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Subchapter 7. General Industry Safety Orders
Group 4. General Mobile Equipment and Auxiliaries
Article 24. Elevating Work Platforms and Aerial Devices
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§3639. Factors of Safety in Design of Work Platform Assembly.

(a) Where the platform is supporting its rated work load by a system of wire ropes or lift chains, or both, the safety factor of the wire rope or chain system shall not be less than 8 to 1 based on ultimate strength.

(b) All critical components of a hydraulic or pneumatic system used in a work platform shall have a bursting strength that exceeds the pressure attained when the system is subjected to the equivalent of four times the rated work load. Critical components are those in which a failure would result in a free fall or free rotation of the boom. All noncritical hydraulic components shall have a bursting safety factor of at least 2 to 1.

(c) Automatic safety devices or systems shall be provided to prevent free fall of the work platform should a failure of the power supply or elevating system occur.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment filed 10-12-84; effective thirtieth day thereafter (Register 84, No. 41).

2. Amendment of subsection (a) filed 2-27-2006; operative 3-29-2006 (Register 2006, No. 9).

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