Confined space
A space big enough to enter and work in, with limited ways in or out, that isn't designed for people to stay in.
Definition, in the source's words
29 CFR 1910.146(b)(opens ecfr.gov in a new tab)“Confined space means a space that: (1) Is large enough and so configured that an employee can bodily enter and perform assigned work; and (2) Has limited or restricted means for entry or exit (for example, tanks, vessels, silos, storage bins, hoppers, vaults, and pits are spaces that may have limited means of entry.); and (3) Is not designed for continuous employee occupancy.”
What it means
All three conditions must be true. A space that meets them is a confined space; whether it needs a permit depends on its hazards (see permit-required confined space).
Construction work is covered by 29 CFR 1926 Subpart AA, which uses a closely similar definition.
Example
A 20,000-gallon storage tank with one 24-inch manhole: a worker can climb in and clean it (1), the manhole restricts entry and exit (2), and nobody works in it day to day (3). It's a confined space. A boiler room with a normal door fails (2) and (3), so it isn't.
Where it appears on the exam
ASP: ASP11 Domain 2, Safety Programs and Concepts
Practice: Permit-Required Confined Spaces
CSP: CSP11 Domain 1, Advanced Application of Safety Principles
Practice: Confined Spaces and Lockout/Tagout
CHST: CHST5 Domain 1, Hazard and Risk Identification and Control
Practice: Confined Spaces in Construction
Questions
- Is every confined space a permit space?
- No. A confined space becomes a permit-required confined space only if it has one or more of the four hazard characteristics in 1910.146(b), such as a potential hazardous atmosphere or engulfment.
Related
- Permit-required confined space
- Attendant (confined space)
- Entry supervisor
- Hazardous atmosphere
- Regulation: 29 CFR 1910.146
Checked 2026-10-16. Spot a problem? Email hello@passcited.com.