Working in Confined, Sloped, and Hazardous Conditions
Working in Confined, Sloped, and Hazardous Conditions
This domain tests setup and operation where clearance, stability, atmosphere, or utilities are compromised. Expect questions on confined spaces, slopes, overhead lines, and buried services.
Core rules
- Confined space: use a permit-required program; test atmosphere before entry-oxygen 19.5–23.5%, LEL below 10%, toxics below exposure limits; ventilate; use an attendant. Never enter to rescue without protection.
- Excavator in a confined area: maintain clearance for swing and counterweight, use a spotter, slow mode, and exhaust ventilation.
- Slopes: assess stability, avoid side slopes, bench if needed, keep tracks aligned with the slope, and keep the bucket low.
- Overhead lines: keep at least 10 ft (3 m) for lines up to 50 kV and greater distances for higher voltages under OSHA 1926.1408; use a spotter and physical limit markers.
- Buried utilities: hand-dig the tolerance zone; stop if markings are unclear.
- Hazardous site: traffic control, lighting, dust suppression, and no entry into unsupported trenches.
Worked example
A 25 kV line crosses the swing path. Reasoning: 25 kV is below 50 kV, so the minimum is 10 ft (3 m). Add margin for boom flex, wind, and operator error; mark the limit and use a spotter. Rubber tracks do not insulate the machine.
Traps
- Entering a trench to rescue a worker without PPE or testing.
- Assuming rubber tracks insulate against electricity.
- Traveling across a side slope.
- Digging near a utility without hand excavation.