A worker is performing welding operations 18 feet above ground level on a flat roof. The roof edge has no parapet or guardrail. What fall protection is required?
Correct Answer
C) Personal fall arrest system or guardrail system
At 18 feet above ground, fall protection is required. Since it's a roof edge without existing protection, either a personal fall arrest system or guardrail system must be used.
Why This Is the Correct Answer
At 18 feet — well above the 6-foot construction trigger — fall protection is mandatory. On a flat roof with an unprotected edge, OSHA 29 CFR 1926.502 requires either a personal fall arrest system (PFAS) or a guardrail system. These are conventional fall protection methods that physically prevent or arrest a fall.
Why the Other Options Are Wrong
Option A: Safety monitoring system only
A safety monitoring system alone is only permitted as an exception for certain low-slope roofing work and requires very specific conditions (roof slope <4:12, area too small for other systems, etc.). It is not sufficient as the sole measure when conventional systems can be used at an unprotected roof edge at 18 feet.
Option B: No fall protection required on flat surfaces
There is no OSHA exemption for flat surfaces. The 6-foot rule applies regardless of roof pitch. Flat roofs with unprotected edges present significant fall hazards.
Option D: Warning line system only
Warning line systems are permitted only for low-slope roofs and must be combined with other measures (safety monitoring or PFAS) when workers are between the warning line and the roof edge. A warning line alone is insufficient at an unprotected roof edge.
Memory Technique
At a roof edge with nothing between the worker and the drop: 'Guard it or Arrest it.' Guardrail system or Personal Fall Arrest System — those are the two strong options. Everything else requires special conditions.
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