Safety第 97 / 110 题
A plumber sets an extension ladder to reach a roof vent terminal. Using the 4-to-1 rule, how far should the base be from the wall if the ladder contacts the wall 16 ft up?
a.4 ft
b.2 ft
c.8 ft
d.16 ft
解析
The 4-to-1 rule places the base 1 ft out for every 4 ft of working height, so 16 / 4 = 4 ft from the wall. This angle keeps the ladder from sliding out at the base or tipping back. The ladder should also extend at least 3 ft above the roof edge for a safe transition.
法律依据: 29 CFR 1926.1053免费刷完整 110 道题库 — 无需注册。
同考点相关题目
- A trench is 3 ft wide, 6 ft deep, and 40 ft long. How many cubic yards of spoil are generated (27 cubic feet per cubic yard), a figure needed to plan the 2 ft edge setback and haul-off?
- A plumber must enter a sanitary sewer manhole to make a connection. This is a permit-required confined space. What atmospheric hazard is the leading concern, and what is required before entry?
- Before entry, a manhole 4 ft in diameter and 12 ft deep must be purged with 5 air changes. Using volume = 0.785 x diameter^2 x depth (about 151 ft^3), what total air volume must be moved to complete the purge?
- Backflow prevention is a public-health safety requirement. What health event does a properly working backflow assembly prevent?
- A master plumber must braze medical gas copper, which is hot work. What fire-safety precaution is required before starting?
- A plumber replaces piping in a building constructed before 1978 and disturbs old painted surfaces and solder. What two legacy hazards require specific precautions?