PROPOSED RULES
LABOR AND INDUSTRIES
Original Notice.
Preproposal statement of inquiry was filed as WSR 05-17-104.
Title of Rule and Other Identifying Information: Chapter 296-870 WAC, Powered platforms.
Hearing Location(s): Department of Labor and Industries, Rooms S117 and S118, 7273 Linderson Way S.W., Tumwater, WA, on August 1, 2006, at 1:30 p.m.
Date of Intended Adoption: September 6, 2006.
Submit Written Comments to: Jim Hughes, Project Manager, P.O. Box 44620, Olympia, WA 98507-4620, e-mail HUGW235@LNI.WA.GOV, fax (360) 902-5619, by noon, August 11, 2006.
Assistance for Persons with Disabilities: Contact
Kimberly Johnson by noon, July 25, 2006, at (360) 902-5008, TTY (360) 902-4645.
Purpose of the Proposal and Its Anticipated Effects, Including Any Changes in Existing Rules: CR-101 Preproposal as filed for rules pertaining to elevating work platforms and powered platforms as WSR 05-17-104 as part of the department's long term goal to rewrite our safety and health rules.
Elevating work platforms rules were filed in a separate CR-102, WSR 06-09-069.
This CR-102 filing will create new chapter 296-870 WAC for powered platforms rules. Relevant sections of chapter 296-24 WAC, Part J-3, Powered platforms will be repealed with the elevating work platforms rules.
The rule makings will have the same effective date.
Reasons Supporting Proposal: The new rules will be easier for employers and employees to use and understand.
Statutory Authority for Adoption: RCW 49.17.010, 49.17.040, 149.17.050 [49.17.050], and 49.17.060.
Statute Being Implemented: Chapter 49.17 RCW.
Rule is not necessitated by federal law, federal or state court decision.
Name of Proponent: Department of labor and industries, governmental.
Name of Agency Personnel Responsible for Drafting: Tracy Spencer, Tumwater, Washington, (360) 902-5530; Implementation and Enforcement: Stephen M. Cant, Tumwater, Washington, (360) 902-5495.
No small business economic impact statement has been prepared under chapter 19.85 RCW. RCW 19.85.030 (1)(a) requires a small business economic impact statement (SBEIS) only when a rule will "impose more than a minor cost on businesses in an industry." An analysis of the proposed rule reveals that in addition to not imposing new costs on businesses, these revisions will make DOSH rules easier for employers and employees to understand and use, and thus save time and resources. Therefore, no SBEIS is required.
A cost-benefit analysis is not required under RCW 34.05.328. There are no costs to assess within these proposed rules. Therefore, no cost benefit analysis is required.
June 20, 2006
Gary Weeks
Director
OTS-8665.1
POWERED PLATFORMS
Building maintenance includes, but is not limited to,
tasks such as window cleaning, caulking, metal polishing, and
reglazing.
| Exemption: | This chapter does not apply to suspended scaffolds covered by a separate chapter, Scaffolds, chapter 296-874 WAC. |
A powered platform installation consists of all the equipment and the parts of the building involved with using the powered platform for building maintenance.
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Your responsibility:
To meet these requirements when using powered platforms.
Building owner certifications.
Personnel requirements.
Platform and hoist load limits.
Obstructions and slipping hazards.
Wind and adverse weather.
Corrosive substances.
Heat-producing processes.
Fall protection.
Communications.
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You must:
Obtain written certification from the building owner of any building with a powered platform installation that was completed or had major modification done after July 23, 1990, that the building and equipment meets the requirements of new installations-buildings, WAC 296-870-600 and new installations-equipment, WAC 296-870-700 of this chapter.
| Note: | The building owner needs to base the certification on: |
| The field test of the installation done before it is first placed into service or following any major modification to an existing installation; | |
| AND | |
| All other relevant available information, including but not limited to: | |
| Test data | |
| Equipment specifications | |
| Verification by a registered professional engineer. |
Obtain written certification from the building owner that the installation:
Has been inspected, tested, and maintained as required by inspection, testing, and maintenance, WAC 296-870-300 of this chapter;
AND
All fall protection anchorages meet the requirements of Appendix C -- Personal fall arrest system, WAC 296-24-88050, found in the General safety and health standards, chapter 296-24 WAC.
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You must:
Prohibit employees from using the installation until the building owner has provided the required written certifications.
Make sure working platforms are operated only by persons proficient in the operation, safe use and inspection of the particular working platform.
| References: | Building owner certification requirements are found in Building owner certifications, WAC 296-870-20005. |
| Training requirements for persons using platforms are found in Existing installations, WAC 296-870-400. |
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You must:
Make sure the load on the working platform does not exceed the rated load stated on the platform load rating plate.
Make sure hoists are not subjected to a load greater than one hundred twenty-five percent of their rated load.
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You must:
Prohibit the accumulation of tools, materials and debris on the platform that are not related to the work in progress.
Make sure stabilizer ties are:
Located to allow movement along the full length of the platform without interference;
AND
Long enough not to become entangled in rollers, hoists, or other machinery.
Prohibit employees from working on platforms covered with snow, ice, or other slippery material.
| Exemption: | Employees may be on platforms as necessary to remove the slipping hazard. |
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You must:
Prohibit using powered platforms in:
Winds exceeding twenty-five miles per hour (40.2 km/hr);
OR
Any other severe adverse weather conditions.
| Exemption: | Employees may use the platform during severe adverse weather conditions only to move it from an operating to a storage position. |
Have an anemometer mounted on the platform of an
exterior installation to provide on-site wind velocities
before and during use of the platform.
| Note: | Determine wind speed using the best available information, including on-site anemometer readings and local weather forecasts. |
| The anemometer may be a portable or hand held unit which is temporarily mounted during platform use. |
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You must:
Protect the platform, wire ropes, and lifelines from damage due to acids or other corrosive substances by using the precautions recommended by any of the following:
Corrosive substance producer or supplier
Platform manufacturer
Other equivalent information source.
Wash down platform members which have been exposed to acids or other corrosive substances with a neutralizing solution as recommended by the corrosive substance producer or supplier.
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You must:
Protect the platform members, wire ropes, and lifelines when using a heat-producing process.
Make sure wire ropes and lifelines which have been contacted by a heat-producing process are considered to be permanently damaged and not used.
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You must:
Protect employees on working platforms with a personal fall arrest system that meets the requirements of Appendix C -- Personal fall arrest system, WAC 296-24-88050, found in the General safety and health standards, chapter 296-24 WAC.
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You must:
Make sure the voice communication system between the equipment operators and persons stationed within the building is operable and manned whenever the platform is being used.
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Your responsibility:
To make sure powered platforms are inspected, tested, and maintained to keep them in safe operating condition.
Maintenance.
Initial installation and after major modification inspection and testing.
Before use inspections and tests.
Periodic inspections and tests.
Reshackling and resocketing wire ropes.
Disabling safety or electrical protective devices.
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You must:
Make sure all parts of the equipment that affect safe operation are maintained in proper working order so they are able to perform their intended functions. This includes, but is not limited to, all of the following:
Roof systems including roof track systems, tie-downs, or similar equipment
Building face guiding members including T-rails, indented mullions, or equivalent guides located in the face of a building
Brackets for cable stabilizers.
Take out of service any equipment that is not in proper working order.
Make sure the following parts are kept clean:
Control or power contacts and relays;
AND
All other parts whose proper function would be affected by dirt or other contaminants.
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You must:
Make sure a completed powered platform installation has been inspected and tested by the building owner:
Before it was first placed into service;
AND
Before it was returned to service after major modification was done.
Make sure the inspection and tests determined that:
All parts of the installation met the applicable requirements of this chapter;
AND
All safety and operating equipment functioned as required.
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You must:
Complete the inspections and tests contained in Table 1, Before Use Inspections and Tests, before allowing persons to use the platform.
Table 1
Before Use Inspections and Tests
| What: | When: | Inspection and test requirements: | |
| Working platforms and their components | | Before every use | Inspect for visible defects |
| and | |||
| | After each occurrence which might affect the platform's structural integrity | ||
| Suspension wire ropes | | Before every use | Visible inspection by a competent person for defects and gross damage |
| and | |||
| | After each occurrence which might affect the wire rope's integrity | ||
| Governors and secondary brakes | Before use each day | Test before use. If testing is not feasible, visually inspect the brake to make sure it is free to operate | |
| Hoists | Each day before lowering personnel below the top elevation of the building | Test in the lifting direction with the intended load to make sure it has sufficient capacity to raise personnel back to the boarding level | |
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You must:
Make sure the building owner has completed and documented the periodic inspections and tests shown in Table 2.
Make sure any documentation required by Table 2, Periodic Inspections and Tests, is readily available for your own review and that of the director or an authorized representative.
Make sure suspension wire rope is used and maintained as specified in the wire rope manufacturer's recommended procedures.
Remove from service a wire rope that has any of the following:
Broken wires exceeding three wires in one strand or six wires in one rope lay
Distortion of rope structure such as would result from crushing or kinking
Evidence of heat damage
Evidence of rope deterioration from corrosion
A broken wire within eighteen inches (460.8 mm) of the end attachments
Noticeable rusting and pitting
Evidence of core failure. This could be indicated by a lengthening of rope lay, protrusion of the rope core and a reduction in rope diameter
More than one valley break (broken wire)
Outer wire wear exceeds one-third of the original outer wire diameter
Any other condition which the competent person determines has significantly affected the integrity of the rope.
Table 2
Periodic Inspections and Tests
| What to inspect: | When to inspect: | Inspection and test requirements: | Building owner documentation: | |||
| Related building supporting structures | Intervals not exceeding twelve months | Inspection by a competent person | Keep a certification record of each inspection and test that includes all of the following: | |||
| | Date of the inspection | |||||
| | Signature of the person who performed the inspection | |||||
| | Number, or other identifier, of the building support structure and equipment which was inspected | |||||
| All parts of the equipment including control systems | Intervals specified by the manufacturer or supplier, but not to exceed twelve months | Inspection and test, where necessary, by a competent person to determine: | ||||
| | They are in safe operating condition | |||||
| and | ||||||
| | Parts subject to wear, such as wire ropes, bearings, gears, and governors have not worn to such an extent as to affect the safe operation of the installation | |||||
| Working platform | | Every thirty days | Maintenance inspection and test by a competent person following procedures recommended by the manufacturer | Keep a certification record of each inspection and test that includes all of the following: | ||
| or | | Date of the inspection and test | ||||
| | Before each work cycle if the work cycle is more than thirty days | | Signature of the person who performed the inspection and test | |||
| | An identifier for the platform installation which was inspected | |||||
| Governors and secondary brakes | Intervals specified by the manufacturer or supplier, but not to exceed twelve months | Inspection and test by a competent person. Results need to confirm: | ||||
| | The initiating device for the secondary braking system operates at the proper overspeed | |||||
| and | ||||||
| | The secondary brake is functioning properly | |||||
| If any hoisting machine or initiating device for the secondary brake system is removed from the equipment for testing, reinspect all reinstalled and directly related components before returning the equipment installation to service | ||||||
| Suspension wire ropes | | Once a month for ropes in service | A thorough inspection by a competent person | Keep a certification record of each monthly inspection that includes all of the following: | ||
| and | | Date of the inspection | ||||
| | Before they are returned to service for ropes that have been out of service for thirty days or more | | Signature of the person who performed the inspection | |||
| | Number, or other identifier, of the wire rope which was inspected | |||||
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You must:
Make sure the nondrum ends of hoisting wire ropes are reshackled or, if the rope uses poured socket fastenings, resocketed at intervals not exceeding twenty four months.
Make sure enough rope is cut from the end of the rope during reshackling or resocketing to remove any damaged or fatigued portions.
Make sure resocketed ropes meet the requirements of Suspension wire ropes and rope connections, WAC 296-870-70085.
Make sure limit switches affected by resocketed ropes are reset if necessary.
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You must:
Make sure no person renders any required safety devices or electrical protective devices inoperative unless necessary for tests, inspections, or maintenance.
Restore any disabled devices to normal operating condition immediately after the test, inspection or maintenance is completed.
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Your responsibility:
To train employees who operate or inspect powered platforms.
General training.
Emergency action plan.
Certification.
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You must:
Make sure employees are trained by a competent person.
Train employees who operate powered platforms in all of the following:
Recognizing safety hazards and the preventative measures to control or minimize hazards that are associated with:
&sqbul; Using powered platforms, including those that apply to the specific platform they will be operating;
AND
&sqbul; Their individual work tasks.
Emergency action plan procedures
Work procedures for operating, safely using and inspecting powered platforms.
Provide written work procedures for operating, safely using, and inspecting working platforms to be used in employee training.
| Note: | Visual presentations, such as graphics and pictures, may be used instead of written work procedures if it improves employee understanding. The powered platform system components manufacturers' operating manuals can serve as the basis for these work procedures. |
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You must:
Make sure a written emergency action plan is developed and implemented for each kind of working platform operation that contains at least both of the following:
An explanation of the emergency procedures to be followed in the event of any of the following situations:
&sqbul; Power failure
&sqbul; Equipment failure
&sqbul; Other emergencies which may be encountered.
That employees are informed about the building emergency escape routes, procedures and alarm systems.
Review with each employee those parts of the plan they need to know to protect themselves in the event of an emergency:
Upon initial assignment;
AND
Whenever the plan is changed.
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You must:
Certify in writing that employees have been trained in operating and inspecting a working platform.
Make sure training certifications are:
Prepared when the employee has completed training;
AND
Contain all of the following:
&sqbul; Name of the person trained
&sqbul; Signature of the person who conducted the training
&sqbul; Date training was completed.
Make sure the training certification is:
Maintained while the employee works for you;
AND
Kept readily available for review by the director or an authorized representative.
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IMPORTANT:
This section applies to permanent powered platform installations that meet all of the following:
The installation was completed between August 27, 1971, and July 24, 1990
There has been no major modification to the installation after July 23, 1990
The working platforms use electric-powered, winding
drum type hoisting machines.
| Note: | Platforms operated by other types of power and using other types of hoisting machines are allowed if they: |
| Have adequate protective devices for the type of power used; | |
| AND | |
| Provide reasonable safety for persons using or exposed to the equipment | |
| Other types of hoisting machines include, but are not limited to, machines such as traction drum hoisting machines, air powered machines, hydraulic powered machines, and internal combustion machines. |
An existing installation is a permanent powered platform installation that:
Was completed before July 23, 1990;
AND
Has had no major modification done after July 23, 1990.
Your responsibility:
To make sure powered platform installations completed between August 27, 1971, and July 24, 1990, meet these building and equipment requirements.
Design, construction, and installation.
Fall protection.
Electrical.
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You must:
Make sure powered platforms designated as Type F meet all the requirements in Part II of ANSI A120.1-1970, American National Standard Safety Requirements for Powered Platforms for Exterior Building Maintenance.
Definition:
A Type F powered platform has both of the following characteristics:
The working platform is suspended by at least four wire ropes and designed so that failure of any one wire rope will not substantially alter the normal position of the working platform
Only one layer of hoisting rope is permitted on the winding drums.
You must:
Make sure powered platforms designated as Type T meet all the requirements in Part III of ANSI A120.1-1970 American National Standard Safety Requirements for Powered Platforms for Exterior Building Maintenance except for section 28, Safety belts and lifelines.
Definition:
A Type T powered platform has a working platform that is suspended by at least two wire ropes. The platform will not fall to the ground if a wire rope fails, but the working platform's normal position would be upset.
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You must:
Make sure both Type F and Type T powered platforms meet the requirements of Appendix C -- Personal fall arrest system, WAC 296-24-88050, found in the General safety and health standards, chapter 296-24 WAC.
Make sure working platforms have permanent guardrails that meet all of the following requirements:
Guardrails on the building side (front) of the platform have a top rail that is not less that thirty-eight inches and not more than forty-five inches high.
Guardrails on the other three sides have a top rail that is not less than forty-five inches high.
Top rails are able to withstand a force of at least two hundred pounds
Guardrails have a midrail around the entire platform
between the top rail and the toeboard.
| Reference: | Ramps and walkways that are four feet (1.2 m) or more above a lower level need to have a guardrail system. These requirements are found in Working Surfaces, Guarding Floors and Wall Openings, Ladders, Part J-1, in the General safety and health standards, chapter 296-24 WAC. |
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You must:
Make sure electrical wiring and equipment meets the requirements of the National Electric Code, NFPA 70-1987, ANSI C1-1987, except as modified by ANSI A120.1-1970 American National Standard Safety Requirements for Powered Platforms for Exterior Building Maintenance.
Make sure runway conductor systems are:
Designed for use in exterior locations;
AND
Located to prevent contact with water or accumulated snow.
Make sure conductors, collectors, and disconnecting means meet the requirements for cranes and hoists in Article 610 of the National Electrical Code, NFPA 70-1987, ANSI C1-1987.
Make sure the power conductors are paralleled by a grounded conductor that meets both of the following:
It cannot be opened by the disconnecting means;
AND
The system is designed to not pose a hazard to persons in the area.
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IMPORTANT:
This section applies to permanent powered platform installations that meet either of the following:
Were completed after July 23, 1990;
OR
Have had major modifications done to an existing installation after July 23, 1990.
Definition:
A new installation is a permanent powered platform installation that was completed, or an existing installation that has had major modifications done, after July 23, 1990.
| Note: | If affected parts of the building meet the requirements of the edition of American National Standard Institute/American Society of Mechanical Engineers ANSI/ASME A120.1, Safety Requirements for Powered Platforms for Building Maintenance, that was in effect when the powered platform installation was completed, they will be considered to meet the requirements of this section. |
To make sure new powered platform installations meet these building requirements.
Design.
Stabilization systems.
Intermittent stabilization system.
Button guide stabilization system.
Stabilization system using angulated roping and building face rollers.
Cable stabilization.
Electrical.
Guarding roofs and other elevated areas.
Moving equipment.
Repair and maintenance.
Communications.
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You must:
Make sure structural supports, tie-downs, tie-in guides, anchoring devices and any affected parts of the building included in the installation are designed by, or under the direction of, a registered professional engineer experienced in such design.
Make sure affected parts of the building are capable of sustaining all the loads imposed by the equipment.
Make sure exterior installations are capable of withstanding prevailing climatic conditions.
Make sure the affected parts of the building allow employees to use the equipment without being exposed to a hazardous condition.
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You must:
Make sure the exterior of each building is provided with at least one of the following stabilization systems:
Continuous tie-in guides
Intermittent stabilization system
Button guide stabilization system
System using angulated roping and building face rollers
System equivalent to a continuous tie-in guide system
| Exemption: | Tie-in guides may be eliminated for not more than seventy-five feet (22.9 m) of the uppermost elevation of the building if: |
| Using tie-in guides there is not feasible due to building design; | |
| AND | |
| Angulated roping is used that provides a stabilizing force of at least ten pounds (44.4 n) under all conditions of loading. |
Make sure embedded tie-down anchors, fasteners, and affected structures are corrosion-resistant.
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| Note: | This system may be used with a continuous tie-in guide system on the same building as long as the requirements for each system are met. |
Make sure an intermittent stabilization system:
Keeps the equipment in constant contact with the building;
AND
Prevents sudden horizontal movement of the platform.
Make sure building anchors are located vertically so that:
The distance between anchors is not more than three floors or fifty feet (15.3 m), whichever is less;
AND
Attaching the suspension ropes to the stabilizer ties will not cause the platform to move horizontally across the face of the building.
Make sure the anchors are positioned horizontally on the building face so as to be symmetrical about the platform suspension ropes.
Make sure building anchors:
Are easily seen by employees;
AND
Allow a stabilizer tie attachment for each of the platform suspension ropes at each vertical interval.
Make sure building anchors that extend beyond the face of the building have no sharp edges or points.
Make sure building anchors do not interfere with the handling or operation of cables, suspension wire ropes and lifelines that may be in contact with the building face.
Make sure the building anchors and components can sustain, without failure, at least four times the maximum anticipated load applied or transmitted to them.
Make sure the building anchors and stabilizer ties can sustain the 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 the building face.
Make sure the minimum design wind load for each anchor is three hundred pounds (1334 n) if two anchors share the wind load.
Make sure one building anchor and stabilizer tie can sustain the wind load if either:
The building anchors have different spacing than the suspension wire rope;
OR
The building requires different suspension spacings on one platform.
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You must:
Make sure the guide buttons are:
Coordinated with the platform guide tracks and other platform-mounted equipment;
AND
Located on the building so they properly engage the guide tracks mounted on the platform.
Make sure two guide buttons engage each guide track at all times except for the initial engagement.
Make sure guide buttons that extend beyond the face of the building have no sharp edges or points.
Make sure guide buttons do not interfere with the handling or operation of cables, suspension wire ropes and lifelines that may be in contact with the building face.
Make sure guide buttons, connections, and seals are either:
Able to sustain, without damage, at least the weight of the platform;
OR
Are prevented by the guide tracks or guide track connectors from having the weight of the platform and its attachments transmitted to them.
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You must:
Make sure a stabilization system using angulated roping and building face rollers does all of the following:
Keeps the equipment in continuous contact with the building face
Prevents sudden horizontal movement of the platform
Maintains a stabilizing force of at least ten pounds (44.4 n) against the face of the building.
Make sure the suspended portion of the equipment is not used more than one hundred thirty feet (39.6 m) above a safe surface or ground level.
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You must:
Make sure hanging lifelines and all other cables not in tension are stabilized after the initial two hundred feet (61 m) of vertical travel of the working platform and every two hundred feet (61 m) thereafter.
Make sure hanging cables which are in constant tension, other than suspended wire ropes, are stabilized after an initial six hundred feet (183 m) of vertical travel of the working platform and at intervals of six hundred feet (183 m) or less thereafter.
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You must:
Make sure, when full load is applied to the equipment power circuit, that the building electrical wiring does not allow more than a five percent voltage drop from the building service vault voltage at any power circuit outlet used by the powered platform installation.
Make sure the equipment power circuit is provided with a disconnect switch that is all of the following:
Able to be locked in either the "off" or "on" position
Conveniently located with respect to the primary operating area of the equipment to allow equipment operators access to the switch
Locked in the "on" position when the equipment is being used.
Make sure the powered platform equipment power supply
is an independent electrical circuit that remains separate
from all other equipment within or on the building.
| Exemption: | The equipment power circuit may be connected to the electrical circuit supplying power to hand tools used in conjunction with the equipment. |
| Note: | If the building is provided with an emergency power system, the equipment power circuit may also be connected to the emergency power system. |
| Reference: | Unless otherwise specified in this section, building electrical installations have to meet the requirements of Electrical, Part L, in the General safety and health standards, chapter 296-24 WAC. |
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You must:
Make sure employees working on a roof or other elevated working area four feet (1.2 m) or more above an adjacent safe surface are protected by a perimeter guarding system.
| Reference: | Requirements for the perimeter guarding system are found in Guarding floor and wall openings and holes, WAC 296-24-750, found in the General safety and health standards, chapter 296-24 WAC. |
Make sure the inboard face of the perimeter guard is:
Not more than six inches (152 mm) inboard of the inside face of a barrier such as the parapet wall or roof edge curb;
AND
Not more than eighteen inches (457 mm) from the face of the building.
Make sure an elevated track system that is designed to be traversed by carriage-supported equipment and located four feet (1.2 m) or more above an adjacent safe surface is either:
Provided with a walkway and guardrail system;
OR
Has a working platform that can be lowered, as part of normal operations, to the lower safe surface.
Make sure personnel have a safe way to access and to egress from the lower safe surface.
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You must:
Make sure all carriages and carriage-supported equipment can be traversed to a safe area for storage and maintenance.
Make sure operational areas for trackless type equipment have structural stops, such as curbs, to prevent equipment from traveling outside its intended travel area.
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You must:
Make sure repair or major maintenance of parts of the building that provide primary support for suspended equipment does not affect the ability of the building to meet the requirements of this chapter.
[]
You must:
Make sure an effective two-way voice communication system is provided between the equipment operators and persons stationed within the building.
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IMPORTANT:
This section applies to permanent powered platform installations that meet either of the following:
Were completed after July 23, 1990;
OR
Have had major modifications done to an existing installation after July 23, 1990.
Definition:
A new installation is a permanent powered platform installation that was completed, or an existing installation that has had major modifications done, after July 23, 1990.
| Note: | If the powered platform equipment meets the requirements of the edition of American National Standard Institute/American Society of Mechanical Engineers ANSI/ASME A120.1, Safety Requirements for Powered Platforms for Building Maintenance, that was in effect when the powered platform installation was completed, it will be considered to meet the requirements of this section. |
To make sure equipment used with new powered platform installations meets these requirements.
Design and construction.
Carriages.
Carriage strength and stability.
Carriage traversing.
Transportable outriggers.
Davits.
Hoisting machines.
Suspended equipment strength and stability.
Suspended equipment guardrail system.
Suspended working platforms and manned platforms used on supported equipment.
Working platform fall protection.
Two- and four-point suspended working platforms.
Ground-rigged working platforms.
Intermittently stabilized working platforms.
Button guide stabilized working platforms.
Supported equipment.
Suspension wire ropes and rope connections.
Control circuits, power circuits and electrical protective devices.
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IMPORTANT:
This section applies to equipment which is part of a powered platform installation, such as platforms, stabilizing components, carriages, outriggers, davits, hoisting machines, wire ropes and electrical components.
You must:
Make sure equipment installations are designed by, or under the direction of, a registered professional engineer experienced in such design.
Make sure the design uses a minimum live load of two hundred fifty pounds (113.6 kg) for each occupant of a suspended or supported platform.
Make sure equipment exposed to wind when not in service is designed to withstand loads generated by winds of at least one hundred miles per hour (44.7 m/s) at thirty feet (9.2 m) above grade.
Make sure equipment exposed to wind when in service is designed to withstand loads generated by winds of at least fifty miles per hour (22.4 m/s) for all elevations.
Make sure elevated building maintenance equipment is suspended by one of the following:
A carriage
Outriggers
Davits
An equivalent method.
Make sure bolted connections are self-locking or otherwise secured to prevent loosening by vibration.
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You must:
Make sure each carriage work station is identified by location markings or position indicators.
Make sure means are provided to lock out the power supply for the carriage.
Make sure safe access to and egress from the carriage is provided from a safe surface.
Make sure any carriage access gate is either:
Self-closing and self-latching;
OR
Provided with an interlock.
Make sure any operating area on the carriage is protected by a guardrail system.
| Reference: | Guardrail system requirements are found in Suspended equipment guardrail system, WAC 296-870-70045. |
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You must:
Make sure roof carriage system stability is obtained by using gravity, attachment to a structural support, or a combination of gravity and structural attachment.
Never use a material that can flow as a counterweight to achieve stability.
Make sure the stability factor against overturning for horizontal traversing of the carriage, including wind and impact effects, is not less than two.
Make sure carriages and their anchorages can resist accidental over-tensioning of the wire ropes suspending the platform. Include in the calculation the effect of one and one-half times the stall load of the hoist.
Make sure all parts of the powered platform installation can withstand, without damage, the forces resulting from a load equal to the stall load of the hoist and one-half of the wind load.
Make sure roof carriages which develop the required stability against overturning by using tie-down devices secured to the building have an interlock which will prevent vertical platform movement unless the tie-down is engaged.
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You must:
Make sure carriages used to suspend powered platforms meet all of the following:
The horizontal movement of the carriage is controlled to permit it to be moved safely and to allow accurate positioning of the platform for vertical travel or storage
Structural stops and curbs are provided to prevent traversing of the carriage beyond its designed limits of travel
Powered carriages are limited to a maximum traversing speed of fifty feet per minute (0.3 m/s)
Manually propelled carriages on a smooth level surface require a horizontal force of not more than one hundred pounds (444.8 n) per person to initiate a traversing movement.
Make sure traversing controls for a powered carriage meet all of the following:
Controls are continuous pressure weatherproof type
Multiple controls, if provided, only permit operation from one control station at a time
An emergency stop device that interrupts power to the carriage drive motors is provided on each end of the carriage.
Make sure the operating controls of suspended equipment is connected so that traversing the carriage is not possible until:
The suspended portion of the equipment is at the uppermost designed position for traversing and free of contact with the face of the building or building guides;
AND
All protective devices and interlocks are in the proper position to allow traversing of the carriage.
Make sure unintentional traversing of the carriage is prevented by providing one of the following:
An automatically applied braking or locking system, or the equivalent, for power-traversed or power-assisted carriages
A manual or automatic braking or locking system, or the equivalent, for manually propelled carriages.
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You must:
Make sure transportable outriggers are only used when all of the following are met:
They are used with self-powered, ground-rigged working platforms
The point of suspension is not higher than three hundred feet (91.5 m) above a safe surface
A tie-in guide stabilization system is provided.
Make sure each outrigger is secured with a tie down to a verified anchorage on the building and meets all of the following:
The outrigger is tied down during the entire time it is used
The outrigger is tied back with a rope equivalent in strength to the suspension rope
The tie-back rope is installed parallel to the centerline of the outrigger
The anchorage has a design stability factor against overturning or upsetting of the outrigger of not less than four.
Make sure access to and egress from the working platform is from and to a safe surface below the point of suspension.
Make sure each outrigger has a design stability factor to prevent rollover in the event of an accidental lateral load on the outrigger of not less than seventy percent of the rated load of the hoist.
Make sure each outrigger is designed to support an ultimate load of not less than four times the rated load of the hoist.
Make sure each outrigger is located so that the suspension wire ropes for two point suspended working platforms are parallel.
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You must:
Make sure all davit installations are designed and installed to have a stability factor against overturning of not less than four.
Make sure access to and egress from the working platform of roof rigged davit systems:
Is from a safe surface;
AND
Does not require persons to climb over a building parapet or guardrail.
Make sure the working platform of a roof rigged davit system has wheels, casters, or a carriage for traversing horizontally.
Make sure ground rigged davit systems meet all of the following:
The point of suspension is not higher than three hundred feet (91.5 m) above a safe surface
A tie-in guide stabilization system is provided
Access to and egress from the working platform is from a safe surface below the point of suspension.
Make sure a rotating davit of a ground rigged davit system requires a horizontal force of forty pounds (177.9 n) or less per person to initiate a rotating movement.
Make sure a transportable davit or part of a davit weighing more than eighty pounds (36 kg) has means provided for its transport that keep the center of gravity of the davit at or below thirty-six inches (914 mm) above the safe surface during transport.
Make sure a transportable davit is provided with a pivoting socket or base that allows the davit to be removed or inserted:
At a position of not more than thirty-five degrees above the horizontal;
AND
With the complete davit inboard of the building face.
Make sure means are provided to lock a transportable davit to its socket or base before it is used to suspend the platform.
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You must:
Make sure suspended or supported equipment is raised or lowered only by a hoisting machine.
Make sure each hoisting machine is all of the following:
Powered only by air, electric, or hydraulic sources
Capable of raising or lowering one hundred twenty-five percent of the rated load of the hoist
Able to arrest any overspeed descent of the load.
Make sure the stall load of any hoist motor is not more than three times its rated load.
Make sure any component of a hoisting machine that needs to be lubricated for protection or proper functioning has means provided to apply the lubricant.
Make sure winding drums, traction drums and sheaves, and directional sheaves used in conjunction with hoisting machines are compatible with, and sized for, the wire rope used.
Make sure each winding drum:
Has a positive means to attach the wire rope to the drum;
AND
The attachment can develop at least four times the rated load of the hoist.
Make sure each hoisting machine is provided with a primary brake that is all of the following:
Capable of stopping and holding not less than one hundred twenty-five percent of the lifting capacity of the hoist
Directly connected to the drive train of the hoisting machine without using belts, chains, clutches, or set screw type devices
Automatically set when power to the prime mover is interrupted.
Make sure each hoisting machine is provided with at least one independent secondary brake that is all of the following:
Capable of stopping and holding not less than one hundred twenty-five percent of the lifting capacity of the hoist
An automatic emergency type of brake that, if actuated during each stopping cycle, does not engage before the hoist is stopped by the primary brake
Able to stop and hold the platform within a vertical distance of twenty-four inches (609.6 mm) after the brake is actuated.
| Reference: | Moving parts of a hoisting machine need to be enclosed or guarded as required by another chapter, Machine safety, chapter 296-806 WAC. |
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You must:
Make sure each suspended unit component is:
Capable of supporting, without failure, at least four times the maximum intended live load applied or transmitted to it;
AND
Constructed of materials that will withstand the
anticipated weather conditions.
| Exemption: | The strength requirement does not apply to suspension ropes and guardrail systems. |
Make sure each suspended unit has a load rating plate that:
Is conspicuously located;
AND
States the suspended unit weight and rated load.
Make sure suspended units that do not have the suspension points at the end of the unit:
Are continuously stable for any position or use of the live load;
AND
Maintain at least a one and one-half to one stability factor against unit upset.
Make sure each suspended unit has guide rollers, guide shoes, or building face rollers that compensate for variations in building dimensions and for minor horizontal out-of-level variations of the suspended unit.
Make sure the working platform of each suspended unit is secured to the building facade by at least one of the following methods:
Continuous engagement to building anchors
Intermittent engagement to building anchors
Button guide engagement
Angulated roping and building face rollers
A system equivalent to continuous engagement to building anchors.
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Make sure each working platform of a suspended unit has a guardrail system on all sides that consists of a top guardrail, midrail, and a toeboard.
Make sure the top guardrail is:
At least thirty-eight inches (950 mm) high;
AND
Able to withstand at least a two hundred pound (890 n) force in any downward or outward direction.
Make sure the midrail is able to withstand at least a seventy-five pound (333 n) force in any downward or outward direction.
Make sure material encloses the area:
Between the top guardrail and the toeboard on the ends and outboard side of the platform;
AND
Between the midrail and the toeboard on the inboard side of the platform.
Make sure the material surrounding the platform is:
Able to withstand a load of one hundred pounds (45.4 kg) applied horizontally over any area of one square foot (.09 m2);
AND
Has openings small enough to not allow passage of life lines and potential falling objects.
Make sure toeboards are all of the following:
Capable of withstanding, without failure, a force of at least fifty pounds (222 n) applied at any point in a downward or horizontal direction
At least four inches (9 cm) from their top edge to the level of the platform floor
Securely fastened in place at the outermost edge of the platform
Installed so there is not more than a one-half inch (1.3 cm) gap between the bottom of the toeboard and the platform floor
Solid or with openings not more than one inch (2.5 cm) in the greatest dimension.
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You must:
Make sure the width of the working platform is:
At least twenty-four inches (610 mm);
AND
Allows a minimum of a twelve-inch (305 mm) wide passage at or past any obstruction on the platform.
Make sure the platform has slip-resistant flooring.
Make sure any opening in the platform is either:
Small enough to prevent passage of life lines, cables, and other potential falling objects;
OR
Protected by material under the opening which prevents the passage of life lines, cables, and potential falling objects.
Make sure means are provided to store any cable suspended from above the platform to keep it from accumulating on the floor of the platform.
Make sure means are provided to secure all tools, water tanks, and other accessories to keep them from moving or accumulating on the floor of the platform.
Make sure flammable liquids are not carried on the working platform.
Make sure a type B-C portable fire extinguisher is provided and securely attached on all working platforms.
Make sure operating controls for vertical travel of the platform are:
Continuous-pressure type;
AND
Located on the platform.
Make sure the maximum rated speed of the platform is limited to:
Fifty feet per minute (0.3 ms) for single speed hoists;
AND
Seventy-five feet per minute (0.4 ms) for multispeed hoists.
Make sure access to and egress from a working platform, except for those that land directly on a safe surface, is provided by stairs, ladders, platforms or runways.
Make sure access gates are self-closing and
self-latching.
| Reference: | Requirements for stairs, ladders, platforms and runways are found in other chapters: |
| Working Surfaces, Guarding Floors and Wall Openings, Ladders, Part J-1 in the General safety and health standards, chapter 296-24 WAC | |
| Scaffolds, chapter 296-874 WAC | |
| Ladders, portable, chapter 296-876 WAC. |
Make sure a suspended platform's suspension system restricts the platform inboard to outboard roll around its longitudinal axis to not more than fifteen degrees from the horizontal when moving the live load from the inboard to the outboard side of the platform.
| Note: | The roll limitation does not apply to supported equipment. |
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You must:
Make sure a secondary wire rope suspension system which prevents the platform from falling if the primary means of support fails is provided on:
Working platforms that contain overhead structures which restrict emergency egress;
AND
Single-point suspended working platforms.
Make sure each person on the working platform is provided with a fall arrest system that:
Meets the requirements of Appendix C -- Personal fall arrest system, WAC 296-24-88050, found in the General safety and health standards, chapter 296-24 WAC;
AND
Uses a horizontal lifeline or direct connection anchorage on platforms that contain overhead structures which restrict emergency egress.
Make sure platforms suspended by two or more wire ropes are provided with vertical lifelines if failure of one wire rope or suspension attachment will cause the platform to upset.
| Note: | Vertical lifelines are not required for the fall arrest system if a secondary wire rope suspension is used and each person is attached to a horizontal lifeline anchored to the platform. |
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IMPORTANT:
In addition to these requirements, you also need to meet the requirements of both of the following sections in this chapter:
Suspended working platforms and manned platforms used on supported equipment, WAC 296-870-70050
Working platform fall protection, WAC 296-870-70055.
You must:
Make sure an emergency electric operating device is provided on roof powered platforms that:
Can be used if either the normal operating device located on the platform or the cable connected to the platform fails;
AND
Is mounted in a secured compartment near the hoisting machine.
Make sure the secured compartment containing the emergency electric operating device:
Is labeled with instructions for using the emergency electric operating device;
AND
Has means for opening the compartment mounted in:
&sqbul; A break-glass receptacle near the emergency electric operating device;
OR
&sqbul; An equivalent secure and accessible location.
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IMPORTANT:
In addition to these requirements, you also need to meet the requirements of both of the following sections in this chapter:
Suspended working platforms and manned platforms used on supported equipment, WAC 296-870-70050
Working platform fall protection, WAC 296-870-70055.
You must:
Make sure, after each day's use, ground-rigged working platforms are:
Disconnected from the power supply within the building;
AND
Disengaged from its suspension points or secured and stored at grade.
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IMPORTANT:
In addition to these requirements, you also need to meet the requirements of both of the following sections in this chapter:
Suspended working platforms and manned platforms used on supported equipment, WAC 296-870-70050;
Working platform fall protection, WAC 296-870-70055.
You must:
Make sure each stabilizer tie is equipped with a "quick connect - quick disconnect" device for attachment to the building anchor that:
Cannot be accidentally disengaged;
AND
Is resistant to adverse environmental conditions.
Make sure the platform has a stopping device that will interrupt the hoist power supply in the event the platform contacts a stabilizer tie during its ascent.
Make sure intermittently stabilized platforms use stabilizer ties that:
Allow the specific attachment length needed to obtain the predetermined angulation of the suspended wire rope;
AND
Maintain the specific attachment length at all building anchor locations.
Make sure stabilizer ties can be attached and removed without horizontal movement of the platform.
Make sure platform-mounted equipment and suspension wire ropes:
Will not be damaged by the loads from the stabilizer tie or its building anchor;
AND
Are able to withstand a load that is at least twice the ultimate strength of the stabilizer tie.
Make sure building face rollers are placed so they do not contact exterior anchors used on the building face.
Make sure the platform maintains continuous contact with the building face while ascending and descending.
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IMPORTANT:
In addition to these requirements, you also need to meet the requirements of both of the following sections in this chapter:
Suspended working platforms and manned platforms used on supported equipment, WAC 296-870-70050;
Working platform fall protection, WAC 296-870-70055.
You must:
Make sure two guide tracks are mounted on the platform and provide continuous contact with the building face.
Make sure each guide track on the platform meets all of the following:
Engages a minimum of two guide buttons during any vertical travel of the platform after the initial button engagement
Is sufficiently maneuverable by platform occupants to permit easy engagement of the guide buttons
Can be easily moved into and out of its storage position on the platform.
Make sure each guide track on the platform of a roof-rigged system has a storage position on the platform.
Make sure load carrying components of the button guide stabilization system which transmit the load into the platform are either:
Able to support the weight of the platform;
OR
Are prevented by the guide track connectors or platform attachments from having the weight of the platform transmitted to the platform attachments.
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IMPORTANT:
Manned platforms used on supported equipment need to meet all the requirements, except the inboard to outboard roll limitation, of suspended working platforms and manned platforms used on supported equipment, WAC 296-870-60050.
You must:
Make sure supported equipment uses means other than friction to maintain a vertical position relative to the face of the building.
Make sure cog wheels or equivalent means are incorporated to provide climbing traction between the supported equipment and the building guides.
Make sure additional guide wheels or shoes are incorporated as necessary to keep the drive wheels continuously in positive engagement with the building guides.
Make sure that, at the point where the drive wheels enter the building guides, proper alignment is maintained using launch guide mullions that are:
Indexed to the building guides;
AND
Retained in alignment with the building guides.
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You must:
Make sure each specific installation uses suspension wire ropes and connections or combination cable and connections meeting the specifications recommended by the hoisting machine manufacturer.
Make sure connections are capable of developing at least eighty percent of the rated breaking strength of the wire rope.
Make sure each suspension rope has a design factor of at least ten.
Definition:
The design factor is the ratio of the rated strength of the suspension wire rope to the rated working load. It is calculated using the following formula:
F = (S x N)/W Where:
F = Design factor
S = Manufacturer's rated strength of one suspension rope
N = Number of suspension ropes under load
W = Rated working load on all ropes at any point of travel.
Example:
A working platform is suspended by 4 wire ropes (N), each having a rated strength (S) of three thousand pounds. The rated working load of the platform (W) is one thousand pounds.
Calculate the design factor (F) as follows:
F = (S x N)/W = (3000 x 4)/1000 = 12000/1000 = 12
You must:
Make sure the minimum grade of suspension wire rope used is improved plow steel or equivalent.
Make sure suspension wire ropes are sized to conform with the required design factor, but never less than 5/16 inch (7.94 mm) in diameter.
Make sure there is not more than one reverse bend in six wire rope lays.
Make sure a suspension wire rope that is to be used at a specific location, and will remain at that location, has a corrosion-resistant tag that:
Is securely attached to one of the wire rope fastenings;
AND
Bears the following wire rope information:
&sqbul; Diameter in inches or millimeters (mm)
&sqbul; Construction classification
&sqbul; Whether nonpreformed or preformed
&sqbul; Grade of material
&sqbul; Manufacturer's rated strength
&sqbul; Manufacturer's name
&sqbul; Month and year the ropes were installed
&sqbul; Name of the person or company which installed the ropes.
Make sure a new tag is installed at each wire rope renewal.
Make sure when resocketing the wire rope either:
The original tag is stamped with the date of resocketing;
OR
The original tag Is retained and a supplemental tag added that shows:
&sqbul; The date of resocketing;
AND
&sqbul; The name of the person or company that resocketed the rope.
Make sure winding drum type hoists contain at least three wraps of the suspension wire rope on the drum when the suspended unit has reached the lowest possible point of its vertical travel.
Make sure traction drum and sheave type hoists use wire rope long enough to reach the lowest possible point of vertical travel of the suspended unit, and an additional length of the wire rope of at least four feet (1.2 m).
Make sure suspension wire rope is never lengthened or repaired.
Make sure babbitted fastenings are never used with suspension wire rope.
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| Reference: | Unless otherwise specified in this chapter, make sure electrical wiring and equipment meet the requirements of Electrical, Part L in the General safety and health standards, chapter 296-24 WAC. |
Make sure electrical runway conductor systems are:
Designed for use in exterior locations;
AND
Located so they do not come in contact with accumulated snow or water.
Make sure cables are protected against damage resulting from over-tensioning or other causes.
Make sure the control system requires the operator to follow predetermined procedures to operate suspended or supported equipment.
Make sure the control system has:
Devices included to protect the equipment against electrical overloads, three-phase reversal and phase failure;
AND
A separate method that is independent of the direction control circuit to break the power circuit in case of an emergency or malfunction.
Make sure installations where the carriage does not have a stability factor of at least four against overturning have electrical contacts provided and connected so that the operating devices for suspended or supported equipment will only function when the carriage is located and mechanically retained at an established operating point.
Make sure the hoisting or suspension system has overload protection to prevent the equipment from operating in the "up" direction with a load greater than one hundred twenty-five percent of the rated load of the platform.
Make sure an automatic detector is provided for each suspension point that will do both of the following if a suspension wire rope becomes slack:
Interrupt power to all hoisting motors for travel in the "down" direction;
AND
Apply the primary brakes.
| Note: | A continuous-pressure rigging-bypass switch designed for use during rigging is permitted. It can only be used during rigging. |
Make sure upper and lower directional switches are provided that are designed to prevent the travel of suspended units beyond safe upward and downward levels.
Make sure remote controlled, roof-powered manned platforms have an emergency stop switch located adjacent to each control station on the platform.
Make sure cables which are in constant tension have overload devices which will prevent the tension in the cable from interfering with:
The device that limits the hoist from lifting a load greater than one hundred twenty-five percent of the rated load of the platform;
AND
The platform roll limiting device required by WAC 296-870-70050, Suspended working platforms and manned platforms used on supported equipment.
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Anemometer. An instrument for measuring wind velocity.
Angulated roping. 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 rollers. A specialized form of guide roller 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. Operations such as window cleaning, caulking, metal polishing, reglazing, and general maintenance on building surfaces.
Cable. A conductor, or group of conductors, enclosed in a weatherproof sheath, that may be used to:
Supply electrical power or control current for equipment;
OR
Provide voice communication circuits.
Carriage. A wheeled vehicle used for the horizontal movement and support of other equipment.
Certification. A written, signed, and dated statement confirming the performance of a requirement.
Combination cable. 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. Someone who:
Is capable of identifying existing and predictable hazards in the surroundings or working conditions which are unsanitary, hazardous, or dangerous to employees;
AND
Has the authority to take prompt corrective measures to eliminate them.
Continuous pressure. Operation of a control by requiring constant manual actuation for the control to function.
Control. A system or mechanism used to regulate or guide the operation of equipment.
Davit. 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.
Design factor. The ratio of the rated strength of the suspension wire rope to the rated working load. It is calculated using the following formula:
F = (S x N)/W Where:
F = Design factor
S = Manufacturer's rated strength of one suspension rope
N = Number of suspension ropes under load
W = Rated working load on all ropes at any point of travel.
Equivalent. Alternative design, material or method to protect against a hazard. You have to demonstrate it provides an equal or greater degree of safety for employees than the method, material or design specified in the rule.
Existing installation. A permanent powered platform installation that:
Was completed before July 23, 1990;
AND
Has had no major modification done after July 23, 1990.
Ground rigging. A method of suspending a working platform starting from a safe surface to a point of suspension above the safe surface.
Ground rigged davit. A davit which cannot be used to raise a suspended working platform above the building face being serviced.
Guide button. A building face anchor designed to engage a guide track mounted on a platform.
Guide roller. A rotating cylindrical member that provides continuous engagement between the suspended or supported equipment and the building guides. It may operate separately or as part of a guide assembly.
Guide shoe. A device that is similar to a guide roller but is designed to provide a sliding contact between the shoe and the building guides.
Hoisting machine. A device intended to raise and lower a suspended or supported unit.
Installation. A powered platform installation consists of all the equipment and the parts of the building involved with using the powered platform for building maintenance.
Interlock. A device designed to ensure that operations or motions occur in proper sequence.
Intermittent stabilization. A method of platform stabilization in which the angulated suspension wire ropes are secured to regularly spaced building anchors.
Lanyard. A flexible line of rope, wire rope or strap which is used to secure the body harness to a deceleration device, lifeline or anchorage.
Lifeline. A component consisting of a flexible line that connects to an anchorage at one end to hang vertically (vertical lifeline), or that connects to anchorages at both ends to stretch horizontally (horizontal lifeline). It serves as a means for connecting other components of a personal fall arrest system to the anchorage.
Live load. The total static weight of workers, tools, parts, and supplies that the equipment is designed to support.
New installation. A permanent powered platform installation that was completed, or an existing installation that has had major modifications done, after July 23, 1990.
Operating control. A mechanism regulating or guiding the operation of equipment that makes sure the equipment operates in a specific mode.
Operating device. A push button, lever, or other manual device used to actuate a control.
Outrigger. 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.
Poured socket. A method of providing wire rope termination in which the ends of the rope are held in a tapered socket by means of poured spelter or resins.
Primary brake. A brake designed to be applied automatically whenever power to the prime mover is interrupted or discontinued.
Prime mover. The source of mechanical power for a machine.
Rated load. The manufacturer's specified maximum load.
Rated strength. 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. The combined static weight of workers, materials, and suspended or supported equipment.
Registered professional engineer. 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. A powered platform having the raising and lowering mechanism located on the roof.
Roof-rigged davit. 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. The equipment, such as wire rope, that is used to suspend a component of an equipment installation.
Safe surface. A horizontal surface that provides reasonable assurance that personnel occupying the surface will be protected from falls. This protection can be provided by location, a fall protection system, or other equivalent method.
Secondary brake. A brake designed to arrest the descent of the suspended or supported equipment in the event of an overspeed condition.
Stability factor. The ratio of the stabilizing moment to the overturning moment.
Stabilizer tie. A flexible line connecting the building anchor and the suspension wire rope supporting the platform.
Supported equipment. Building maintenance equipment that is held in or moved to its working position by means of attachment directly to the building or extensions of the building being maintained.
Suspended equipment. 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.
Tie-in guides. 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.
Transportable outriggers. Outriggers designed to be moved from one work location to another.
Type F powered platform. A powered platform that has both of the following characteristics:
The working platform is suspended by at least four wire ropes and designed so that failure of any one wire rope will not substantially alter the normal position of the working platform
Only one layer of hoisting rope is permitted on the winding drums.
Type T powered platform. A powered platform installation that has a working platform suspended by at least two wire ropes. The platform will not fall to the ground if a wire rope fails, but the working platform's normal position would be upset.
Weatherproof. Constructed or protected so that exposure to the weather will not interfere with successful operation.
Winding drum hoist. A type of hoisting machine that accumulates the suspension wire rope on the hoisting drum.
Working platform. The suspended or supported equipment intended to provide access to the face of the building and manned by persons engaged in building maintenance.
Wrap. One complete turn of the suspension wire rope around the surface of a hoist drum.
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