CSLB C-46 Solar ContractorSafetyMedium
A solar crew is installing modules on a steep commercial roof that requires the use of a ladder to access the work area. The base of the ladder is placed 10 feet from the wall. What is the ideal working length of the ladder to maintain the safest angle?
- A20 feet
- B30 feet
- C45 feet
- D40 feet
Show answer & explanationAnswer & explanation
Correct answer: D. 40 feet
The 4:1 rule for ladder safety states that for every 4 feet of working ladder length, the base should be 1 foot away from the wall. If the base is 10 feet from the wall, the ideal working length is 10 feet * 4 = 40 feet.
Why the other options are wrong
- A. Incorrect. This would result in a 2:1 ratio, which is too steep and unstable.
- B. Incorrect. This would result in a 3:1 ratio, still too steep.
- C. Incorrect. This would result in a 4.5:1 ratio, which is too shallow and could cause the ladder to slide.
Ladder 4:1 Rule
The 4:1 ladder rule states that for every 4 feet of vertical working height, the base of the ladder should be placed 1 foot horizontally away from the wall or support structure.
- Ensures optimal ladder stability and angle.
- Prevents ladder from sliding out or tipping backward.
- Working length is the distance from the base to the support point.
Memory trick: Four up, one out, keeps the ladder stout.