OSHA defines confined spaces as those with configurations which hinder activities of employees who must enter, work in and exit places that have limited and restricted means for entry or exit, and are not designed for continuous employee occupancy.  These can include:

  • storage bins
  • manholes
  • pits
  • silos
  • process vessels
  • pipelines
  • underground vaults
  • sewers
  • wells
  • tanks

One or more of the potential hazards of working in Permit-Required Confined Spaces can be a hazardous atmosphere to engulf the entrant, walls that converge inward, or floors sloping downward and tapering into smaller area which could possibly trap or asphyxiate the person, unguarded machinery, exposed live wires, or heat stress.

To prevent accidents, companies should:

  • Train employees thoroughly;
  • Post proper signs on location;
  • Always assume that hazards are present;
  • Follow proper lockout/tagout procedures;
  • Ensure adequate ventilation for employees;
  • Furnish non-sparking tools;
  • Provide and ensure required PPE is used at all times;
  • Monitor continuously while work is being performed;
  • Have rescuers on site and trained for any emergency.

It is estimated that over one and one-half million workers enter confined spaces annually.
Most accidents can be prevented by properly educating the persons who do this work and ensuring that they are adequately supervised at all times.


  1. Two things that are often overlooked in the OSHA CSE standard is the ability to reclassify a space as non-permit required if you can elimate all hazards through means of lockout/tagout, and also enter spaces with only atmospheric hazards via OSHA’s alternate entry procedures if they can be controlled through continuous forced air ventilation alone (like what you see the phone companies use at their vaults sometimes. These two means of entry are not suitable (or even allowed) unless your space meets certain qualifications. More infomation or training assistance is available at .

  2. Two things that cannot be overlooked in the OSHA CSE standard are:
    1) the ability to reclassify some spaces (with only hazards like mechanical devices, electrical . . .) as non-permit required by eliminating the hazard(s) completly by means such as lockout, and,
    2) the ability to enter under OSHA’s alternate entry procedures by controling atmospheric hazards via continuous forced ventilation, like you see the phone company do at their vaults sometimes. These two procedures make certain elements of confined space entry SO much easier (like no rescue required . . .), but certification of steps taken is still necessary (similar to a permit, but not as onerous). There is a website ( ) that offers links and training on this topic.

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