R 408.10124 Guarding cup wheels.

Rule 124. (1) A cup wheel on a portable grinder shall be protected by a band-type guard. (2) A band-type guard shall be constructed as prescribed in figures 6 and 7 of R 408.10198 and tables 4 and 5 of R 408.10199 and adjusted within 1/2 inch of the working surface of the abrasive wheel. (3) A revolving cup guard shall not be used as a method of safeguarding. (4) A guard for a tool and cutter grinder cup wheel shall be not less than 180 degrees of the periphery and the back side of the wheel shall be guarded. The spindle end and nut and front of the wheel need not be guarded if the spindle end and nut are inside the plane of the working face of the wheel. See figure 5 of R 408.10198.