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Free course · Beginner · 3 h 52 min · v1.0

Confined Space Awareness

Permit-required confined spaces under 29 CFR 1910.146 and 1926 Subpart AA — free and self-paced

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This course is step 2 of 4 in the Excavation Crew — Learning Path, which puts the free courses on this site in a reading order.
Not OSHA-authorized training. This free course is a study aid. It does not satisfy any OSHA or regulatory training requirement and no certificate or card is issued. Your employer's training program comes first.

A confined space kills quietly and it kills twice. The first worker goes down without a sound, because an oxygen-deficient atmosphere gives no warning; the second is the coworker who leans in to help. This free, self-paced course walks through 29 CFR 1910.146 and 29 CFR 1926 Subpart AA the way a crew meets them: what makes a space confined, what makes it permit-required, where a bad atmosphere comes from and why oxygen is always tested first, what isolation actually means, what the entrant, the attendant and the entry supervisor each owe the entry, and why a written rescue plan is the difference between one casualty and two. Every requirement is quoted with the paragraph it comes from, and every incident is a real OSHA case file.

What you will be able to do

  • Tell a confined space from a permit-required confined space using the definitions, not the shape of the opening
  • Recognize the five causes of a hazardous atmosphere and explain why oxygen is always tested first
  • Say what isolation, purging, inerting and reclassification each mean, and what none of them mean
  • State what the authorized entrant, the attendant and the entry supervisor must each do, and what they may never do
  • Judge whether a rescue arrangement is a plan or a phone number, and why non-entry rescue comes first

Course outline

Part 1

Confined space, or permit-required confined space?

The three conditions that make a space confined, the four characteristics that make it permit-required, how the general industry and construction standards differ, and the three lawful ways to go in.

  1. 1.1 What a confined space actually is13 min
  2. 1.2 The four characteristics that make it permit-required12 min
  3. 1.3 1910.146 and 1926 Subpart AA, side by side13 min
  4. 1.4 The three lawful ways in13 min
  5. Part 1 quiz5 questions
Part 2

Hazardous atmospheres and the order of measurement

The five causes of a hazardous atmosphere, where a bad atmosphere comes from, how the air is actually tested and why oxygen goes first, and what ventilation and monitoring can and cannot do.

  1. 2.1 The five causes of a hazardous atmosphere12 min
  2. 2.2 Where the bad air comes from13 min
  3. 2.3 Testing: instruments, response time and the order13 min
  4. 2.4 Ventilation, monitoring and the prohibited condition12 min
  5. Part 2 quiz5 questions
Part 3

Physical hazards, isolation and the three roles

Engulfment and the hazards that have nothing to do with the air, what isolation means and what it does not, the duties of the entrant, the attendant and the entry supervisor, and the permit itself.

  1. 3.1 The hazards that have nothing to do with the air12 min
  2. 3.2 Isolation: blanking, blinding, double block and bleed12 min
  3. 3.3 Entrant, attendant, entry supervisor13 min
  4. 3.4 The permit: fifteen elements and a cancellation13 min
  5. Part 3 quiz5 questions
Part 4

Rescue, and why the rescuer becomes the second victim

What actually happens in a confined space emergency, non-entry rescue and its hardware, how to choose and evaluate a rescue service, and what keeps a program honest between entries.

  1. 4.1 The second victim12 min
  2. 4.2 Non-entry rescue comes first12 min
  3. 4.3 Choosing a rescue service, and 911 is not one13 min
  4. 4.4 Training, contractors and keeping the program honest12 min
  5. Part 4 quiz5 questions
Final exam
20 questions · about 20 minutes
Go to the exam

Who it's for: Maintenance and utility crews, tank and vessel cleaners, municipal water and sewer workers, plant operators, construction crews working in vaults, manholes and pits, and the supervisors who sign their permits.

Frequently asked questions

No. Entry is allowed only under an employer's written permit space program, in a role your employer has designated you for, after the training 1910.146(g) or 1926.1207 requires — training that has to cover your specific spaces, your specific hazards and your assigned duties, and that has to be recorded with your name and the dates. This course is awareness: it explains the standards so you understand what your employer's program is doing and why. It does not authorize anything.

No. SteelToeTools is not affiliated with, endorsed by, or authorized by OSHA or the U.S. Department of Labor. We quote the public text of the standards and link to them so you can check every statement yourself.

No. Nothing is issued for completing this course or its exam — no card and no document of any kind. It is a free study aid, not OSHA-authorized training, and it does not satisfy any regulatory training requirement.

Both, side by side. 1910.146 is the general industry standard and the older of the two; 1926 Subpart AA has applied to construction work since 2015 and differs in ways that matter — a competent person identifies the spaces, continuous atmospheric monitoring is the default, an early-warning system is required for non-isolated engulfment hazards, and duties are split between the host employer, the controlling contractor and each entry employer. Part 1, Chapter 3 puts them next to each other, and every later chapter says which standard a requirement comes from.

About 3 hours 52 minutes: sixteen chapters of 12 to 13 minutes, four 5-question part quizzes, and a 20-question final exam. Your progress is kept in your own browser, so you can stop and come back.

Not as trenches. 1926.1201(b)(1) says the confined spaces standard does not apply to construction work regulated by 1926 Subpart P, which is the excavation standard — and Subpart P has its own atmospheric rules at 1926.651(g). What Subpart AA does cover is the manhole, vault, pipe or wet well that gets opened inside the excavation: work in that space is not work regulated by Subpart P, and 1926.1201(c) adds that where another OSHA standard addresses a confined space hazard, the employer complies with both. Part 3 covers where the two meet.

Because the case files do. 1910.146(d)(9) requires procedures for summoning rescue, for rescuing entrants, for treating them, and for preventing unauthorized personnel from attempting a rescue — and it is that last duty that the incidents keep breaching. Part 4 is built on OSHA Accident Search Summary Nr 146892.015: a worker fell into a vault, a coworker who saw it went in after him, and both died of asphyxiation.

Sources & references

Content checked against these sources — last reviewed August 28, 2026.

Not OSHA-authorized training. SteelToeTools is not affiliated with, endorsed by, or authorized by OSHA or the U.S. Department of Labor. This free educational content does not satisfy any OSHA or other regulatory training requirement, and no card, certificate, or credential is issued. Only OSHA-authorized trainers can deliver OSHA Outreach Training (10-Hour and 30-Hour) and issue DOL cards. Always follow your employer's training program and applicable federal, state, and local requirements.

By — Editorial team of SteelToeTools.com (published by LSEA SAS) Updated v1.0