Safety Standards for Window Cleaning

Chapter 296-878, WAC

Effective Date: 01/01/03

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WAC 296-878-190
Boatswains' chairs

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You must:

Select appropriate boatswains' chairs

Safely use boatswains' chairs rigged with a block and tackle


WAC 296-878-19005

Select appropriate boatswains' chairs.

You must

(1) Make sure that when you use a block and tackle, it is the correct size, including:

  • Correctly-sized ball bearings or bushed blocks
  • Safety hooks
  • Eye-spliced rope
  • A minimum breaking strength of 5 thousand pounds.

(2) Make sure all rope used with a boatswain's chair has a minimum breaking strength of 5 thousand pounds, including rope used for:

  • Suspension
  • Block and tackle
  • Seat slings.

(3) Make sure the ropes on boatswain's chair seat slings:

  • Are reeved through the 4 corner holes in the seat
  • Cross each other on the underside of the seat
  • Are rigged so the chair can’t slip out of a level position.

WAC 296-878-19010

Safely use boatswains' chairs rigged with a block and tackle.

You must

(1) Make sure the rated capacity or the maximum intended load, whichever is less, isn’t exceeded.

(2) Make sure the suspension rope stays vertical between the boatswain's chair and suspension device unless all of these requirements are met:

  • The rigging has been designed by a qualified person
  • The scaffold can be easily reached by rescuers
  • The suspension rope is protected from damage when a change in direction occurs
  • The scaffold won’t swing and contact another surface.

(3) Make sure a suspension height of 75 feet above grade or building setback isn’t exceeded.



Suspension height may be up to 130 feet above grade or building setback if the boatswain's chair block and tackle has all of the following:

  • An automatic braking system
  • A design that minimizes the amount of force required to raise or lower the suspended worker
  • An automatic braking system that automatically maintains an elevation when no force is applied to the tackle
  • A system that doesn’t slip.

You must

(4) Prohibit tying any kind of knot in a block and tackle system to maintain elevation.

(5) Make sure another worker is stationed below any boatswain's chair rigged with a block and tackle who can assist the suspended employee.

(6) Make sure workers don’t attempt to increase the work area by swinging, swaying, or other maneuvers.

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