OSHA Confined Spaces FAQ

Posted on 10/7/2014 by James Griffin

In many industries, employees commonly perform work inside of “confined spaces.” To protect these employees, OSHA’s General Industry Standard includes specific rules employers must follow, including permitting requirements for certain confined spaces.
The Permit-Required Confined Spaces (PRCS) Standard at 29 CFR 1910.146 is one of several of OSHA’s General Industry Standards governing General Environmental Controls under 29 CFR 1910, Subpart J.
Q. What is a confined space?
A. A confined space is a space that is:
  1. Large enough that an employee can enter it and perform work, but
  2. Not designed for continuous employee occupancy, and
  3. Has limited or restricted means for entry or exit.
[29 CFR 1910.146(b)]
Examples of confined spaces include tanks, hoppers, and other large means of containment, as well as structures like grain silos, vaults, and pits.
Q. What is a permit-required confined space?
A. A permit-required confined space is a confined space that has one or more of the following characteristics:
  1. It contains, or has the potential to contain, a hazardous atmosphere (e.g., toxic gas in a sewer or carbon dioxide buildup in a space with poor ventilation);
  2. It contains a material that has the potential for engulfing a person who enters it (e.g., grain in a silo);
  3. It has an internal configuration with inwardly converging walls or downward sloping floors with small cross-sections that could trap or asphyxiate a person who enters the space; or
  4. It contains any other recognized serious safety or health hazard (e.g., exposed electrical elements or moving machinery)
Q. Why is it called a permit-required confined space?
A. A confined space with a hazardous atmosphere, or other serious hazard, is called a permit-required confined space because no employee is allowed to enter that space without a written authorization. This document is called an “entry permit.”
Q. What is “entry” in this context?
A. An employee “enters” a confined space any time any portion of his or her anatomy breaks the plane of an opening into the confined space. [29 CFR 1910.146(b)] For instance, just sticking an arm into a confined space would be considered “entry.”
Q. What’s in an entry permit?
A. Each time one or more employees enter a permit-required confined space to do work, the employer must issue them an entry permit. Each entry permit must identify:
Administrative information-  
  1. The space to be entered;
  2. The purpose of the entry;
  3. The date and authorized duration of the entry;
  4. The persons who are authorized to enter the space;
  5. The persons who will attend the entry from outside the space;
  6. The name and signature of the person supervising the entry;
Hazard information-
Employee working in confined space
  1. The hazards of the space;
  2. The measures used to isolate the space and eliminate or control the hazards of the space (lockout/tagout for mechanical hazards, ventilation/purging/
  3. inerting/flushing hazardous atmospheres, etc.);
  4. The conditions of acceptable entry;
  5. The results of initial and periodic testing, accompanied by the names/initials of testers and date of testing;
Equipment and Procedures-
  1. The identity and means of contacting emergency services, should they be required;
  2. The procedures used by authorized entrants and attendants to communicate during the entry;
  3. Any equipment used by authorized entrants, attendants, the entry supervisor, or others to comply with the requirements of the PRCS Standard;
Miscellaneous Information-
  1. Any other information necessary to ensure employee safety; and
  2. Any additional permits that may be required (i.e., for “hot work”).
Q. What else is required in the workplace?
A. In a workplace where employees enter into a PRCS, the employer must create and file a written permit each time employees enter the space. The requirements above address individual entry permits only. [29 CFR 1910.146(f)]
In addition to the individual entry permit, the employer must consult with employees and establish a comprehensive written program for controlling and protecting workers from permit space hazards (Permit Space Program). Other required elements include a written procedure for preparing, issuing, and closing entry permits; certified written training programs for authorized entrants, their outside attendants, and entry supervisors; and equipping and training rescue teams. [29 CFR 1910.146(c)(4), 1910.146(g)–(l))]
Lastly, if any PRCSs exist in the workplace—even if employees never enter them&mdashthe employer must post signs informing employees and prevent entry into the space. [29 CFR 1910.146(c)(2)–(3)]
Protecting Employees Under OSHA’s General Industry Standard
Lion Technology offers convenient, 24/7 online training to help employers and workers meet OSHA’s training and awareness requirements. A full list of online courses is available now at For more information on how OSHA regulates specific workplace hazards, including confined spaces, see the complete OSHA Training FAQ at

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