Confined Space Entry Permit
The permit is not paperwork you file after the fact. Under 1926.1204 it is the document that authorises the entry, and it has to be complete and signed by the entry supervisor before anyone breaks the plane of the opening.
A permit is valid for one entry operation and is cancelled when the operation ends. Atmospheric readings are recorded, not remembered \u2014 1926.1204 requires the permit to document the tests performed.
Space and entry
Test in this order, and write down the numbers
Oxygen, then flammables, then toxics. The order is not a preference — a combustible-gas sensor gives a meaningless reading in an oxygen-deficient atmosphere, so the oxygen number has to come first or the flammable number cannot be trusted.
| Reading | Acceptable entry condition | Where it goes |
|---|---|---|
| Oxygen | 19.5% – 23.5% | Permit, initial and periodic |
| Flammable / combustible | < 10% LFL | Permit, initial and periodic |
| Toxic (e.g. CO, H₂S) | below the PEL for the substance | Permit, initial and periodic |
Acceptable entry conditions are defined per space by the entry employer under 29 CFR 1926.1204(c) — read 2026-09-04. Confirm the toxic limit against the substance’s own PEL.
Every reading gets a time and a set of initials. A permit with a single column of numbers taken at 07:00 for an eight-hour entry is not a record of continuous monitoring.
Three roles, and the one that cannot leave
The entry supervisor signs the permit and terminates it. The authorised entrant does the work. The attendant stays outside — and the standard is explicit that the attendant may be assigned to more than one permit space only if the duties under 1926.1209 can still be performed for each of them, and the permit program says how the attendant answers an emergency in one space without abandoning the others.
Danger
Rescue is arranged before entry, not called after
1926.1204(i) requires the entry employer to develop and implement procedures for summoning rescue and emergency services and for rescuing entrants. The service has to be able to reach the space in time to be useful, and non-entry retrieval is required whenever it does not increase the overall risk.
Write the rescue service, the phone number and the response time on the permit. “911” on its own is a line in a box, not a procedure — the local fire department may or may not have a confined-space team, and finding out at the moment of an entrant collapse is too late.
When you can skip the permit — and when you cannot
Two escapes exist and both are narrow. Alternate procedures under 1926.1203(e) apply only when the sole hazard is atmospheric and continuous forced-air ventilation alone keeps the space safe for entry. Reclassification under 1926.1203(g) applies only when every hazard in the space has actually been eliminated — not controlled, eliminated.
And if a hazard arises inside a reclassified space, every employee must exit, and the space is re-evaluated and reclassified as a permit space. The reasoning behind each route is worked through in permit-required confined spaces.
Sources, with the date each was read
- 29 CFR 1926.1204 — Permit-required confined space program (OSHA)read 2026-09-04
- 29 CFR 1926.1203 — General requirements, Subpart AA (OSHA)read 2026-09-04
- 29 CFR 1926.32(f) — Definition of competent person (OSHA)read 2026-09-04