§1533. Internal Combustion Engines.

(a) Internal combustion engine-driven equipment shall be operated inside buildings or enclosed structures, or, if they are 20 feet or less in depth, inside shafts, culverts, and pipelines, only when such operation does not result in exposure to dangerous gases or fumes in concentrations above the maximum acceptable limits listed in Section 5155 of the General Industry Safety Orders. Some acceptable methods of control are:

(2) Providing a system of building ventilation that dilutes and removes exhaust products to outside atmosphere.

(3) Installing effective, catalyst-type exhaust treatment units on the engines.

(b) When internal combustion engine-driven equipment is operated in shafts that are 20 feet or less in depth into which employees enter, culverts into which employees enter, or pipelines into which employees enter and when a hazardous atmosphere exists or could be reasonably expected to exist, a mechanical ventilation system shall be provided to prevent exposure to internal combustion engine emissions. The ventilation system, which may consist of a mechanical exhaust system, a forced air ventilation (blower) system or a combination of the two, shall:

(1) Supply fresh air at a minimum of 60 lineal feet per minute through the area where the engine is operated;

(2) Supply at least 100 cubic feet of fresh air per minute per engine brake horsepower of the internal combustion engine used;

(3) Supply a minimum of 200 cubic feet of fresh air per minute for each person that enters the space, and

(4) Be inspected by a competent person at the beginning of each shift, or more frequently, to ensure an effective supply of fresh air.

(c) When internal combustion engine-driven equipment is operated in excavations that are greater than 4 feet in depth into which employees enter, and a hazardous atmosphere exists or could be reasonably expected to exist, employees shall be protected in accordance with the requirements of Section 1541(g).

(d) If any work location subject to subsection (b) is subject to confined space safety orders contained in these orders, the General Industry Safety Orders or other Title 8 safety orders, and if the provisions of subsection (b) are less protective than a confined space safety order, the confined space safety order shall take precedence.

NOTE: For shafts greater than 20 feet in depth and excavations subject to the Tunnel Safety Orders, refer to Title 8, Division 1, Chapter 4, Subchapter 20, the Tunnel Safety Orders.