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WCB Standards

WCB Standard: WPL 3-2004 Safety Factor and Minimum Breaking Strength for Suspended Work Platforms and Associated Components

© Workers' Compensation Board of British Columbia. All rights reserved. No part of this document may be copied, reproduced, or distributed for profit or other commercial enterprise, nor may any part be incorporated into any other publication, without written permission of the Workers' Compensation Board of B.C.

1. Scope

This Standard applies to suspended work platforms including the following: swing stages, portable power platforms, catenary scaffolds, needle beam scaffolds, outrigger or suspended mason's scaffold, work platform suspended from a crane and boatswain's chairs.

This Standard does not cover the following types of platforms: permanent powered platform, fixed platform suspended from structures by wire rope or chains, platforms intended solely for lifting material or platform suspended under aircraft.

The associated components include the platform, suspension lines, rigging and anchor system except for permanently mounted roof anchors.

2. Definitions

"Safety Factor" means the theoretical reserve capability of a product, determined by dividing the breaking strength by the rated working load unless otherwise noted.

3. Safety factor

(1) Rigging and suspension lines except for a catenary line used to support work platforms must have a safety factor of at least 10.

(2) A catenary line installed specifically to support a catenary scaffold must have a safety factor of at least 6.

(3) A hanger or stirrup used for supporting a swing stage must have a safety factor of at least 10.

(4) Cornice hook, parapet clamps, thrust out beams and other anchoring devices must have a safety factor of at least 4 based on the ultimate load carrying capacity to the static load.

(5) A thrust out beam must be counter-balanced to support a load of at least 4 times the static load.

(6) A suspended work platform must have a safety factor of at least 4 based on the ratio of the ultimate load carrying capacity of the work platform to the rated load.

4. Minimum breaking strength

(1) The tiebacks for anchoring devices must have a minimum breaking strength of 22 kN (5,000 lbs)

(2) A rope used to suspend a swing stage or similar equipment must be a wire rope or a synthetic rope that has a minimum breaking strength of 22 kN (5,000 lbs).

(3) A rope used to suspend a boatswain's chair by block and tackle must be a wire rope or a synthetic rope that has a minimum breaking strength of 22 kN (5,000 lbs).

(4) A rope used to suspend a boatswain's chair by other than a block and tackle must be a synthetic rope that has a minimum breaking strength of 27 kN (6,000 lbs).

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