It depends on the work type and the regulation that applies:

• Federal OSHA (general industry): commonly 4 ft. for unprotected sides/edges.
• Federal OSHA (construction): commonly 6 ft. for many construction activities.
• Cal-OSHA (California): many construction scenarios use 7.5 ft. as a key trigger height, but California also has task-specific rules (roofing is a common example). Cal DIR

Because exceptions and task-specific rules are common (roof edges, ladders, platforms, leading edges, skylights, etc.), the safest approach is to treat fall hazards as a site-specific assessment, not a single universal number.

Related CAISS resources:

• Guardrail Systems (Fall Prevention)
• Warning Line Systems
• Fall Protection Inspection, Site Survey, Safety Training