OSHA scaffolds (Subpart L) for the CHST
Scaffolds put a workplace in the air, so they combine falls, struck-by and collapse in one structure. Subpart L (29 CFR 1926.450 to 1926.454) covers them in detail. The CHST blueprint lists working at heights, material handling and struck-by hazards in Domain 1. This guide gives the section map and the points the exam favors, in our own words.
Check anything you rely on against your own licensed code book and the edition your AHJ enforces.
Where Subpart L sits in the blueprint
Domain 1 is 36.6% of the CHST. Scaffold questions usually test who decides what (the competent person) and which number applies (10 feet, the capacity factor, power line clearance), rather than the names of parts.
The sections to know
- 1926.450 covers scope, application and definitions.
- 1926.451 holds the general requirements. Its key points: a scaffold and its components must support their own weight plus at least four times the maximum intended load. Platforms are fully planked, with the width and gap rules in paragraph (b). Fall protection is required above 10 feet, by guardrails or a personal fall arrest system depending on the scaffold type, in paragraph (g). Safe access is required (paragraph (e)). Falling object protection is required where something could fall on people below (paragraph (h)).
- 1926.451(f) sets the use rules: a competent person inspects the scaffold before each work shift and after anything that could affect its structure, and scaffolds are not loaded beyond capacity or moved with workers on them. Clearance from energized power lines is a table in 1926.451(f)(6), and the figures grow with voltage.
- 1926.452 gives extra rules by scaffold type: pole, tube and coupler, fabricated frame, suspension, mobile and others.
- 1926.453 covers aerial lifts, which the exam may mix in with scaffold questions.
- 1926.454 requires training: workers using scaffolds must be trained to recognize the hazards, and those who erect or dismantle them need training in the procedures.
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Emergency Preparedness, Incident Investigation, and Response
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Who does what
A competent person oversees erection, moving, alteration and dismantling, with a qualified person's design where the rule requires one. Users do not alter the scaffold. A competent person also inspects before every shift, and that is a repeated duty, not a one-time check at erection.
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Common mix-ups
- 10 feet is the scaffold trigger. The general fall trigger is 6 feet. Match the number to the work.
- Capacity is a safety factor. The structure must carry a multiple of the load, so a scaffold at its rated load is not at its breaking point.
- Inspect before each shift. One inspection at the start of the job is not enough.
- Guardrails depend on type. Some scaffolds allow a personal fall arrest system in place of rails: read the paragraph for the type in the question.
How to practice
Pick three scaffold types and write the fall protection rule, access rule and inspection rule for each. Work questions that give a height and a scaffold type and ask what protection is needed.
Work out the tie heights and the 4:1 ratio with the scaffold tie calculator.
Related guides: fall protection (Subpart M), electrical (Subpart K) and ladders (Subpart X).
Practice it
Take the free 10-question check. It covers the four CHST domains, needs no signup and explains every answer, so you see whether this subpart is a weak spot. The CHST study guide shows where it fits in a six-week plan.
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Sources
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- 29 CFR 1926 Subpart L, Scaffolds, OSHA.
- CHST Examination Blueprint (CHST5, V.2022.04.12), Board of Certified Safety Professionals.
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