# AI tells a worker to set up an extension ladder at a 60-degree angle by placing the base close to the wall (e.g., 1 foot out for every 4 feet of height)

- **ID:** `safety/ladder-angle-incorrect`
- **Domain:** safety
- **Category:** system_error
- **Error Code:** `LADDER-ANG-304`
- **Verification:** ai_generated
- **Fix Rate:** 92%

## Root Cause

The correct safe angle for an extension ladder is approximately 75.5 degrees from horizontal (4:1 ratio: base 1 foot out for every 4 feet of vertical height to the support point), not 60 degrees; a 60-degree angle (1:4 ratio) places the base too close to the wall, increasing the risk of the ladder tipping backward or sliding out, and OSHA 1926.1053(b)(1) specifies the 4:1 ratio.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| OSHA 29 CFR 1926.1053 (2024) | active | — | — |
| ANSI A14.2-2022 (Ladder Safety) | active | — | — |
| NFPA 1932-2023 (Fire Service Ladders) | active | — | — |

## Workarounds

1. **Use the 4:1 ratio: for every 4 feet of vertical height to the support point, place the base 1 foot away from the vertical line. Example: If the ladder rests against a wall at 20 feet height, the base should be 5 feet from the wall (measured from the base to the point directly below the support). Use the 'ladder leveling device' or a smartphone app (e.g., 'Ladder Safety' by OSHA) to verify the angle is 75-76 degrees.** (94% success)
   ```
   Use the 4:1 ratio: for every 4 feet of vertical height to the support point, place the base 1 foot away from the vertical line. Example: If the ladder rests against a wall at 20 feet height, the base should be 5 feet from the wall (measured from the base to the point directly below the support). Use the 'ladder leveling device' or a smartphone app (e.g., 'Ladder Safety' by OSHA) to verify the angle is 75-76 degrees.
   ```
2. **Perform the 'stand-off test': Stand facing the ladder with your toes touching the base. Extend your arms straight out. If your palms can touch the ladder's side rails at shoulder height, the angle is approximately correct (75 degrees). If you have to lean forward, the ladder is too steep; if you can touch above shoulder height, it's too shallow.** (88% success)
   ```
   Perform the 'stand-off test': Stand facing the ladder with your toes touching the base. Extend your arms straight out. If your palms can touch the ladder's side rails at shoulder height, the angle is approximately correct (75 degrees). If you have to lean forward, the ladder is too steep; if you can touch above shoulder height, it's too shallow.
   ```
3. **Use a ladder leveling device or stabilizer to ensure the ladder is at the correct angle and on stable ground. For uneven surfaces, use ladder levelers (adjustable feet) rather than stacking blocks or bricks. Example setup: 'Ladder base placed on concrete, levelers adjusted to compensate for 2-degree slope, base 5 ft from wall, ladder extended 3 ft above roof edge for safe access.'** (90% success)
   ```
   Use a ladder leveling device or stabilizer to ensure the ladder is at the correct angle and on stable ground. For uneven surfaces, use ladder levelers (adjustable feet) rather than stacking blocks or bricks. Example setup: 'Ladder base placed on concrete, levelers adjusted to compensate for 2-degree slope, base 5 ft from wall, ladder extended 3 ft above roof edge for safe access.'
   ```

## Dead Ends

- **** — A 60-degree angle places the base too close to the wall (ratio ~1.7:1 instead of 4:1), making the ladder unstable and prone to tipping; the ladder's feet may also slip due to reduced friction angle (90% fail)
- **** — This creates a steep angle (near vertical) that increases the risk of the ladder tipping sideways or the user leaning backward; also reduces the effective working height and increases the load on the ladder's side rails (85% fail)
- **** — The 4:1 ratio must be measured from the base to the vertical projection of the support point (where the ladder rests against the wall or roof), not the wall at ground level; if the wall is sloped or the ladder rests on a roof edge, this measurement is incorrect (75% fail)