(1) General.

(a) Workers must not leave shingle machines unattended while the carriage is in motion.

(b) Shingle blocks must not be piled more than one tier high on tables or roll cases. Chunks may be placed horizontally one tier high on top of shingle blocks. Shingle blocks must be piled in a stable manner, not more than seventy-two inches high, within the immediate working area of the shingle sawyer or the area must be barricaded.

(c) Provisions must be made to prevent blocks from falling into the packing area.

(d) On each machine operated by electric motors, positive means must be provided for rendering such controls or devices inoperative while repairs or adjustments are being made to the machines they control.

(e) Workers must not stand on top of blocks while in the process of splitting other blocks into bolts.

(2) Jointers (shingle). Shingle jointers must have the front, or cutting face of the knives, housed except for a narrow slot through which the shingles may be fed against the knives.