- (1) 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.
- (2) You must never use a material that can flow as a counterweight to achieve stability.
- (3) You must make sure the stability factor against overturning for horizontal traversing of the carriage, including wind and impact effects, is not less than two.
- (4) You must 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.
- (5) You must 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.
- (6) You must 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.
[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050. WSR 15-23-086, § 296-870-70015, filed 11/17/15, effective 12/18/15. Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 47.17.060. WSR 06-19-075, § 296-870-70015, filed 9/19/06, effective 1/1/07.]