Enclosed spaces requirements

Entry must follow the permit-space requirements in Subpart AA if, after you take the precautions in 1926.953 and 1926.965, hazards still remain that either could endanger a worker's life or could interfere with escape. Under 1926.953(a), the standard explains that routine entries may use 1926.953 instead of the permit-space rules in 1926.1204 through 1926.1211 only when remaining hazards do not present a threat to life or impede escape. Refer to 1926.1204 and 1926.1211 for the permit-space program elements if a permit entry is required.

Vented vaults are excluded only if the employer determines the ventilation system is operating to protect employees before entry. 1926.953(a) explicitly says the section does not apply to vented vaults when the employer has made that determination. If you cannot make that determination, treat the space as an enclosed space and follow the requirements of 1926.953.

The employer must ensure safe work practices are used for entry, work in, and rescue from enclosed spaces. 1926.953(b) requires employers to implement procedures and controls that protect employees during routine enclosed-space entry and rescue.

Each employee who enters an enclosed space or serves as an attendant must be trained in the hazards, entry procedures, and rescue procedures. 1926.953(c) requires this training. In addition, where first-aid or CPR is relevant to the enclosed-space work, OSHA guidance notes that some confined-space standards require first-aid and CPR training for attendants and rescuers, so employers should confirm training needs for their specific work (see OSHA letter on CPR retraining at https://www.osha.gov/laws-regs/standardinterpretations/2023-02-23).

Employers must provide equipment that ensures the prompt and safe rescue of employees from the enclosed space. 1926.953(d) requires appropriate rescue gear (for example, retrieval systems, harnesses, retrieval lines, portable winches, or breathing apparatus) sized and maintained to the job hazards and the number of entrants.

Employers must check for pressure or temperature differences and evaluate whether a hazardous atmosphere might exist before removing a cover, and eliminate unsafe conditions before removal. 1926.953(e) directs employers to inspect foreseeable conditions (for example, check if a cover is hot or under pressure and loosen it gradually) and to consider site conditions that could cause oxygen deficiency or flammable atmospheres to develop.

When covers are removed, the opening must be promptly guarded by a railing, temporary cover, or other barrier that prevents accidental falls and keeps objects from entering the space. 1926.953(f) requires these physical protections at the opening immediately after cover removal.

No — employees may not enter an enclosed space that contains a hazardous atmosphere unless the entry complies with the permit-required confined space rules in Subpart AA. 1926.953(g) makes this prohibition explicit; if a hazardous atmosphere is present, follow 1926.1204 through 1926.1211 instead.

An attendant with first-aid training must be immediately available outside the enclosed space to assist if traffic patterns or other hazards exist at the opening used for entry, and the attendant may perform other nondistracting duties while keeping watch and ensuring safe entry/exit. 1926.953(h) requires this; the note to (h) also refers to 1926.965 for additional attendant requirements for manholes and vaults.

Test instruments used to monitor enclosed-space atmospheres must be kept in calibration and have a minimum accuracy of ±10 percent. 1926.953(i) requires proper calibration and specifies the accuracy requirement, so follow manufacturers' calibration schedules and keep records as part of your instrument maintenance program.

Before entry, the enclosed space atmosphere must be tested for oxygen deficiency with a direct-reading meter or similar instrument that provides immediate results. 1926.953(j) requires oxygen testing with a direct-reading device; testing may be unnecessary only if continuous forced-air ventilation is provided and the ventilation procedures ensure employees are not exposed to oxygen-deficient air.

You must test for oxygen first, and only after oxygen testing and any ventilation show sufficient oxygen should you test for flammable gases and vapors with a direct-reading instrument. 1926.953(j) and 1926.953(k) require this sequence because flammability sensors need adequate oxygen to give accurate readings.

If flammable gases/vapors are detected or oxygen deficiency is found, continuous forced-air ventilation must be used to maintain safe oxygen levels and prevent hazardous flammable concentrations; the ventilation must begin before entry and be directed to ventilate the immediate area where employees are present and continue until all employees leave. 1926.953(l) and 1926.953(m) require these ventilation controls and timing.

A continuous monitoring program may be used in place of ventilation only if flammable gases or vapors are initially detected at safe levels and the monitoring ensures there will be no increase above safe levels. 1926.953(l) allows monitoring in lieu of ventilation under those conditions; use the definition of "hazardous atmosphere" to decide whether a measured concentration is hazardous.

The air supply for forced-air ventilation must come from a clean source and must not increase hazards in the enclosed space. 1926.953(n) requires that intake air be free of contaminants and that ventilation equipment not introduce new hazards (for example, take intake away from exhaust or vehicle fumes).

If open flames are used, you must test for flammable gases and vapors immediately before using the flame and at least once per hour while the flame is in use, increasing frequency if conditions indicate hourly testing is insufficient. 1926.953(o) specifies the pre-use and hourly testing requirements and calls for more frequent checks when warranted by conditions.

Pre-entry oxygen testing is not required only if continuous forced-air ventilation is provided and the ventilation procedures ensure employees are not exposed to oxygen-deficient conditions. 1926.953(j) allows this exception, but the employer must have procedures that reliably maintain and demonstrate a safe oxygen level before permitting entry.

Direct-reading instruments must be kept in calibration and have a minimum accuracy of ±10 percent. 1926.953(i) requires that monitors be maintained to that accuracy standard, so follow the manufacturer's calibration schedule and document calibrations and bump tests before use.

For manholes and vaults, attendants must meet the basic availability and first-aid training requirements in 1926.953(h) and also follow the additional attendant and safety procedures specified in 1926.965. 1926.965 contains further requirements on traffic control, rescue access, and other protections unique to manholes and vault entries.

Forced-air ventilation must begin before entry and be maintained long enough for the employer to demonstrate a safe atmosphere exists before employees enter and must continue until all employees leave the enclosed space. 1926.953(m) requires ventilation to run for the duration of the entry.

Employers must use the standard's definition of "hazardous atmosphere" to decide if a measured concentration is hazardous and refer to applicable exposure limits and material data when evaluating results. 1926.953(l) notes this approach; consult relevant exposure limits and safety data sheets to determine whether a measured concentration constitutes a hazardous atmosphere.

The standard requires direct-reading meters or similar instruments that collect and immediately analyze samples without off-site evaluation for both oxygen and flammable-gas testing. 1926.953(j) and 1926.953(k) specify use of devices that provide immediate, on-site readings so you can make timely entry decisions.

The employer is responsible for assessing hazards of enclosed-space work and ensuring appropriate safe work practices and PPE are selected and provided. 1926.953(b) assigns the duty to the employer; OSHA's letter on PPE hazard assessment (https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28) emphasizes that employers must assess the workplace to determine hazards and document PPE requirements where PPE will be required.