PDFWAC 296-870-70090
Control circuits, power circuits and electrical protective devices.
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. |
(1) You must make sure electrical runway conductor systems are:
(a) Designed for use in exterior locations; and
(b) Located so they do not come in contact with accumulated snow or water.
(2) You must make sure cables are protected against damage resulting from over-tensioning or other causes.
(3) You must make sure the control system requires the operator to follow predetermined procedures to operate suspended or supported equipment.
(4) You must make sure the control system has:
(a) Devices included to protect the equipment against electrical overloads, three-phase reversal and phase failure; and
(b) A separate method that is independent of the direction control circuit to break the power circuit in case of an emergency or malfunction.
(5) You must 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.
(6) You must 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.
(7) You must 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:
(a) Interrupt power to all hoisting motors for travel in the "down" direction; and
(b) 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. |
(8) You must 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.
(9) You must make sure remote controlled, roof-powered manned platforms have an emergency stop switch located adjacent to each control station on the platform.
(10) You must make sure cables which are in constant tension have overload devices which will prevent the tension in the cable from interfering with:
(a) 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
(b) The platform roll limiting device required by WAC 296-870-70050, Suspended working platforms and manned platforms used on supported equipment.