reacts its operating moment load as at least two opposing vertical components acting into two or more distinct roof points and/or attachments.
Platform rated load means the combined weight of workers, tools, equipment and other material which is permitted to be carried by the working platform at the installation, as stated on the load rating plate.
Poured socket means the method of providing wire rope terminations in which the ends of the rope are held in a tapered socket by means of poured spelter or resins.
Primary brake means a brake designed to be applied automatically whenever power to the prime mover is interrupted or discontinued.
Prime mover means the source of mechanical power for a machine.
Rated load means the manufacturer's recommended maximum load.
Rated strength means the strength of wire rope, as designated by its manufacturer or vendor, based on standard testing procedures or acceptable engineering design practices.
Rated working load means the combined static weight of men, materials, and suspended or supported equipment.
Registered professional engineer means a person who has been duly and currently registered and licensed by an authority within the United States or its territories to practice the profession of engineering.
Roof powered platform means a working platform where the hoist(s) used to raise or lower the platform is located on the roof.
Roof rigged davit means a davit used to raise the suspended working platform above the building face being serviced. This type of davit can also be used to raise a suspended working platform which has been ground-rigged.
Rope means the equipment used to suspend a component of an equipment installation, i.e., wire rope.
Safe surface means a horizontal surface intended to be occupied by personnel, which is so protected by a fall protection system that it can be reasonably assured that said occupants will be protected against falls.
Secondary brake means a brake designed to arrest the descent of the suspended or supported equipment in the event of an overspeed condition.
Self powered platform means a working platform where the hoist(s) used to raise or lower the platform is mounted on the platform.
Speed reducer means a positive type speed reducing machine.
Stability factor means the ratio of the stabilizing moment to the overturning moment.
Stabilizer tie means a flexible line connecting the building anchor and the suspension wire rope supporting the platform.
Supported equipment means building maintenance equipment that is held or moved to its working position by means of attachment directly to the building or extensions of the building being maintained.
Suspended equipment means building maintenance equipment that is suspended and raised or lowered to its working position by means of ropes or combination cables attached to some anchorage above the equipment.
Suspended scaffold (swinging scaffold) means a scaffold supported on wire or other ropes, used for work on, or for providing access to, vertical sides of structures on a temporary basis. Such scaffold is not designed for use on a specific structure or group of structures.
Tail line means the nonsupporting end of the wire rope used to suspend the platform.
Tie-in guides means the portion of a building that provides continuous positive engagement between the building and a suspended or supported unit during its vertical travel on the face of the building.
Traction hoist means a type of hoisting machine that does not accumulate the suspension wire rope on the hoisting drum or sheave, and is designed to raise and lower a suspended load by the application of friction forces between the suspension wire rope and the drum or sheave.
Transportable outriggers means outriggers designed to be moved from one work location to another.
Trolley carriage means a carriage suspended from an overhead track structure.
Verified means accepted by design, evaluation, or inspection by a registered professional engineer.
Weatherproof means so constructed that exposure to adverse weather conditions will not affect or interfere with the proper use or functions of the equipment or component.
Winding drum hoist means a type of hoisting machine that accumulates the suspension wire rope on the hoisting drum.
Working platform means suspended or supported equipment intended to provide access to the face of a building and manned by persons engaged in building maintenance.
Wrap means one complete turn of the suspension wire rope around the surface of a hoist drum.
(e) Powered platform installations—Affected parts of buildings—
(1) General requirements.
The following requirements apply to affected parts of buildings which utilize working platforms for building maintenance.
(i)
Structural supports, tie-downs, tie-in guides, anchoring devices and any affected parts of the building included in the installation shall be designed by or under the direction of a registered professional engineer experienced in such design;
(iii)
The building installation shall provide safe access to, and egress from, the equipment and sufficient space to conduct necessary maintenance of the equipment;
(iv)
The affected parts of the building shall have the capability of sustaining all the loads imposed by the equipment; and,
(v)
The affected parts of the building shall be designed so as to allow the equipment to be used without exposing employees to a hazardous condition.
(2) Tie-in guides.
(i)
The exterior of each building shall be provided with tie-in guides unless the conditions in paragraph (e)(2)(ii) or (e)(2)(iii) of this section are met.
Code of Federal Regulations
(ii)
If angulated roping is employed, tie-in guides required in paragraph (e)(2)(i) of this section may be eliminated for not more than 75 feet (22.9 m) of the uppermost elevation of the building, if infeasible due to exterior building design, provided an angulation force of at least 10 pounds (44.4 n) is maintained under all conditions of loading.
(iii)
Tie-in guides required in paragraph (e)(2)(i) of this section may be eliminated if one of the guide systems in paragraph (e)(2)(iii)(A), (e)(2)(iii)(B) or (e)(2)(iii)(C) of this section is provided, or an equivalent.
(A)
Intermittent stabilization system. The system shall keep the equipment in continuous contact with the building facade, and shall prevent sudden horizontal movement of the platform. The system may be used together with continuous positive building guide systems using tie-in guides on the same building, provided the requirements for each system are met.
(1) The maximum vertical interval between building anchors shall be three floors or 50 feet (15.3 m), whichever is less.
(2) Building anchors shall be located vertically so that attachment of the stabilizer ties will not cause the platform suspension ropes to angulate the platform horizontally across the face of the building. The anchors shall be positioned horizontally on the building face so as to be symmetrical about the platform suspension ropes.
(3) Building anchors shall be easily visible to employees and shall allow a stabilizer tie attachment for each of the platform suspension ropes at each vertical interval. If more than two suspension ropes are used on a platform, only the two building-side suspension ropes at the platform ends shall require a stabilizer attachment.
(4) Building anchors which extend beyond the face of the building shall be free of sharp edges or points. Where cables, suspension wire ropes and lifelines may be in contact with the building face, external building anchors shall not interfere with their handling or operation.
(5) The intermittent stabilization system building anchors and components shall be capable of sustaining without failure at least four times the maximum anticipated load applied or transmitted to the components and anchors. The minimum design wind load for each anchor shall be 300 (1334 n) pounds, if two anchors share the wind load.
(6) The building anchors and stabilizer ties shall be capable of sustaining anticipated horizontal and vertical loads from winds specified for roof storage design which may act on the platform and wire ropes if the platform is stranded on a building face. If the building anchors have different spacing than the suspension wire rope or if the building requires different suspension spacings on one platform, one building anchor and stabilizer tie shall be capable of sustaining the wind loads.
Code of Federal Regulations
(1) Guide buttons shall be coordinated with platform mounted equipment of paragraph (f)(5)(vi) of this section.
(2) Guide buttons shall be located horizontally on the building face so as to allow engagement of each of the guide tracks mounted on the platform.
(3) Guide buttons shall be located in vertical rows on the building face for proper engagement of the guide tracks mounted on the platform.
(4) Two guide buttons shall engage each guide track at all times except for the initial engagement.
(5) Guide buttons which extend beyond the face of the building shall be free of sharp edges or points. Where cables, ropes and lifelines may be in contact with the building face, guide buttons shall not interfere with their handling or operation.
(6) Guide buttons, connections and seals shall be capable of sustaining without damage at least the weight of the platform, or provision shall be made in the guide tracks or guide track connectors to prevent the platform and its attachments from transmitting the weight of the platform to the guide buttons, connections and seals. In either case, the minimum design load shall be 300 pounds (1334 n) per building anchor.
Code of Federal Regulations
Code of Federal Regulations
(C)
System utilizing angulated roping and building face rollers. The system shall keep the equipment in continuous contact with the building facade, and shall prevent sudden horizontal movement of the platform. This system is acceptable only where the suspended portion of the equipment in use does not exceed 130 feet (39.6 m) above a safe surface or ground level, and where the platform maintains no less than 10 pounds (44.4 n) angulation force on the building facade.
(iv)
Tie-in guides for building interiors (atriums) may be eliminated when a registered professional engineer determines that an alternative stabilization system, including systems in paragraphs (e)(2)(iii) (A), (B) and (C), or a platform tie-off at each work station will provide equivalent safety.
(3) Roof guarding.
(i)
Employees working on roofs while performing building maintenance shall be protected by a perimeter guarding system which meets the requirements of paragraph (c)(1) of § 1910.23 of this part.
(ii)
The perimeter guard shall not be more than six inches (152 mm) inboard of the inside face of a barrier, i.e. the parapet wall, or roof edge curb of the building being serviced; however, the perimeter guard location shall not exceed an 18 inch (457 mm) setback from the exterior building face.
(4) Equipment stops.
Operational areas for trackless type equipment shall be provided with structural stops, such as curbs, to prevent equipment from traveling outside its intended travel areas and to prevent a crushing or shearing hazard.
(5) Maintenance access.
Means shall be provided to traverse all carriages and their suspended equipment to a safe area for maintenance and storage.
(6) Elevated track.
(i)
An elevated track system which is located four feet (1.2 m) or more above a safe surface, and traversed by carriage supported equipment, shall be provided with a walkway and guardrail system; or
(ii)
The working platform shall be capable of being lowered, as part of its normal operation, to the lower safe surface for access and egress of the personnel and shall be provided with a safe means of access and egress to the lower safe surface.
(7) Tie-down anchors.
Imbedded tie-down anchors, fasteners, and affected structures shall be resistant to corrosion.
(8) Cable stabilization.
(i)
Hanging lifelines and all cables not in tension shall be stabilized at each 200 foot (61 m) interval of vertical travel of the working platform beyond an initial 200 foot (61 m) distance.
(ii)
Hanging cables, other than suspended wire ropes, which are in constant tension shall be stabilized when the vertical travel exceeds an initial 600 foot (183 m) distance, and at further intervals of 600 feet (183 m) or less.
(9) Emergency planning.
A written emergency action plan shall be developed and implemented for each kind of working platform operation. This plan shall explain the emergency procedures which are to be followed in the event of a power failure, equipment failure or other emergencies which may be encountered. The plan shall also explain that employees inform themselves about the building emergency escape routes, procedures and alarm systems before operating a platform. Upon initial assignment and whenever the plan is changed the employer shall review with each employee those parts of the plan which the employee must know to protect himself or herself in the event of an emergency.
(10) Building maintenance.
Repairs or major maintenance of those building portions that provide primary support for the suspended equipment shall not affect the capability of the building to meet the requirements of this standard.
(11) Electrical requirements.
The following electrical requirements apply to buildings which utilize working platforms for building maintenance.
(i)
General building electrical installations shall comply with §§ 1910.302 through 1910.308 of this part, unless otherwise specified in this section;
(ii)
Building electrical wiring shall be of such capacity that when full load is applied to the equipment power circuit not more than a five percent drop from building service-vault voltage shall occur at any power circuit outlet used by equipment regulated by this section;
(iii)
The equipment power circuit shall be an independent electrical circuit that shall remain separate from all other equipment within or on the building, other than power circuits used for hand tools that will be used in conjunction with the equipment. If the building is provided with an emergency power system, the equipment power circuit may also be connected to this system;
(iv)
The power circuit shall be provided with a disconnect switch that can be locked in the “OFF” and “ON” positions. The switch shall be conveniently located with respect to the primary operating area of the equipment to allow the operators of the equipment access to the switch;
(v)
The disconnect switch for the power circuit shall be locked in the “ON” position when the equipment is in use; and
(vi)
An effective two-way voice communication system shall be provided between the equipment operators and persons stationed within the building being serviced. The communications facility shall be operable and shall be manned at all times by persons stationed within the building whenever the platform is being used.
(f) Powered platform installations—Equipment—
(1) General requirements.
The following requirements apply to equipment which are part of a powered platform installation, such as platforms, stabilizing components, carriages, outriggers, davits, hoisting machines, wire ropes and electrical components.
(i)
Equipment installations shall be designed by or under the direction of a registered professional engineer experienced in such design;
(ii)
The design shall provide for a minimum live load of 250 pounds (113.6 kg) for each occupant of a suspended or supported platform;
(iii)
Equipment that is exposed to wind when not in service shall be designed to withstand forces generated by winds of at least 100 miles per hour (44.7 m/s) at 30 feet (9.2 m) above grade; and
(iv)
Equipment that is exposed to wind when in service shall be designed to withstand forces generated by winds of at least 50 miles per hour (22.4 m/s) for all elevations.
(2) Construction requirements.
Bolted connections shall be self-locking or shall otherwise be secured to prevent loss of the connections by vibration.
(3) Suspension methods.
Elevated building maintenance equipment shall be suspended by a carriage, outriggers, davits or an equivalent method.
(i) Carriages.
Carriages used for suspension of elevated building maintenance equipment shall comply with the following:
(A)
The horizontal movement of a carriage shall be controlled so as to ensure its safe movement and allow accurate positioning of the platform for vertical travel or storage;
(C)
The initiation of a traversing movement for a manually propelled carriage on a smooth level surface shall not require a person to exert a horizontal force greater than 40 pounds (444.8 n);
(D)
Structural stops and curbs shall be provided to prevent the traversing of the carriage beyond its designed limits of travel;
(E)
Traversing controls for a powered carriage shall be of a continuous pressure weatherproof type. Multiple controls when provided shall be arranged to permit operation from only one control station at a time. An emergency stop device shall be provided on each end of a powered carriage for interrupting power to the carriage drive motors;
(F)
The operating controls(s) shall be so connected that in the case of suspended equipment, traversing of a carriage is not possible until the suspended portion of the equipment is located at its uppermost designed position for traversing; and is free of contact with the face of the building or building guides. In addition, all protective devices and interlocks are to be in the proper position to allow traversing of the carriage;
(G)
Stability for underfoot supported carriages shall be obtained by gravity, by an attachment to a structural support, or by a combination of gravity and a structural support. The use of flowing counterweights to achieve stability is prohibited.
(1) The stability factor against overturning shall not be less than two for horizontal traversing of the carriage, including the effects of impact and wind.
(2) The carriages and their anchorages shall be capable of resisting accidental over-tensioning of the wire ropes suspending the working platform, and this calculated value shall include the effect of one and one-half times the stall capacity of the hoist motor. All parts of the installation shall be capable of withstanding without damage to any part of the installation the forces resulting from the stall load of the hoist and one half the wind load.
(3) Roof carriages which rely on having tie-down devices secured to the building to develop the required stability against overturning shall be provided with an interlock which will prevent vertical platform movement unless the tie-down is engaged;
(H)
An automatically applied braking or locking system, or equivalent, shall be provided that will prevent unintentional traversing of power traversed or power assisted carriages;
(I)
A manual or automatic braking or locking system or equivalent, shall be provided that will prevent unintentional traversing of manually propelled carriages;
(K)
Safe access to and egress from the carriage shall be provided from a safe surface. If the carriage traverses an elevated area, any operating area on the carriage shall be protected by a guardrail system in compliance with the provisions of paragraph (f)(5)(i)(F) of this section. Any access gate shall be self-closing and self-latching, or provided with an interlock;
(L)
Each carriage work station position shall be identified by location markings and/or position indicators; and
(M)
The motors shall stall if the load on the hoist motors is at any time in excess of three times that necessary for lifting the working platform with its rated load.
(ii) Transportable outriggers.
(A)
Transportable outriggers may be used as a method of suspension for ground rigged working platforms where the point of suspension does not exceed 300 feet (91.5 m) above a safe surface. Tie-in guide system(s) shall be provided which meet the requirements of paragraph (e)(2) of this section.
(C)
Each transportable outrigger shall be secured with a tie-down to a verified anchorage on the building during the entire period of its use. The anchorage shall be designed to have a stability factor of not less than four against overturning or upsetting of the outrigger.
(D)
Access to and egress from the working platform shall be from and to a safe surface below the point of suspension.
(E)
Each transportable outrigger shall be designed for lateral stability to prevent roll-over in the event an accidental lateral load is applied to the outrigger. The accidental lateral load to be considered in this design shall be not less than 70 percent of the rated load of the hoist.
(F)
Each transportable outrigger shall be designed to support an ultimate load of not less than four times the rated load of the hoist.
(G)
Each transportable outrigger shall be so located that the suspension wire ropes for two point suspended working platforms are hung parallel.
(H)
A transportable outrigger shall be tied-back to a verified anchorage on the building with a rope equivalent in strength to the suspension rope.
(iii)
Davits. (A) Every davit installation, fixed or transportable, rotatable or non-rotatable shall be designed and installed to insure that it has a stability factor against overturning of not less than four.
(1) Access to and egress from the working platform shall be from a safe surface. Access or egress shall not require persons to climb over a building's parapet or guard railing; and
(2) The working platform shall be provided with wheels, casters or a carriage for traversing horizontally.
(1) The point of suspension shall not exceed 300 feet (91.5 m) above a safe surface. Guide system(s) shall be provided which meet the requirements of paragraph (e)(2) of this section;
(2) Access and egress to and from the working platform shall only be from a safe surface below the point of suspension.
(D)
A rotating davit shall not require a horizontal force in excess of 40 pounds (177.9 n) per person to initiate a rotating movement.
(1) A davit or part of a davit weighing more than 80 pounds (36 kg) shall be provided with a means for its transport, which shall keep the center of gravity of the davit at or below 36 inches (914 mm) above the safe surface during transport;
(2) A davit shall be provided with a pivoting socket or with a base that will allow the insertion or removal of a davit at a position of not more than 35 degrees above the horizontal, with the complete davit inboard of the building face being serviced; and
(3) Means shall be provided to lock the davit to its socket or base before it is used to suspend the platform.
(4) Hoisting machines.
(i)
Raising and lowering of suspended or supported equipment shall be performed only by a hoisting machine.
(v)
Each hoisting machine shall be capable of raising or lowering 125 percent of the rated load of the hoist.
(vi)
Moving parts of a hoisting machine shall be enclosed or guarded in compliance with paragraphs (a)(1) and (2) of § 1910.212 of this part.
(vii)
Winding drums, traction drums and sheaves and directional sheaves used in conjunction with hoisting machines shall be compatible with, and sized for, the wire rope used.
(viii)
Each winding drum shall be provided with a positive means of attaching the wire rope to the drum. The attachment shall be capable of developing at least four times the rated load of the hoist.
(ix)
Each hoisting machine shall be provided with a primary brake and at least one independent secondary brake, each capable of stopping and holding not less than 125 percent of the lifting capacity of the hoist.
(A)
The primary brake shall be directly connected to the drive train of the hoisting machine, and shall not be connected through belts, chains, clutches, or set screw type devices. The brake shall automatically set when power to the prime mover is interrupted.
(B)
(1) The secondary brake shall be an automatic emergency type of brake that, if actuated during each stopping cycle, shall not engage before the hoist is stopped by the primary brake.
(2) When a secondary brake is actuated, it shall stop and hold the platform within a vertical distance of 24 inches (609.6 mm).
(x)
Any component of a hoisting machine which requires lubrication for its protection and proper functioning shall be provided with a means for that lubrication to be applied.
(5) Suspended equipment—
(i) General requirements.
Each suspended unit component, except suspension ropes and guardrail systems, shall be capable of supporting, without failure, at least four times the maximum intended live load applied or transmitted to that component.
(B)
Each suspended unit component shall be constructed of materials that will withstand anticipated weather conditions.
(C)
Each suspended unit shall be provided with a load rating plate, conspicuously located, stating the unit weight and rated load of the suspended unit.
(D)
When the suspension points on a suspended unit are not at the unit ends, the unit shall be capable of remaining continuously stable under all conditions of use and position of the live load, and shall maintain at least a 1.5 to 1 stability factor against unit upset.
(E)
Guide rollers, guide shoes or building face rollers shall be provided, and shall compensate for variations in building dimensions and for minor horizontal out-of-level variations of each suspended unit.
(F)
Each working platform of a suspended unit shall be secured to the building facade by one or more of the following methods, or by an equivalent method:
(1) Continuous engagement to building anchors as provided in paragraph (e)(2)(i) of this section;
(2) Intermittent engagement to building anchors as provided in paragraph (e)(2)(iii)(A) of this section;
(3) Button guide engagement as provided in paragraph (e)(2)(iii)(B) of this section; or
(4) Angulated roping and building face rollers as provided in paragraph (e)(2)(iii)(C) of this section.
(G)
Each working platform of a suspended unit shall be provided with a guardrail system on all sides which shall meet the following requirements:
(1) The system shall consist of a top guardrail, midrail, and a toeboard;
(2) The top guardrail shall not be less than 36 inches (914 mm) high and shall be able to withstand at least a 100-pound (444 n) force in any downward or outward direction;
(3) The midrail shall be able to withstand at least a 75-pound (333 n) force in any downward or outward direction; and
(4) The areas between the guardrail and toeboard on the ends and outboard side, and the area between the midrail and toeboard on the inboard side, shall be closed with a material that is capable of withstanding a load of 100 pounds (45.4 KG.) applied horizontally over any area of one square foot (.09 m 2 ). The material shall have all openings small enough to reject passage of life lines and potential falling objects which may be hazardous to persons below.
(5) Toeboards shall be capable of withstanding, without failure, a force of at least 50 pounds (222 n) applied in any downward or horizontal direction at any point along the toeboard.
(6) Toeboards shall be three and one-half inches (9 cm) minimum in length from their top edge to the level of the platform floor.
(7) Toeboards shall be securely fastened in place at the outermost edge of the platform and have no more than one-half inch (1.3 cm) clearance above the platform floor.
(8) Toeboards shall be solid or with an opening not over one inch (2.5 cm) in the greatest dimension.
(ii) Two and four-point suspended working platforms.
(A)
The working platform shall be not less than 24 inches (610 mm) wide and shall be provided with a minimum of a 12 inch (305 mm) wide passage at or past any obstruction on the platform.
(B)
The flooring shall be of a slip-resistant type and shall contain no opening that would allow the passage of life lines, cables and other potential falling objects. If a larger opening is provided, it shall be protected by placing a material under the opening which shall prevent the passage of life lines, cables and potential falling objects.
(C)
The working platfrom shall be provided with a means of suspension that will restrict the platform's inboard to outboard roll about its longitudinal axis to a maximum of 15 degrees from a horizontal plane when moving the live load from the inboard to the outboard side of the platform.
(D)
Any cable suspended from above the platform shall be provided with a means for storage to prevent accumulation of the cable on the floor of the platform.
(E)
All operating controls for the vertical travel of the platform shall be of the continuous-pressure type, and shall be located on the platform.