Everyday rules

• A competent person inspects the excavation, the adjacent areas and the protective systems daily before work starts, after every rainstorm or other event that could increase hazards, and as conditions change.
• Locate underground utilities before digging, and protect, support or remove them as the work goes on.
• Keep excavated soil, called spoil, and other material at least 2 feet from the edge.
• Provide a ladder, stairway, ramp or other safe way out in every trench 4 feet deep or more, so that no worker needs to travel more than 25 feet sideways to reach it.
• Provide a way to keep workers from falling into the excavation, and wear high visibility clothing near traffic.
• Never work under loads that are being lifted or moved over the excavation, and keep vehicles and equipment away from the edge unless the system is designed for them.
• Where water collects, do not let workers work in the excavation unless special precautions, such as pumping and supervision by a competent person, are in place.

Materials and equipment

The employer must make sure that:

• materials and equipment used for protective systems are not damaged or defective
• manufactured equipment is stored as the maker directs and in a way that prevents exposure to hazards
• damaged or defective equipment is taken out of service and not used again until a registered professional engineer has evaluated and approved it

Atmospheres in which no one may work

Do not allow workers to work in an atmosphere:

• with less than 19.5 percent or more than 23.5 percent oxygen
• with a combustible gas concentration of more than 20 percent of the lower flammable limit
• where airborne contaminants exceed the exposure limits

Test the air in an excavation more than 4 feet deep before workers enter if there is a reasonable possibility of a hazardous atmosphere, and keep testing as conditions require. Provide emergency rescue equipment where there may be a hazardous atmosphere.

A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.