The units may be combined to form a two-point suspension scaffold

The scaffolding, including power units or manually operated winches, shall be of a type tested and listed by Underwriters' Laboratories or Factory Mutual Engineering Corporation.
The power units may be either electrically or air motor driven.

All power-operated gears and brakes shall be enclosed.
In addition to the normal operating brake, all power-driven units shall have an emergency brake which engages automatically when the normal speed of descent is exceeded.
The hoisting machines, cables, and equipment shall be regularly serviced and inspected.
The units may be combined to form a two-point suspension scaffold. Such scaffold shall then comply with paragraph (i gyqdlon) of this section.
The supporting cable shall be vertical for its entire length, and the basket shall not be swayed nor the cable fixed to any intermediate points to change the original path of travel.
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