Confined Space Entry Checks
Permit space triggers, the air limits and the testing order, ventilation, the attendant and rescue crew, the isolation and lighting duties, and the permit content under OSHA 1926 subpart AA.
A space big enough to enter with a hazard to the air, the shape, or the engulfment needs a permit: test oxygen first, then flammables, then toxics, keep the blower running, post an attendant, and a rescue plan that does not rely on the crew going in.
How the math works
- Permit space test (1926.1211(a)): a permit-required confined space is big enough and configured well enough that an employee can enter, has a limited way out, and is not designed for continuous occupancy, with at least one of: a hazardous atmosphere, a material that can engulf, an inwardly converging wall or a sloping floor that pushes into a shape with no exit, a fan, a pump, a live electrical part, or any other recognized serious safety and health hazard.
- Air (1926.80(a)(1), 1926.55(c)(1), 1926.62): sewer entry rules set oxygen at 19.5 to 22 percent, methane under 10 percent of the lower flammable limit, hydrogen sulfide under 15 ppm, and carbon monoxide under 50 ppm; the general construction air limits set oxygen at 19.5 to 23.5 percent, flammables under 10 percent of the LFL, H2S under 20 ppm with a 10 ppm 8-hour average, and CO under 50 ppm with the 8-hour average at 35 ppm in general industry.
- Testing (1926.1203(f), 1926.1204(a)): test the atmosphere before entry, in the order oxygen, flammables, toxics, at the top, middle, and bottom of the space, with the space in the working condition, with a calibrated meter bump tested to a known span gas, and with continuous monitoring during the entry, with the reading, the time, and the meter on the permit.
- Crew roles (1926.1204, 1926.1205, 1926.1207, 1926.1209, 1926.1210): the entrant, the attendant outside with no other duty and with no entry, the entry supervisor who signs the permit and terminates it, the rescue service evaluated for capability and response time, non-entry retrieval for vertical entry, training on the hazards and the duties, and the annual practice rescue for an on-site team.
- Isolation and permit (1926.1203, 1926.1206, 1926.1208): isolate the space by lockout, blank, disconnect, gate, plug, and de-energize, post the permit at the entry, keep the permit valid for one entry and one shift, close the permit when the work is done, and re-test and re-evaluate on any change in the space, the work, the process, the weather, the flood, the surge, and the crew.
Is a manhole a confined space?
A manhole, a vault, a lift station pit, a digester, a tank, a silo, a pipe, and a booth are the classic permit-required confined spaces: an employee can enter bodily, the way out is limited by the shape, the space is not designed for continuous occupancy, and the air, the engulfment, the converging shape, the pump, the fan, and the live parts are the hazards (1926.1211(a)).
What gases do you test in a confined space?
Oxygen first (19.5 to 22 percent in a sewer, 19.5 to 23.5 percent generally), then flammables as a percentage of the lower flammable limit (methane is flammable from 5 percent by volume, so 10 percent of the LFL is 0.5 percent), then toxics, hydrogen sulfide under 15 ppm in a sewer entry and under 20 ppm generally, and carbon monoxide under 50 ppm. Test at three levels and monitor continuously (1926.1203(f), 1926.80(a)(1)).
Do I need a rescue plan for a vault entry?
Yes, and a 911 call is a rescue plan only when the service is evaluated for the response to a vault-like space with the access, the depth, and the capability, and the response time. A permit entry needs an attendant outside with no other duty, non-entry retrieval on a vertical entry, and a trained rescue team or an evaluated 911 service (1926.1204(e), 1926.1205, 1926.1210).