Permit Required Confined Spaces - 1910.146 - Frequently Asked Questions

Navigating OSHA’s Permit-Required Confined Space (PRCS) standards can be challenging. Below are some commonly asked questions to help employers and workers understand the requirements and their application under 29 CFR 1910.146.

OSHA issued the 29 CFR 1910.146 standard for Permit-Required Confined Spaces on January 14, 1993, with an effective date of April 15, 1993. This regulation was developed to address the significant hazards associated with confined spaces, which had led to numerous fatalities and injuries in general industry. By establishing clear guidelines for identifying, assessing, and controlling confined space hazards, the standard aims to protect workers from risks such as hazardous atmospheres, engulfment, and entrapment.

Scope and Application


1. Does the PRCS standard only apply to manufacturing operations?
No. The standard applies to all general industry workplaces, including agriculture, manufacturing, transportation, utilities, retail, healthcare, and even museums or botanical gardens.


2. Are agricultural operations exempt from PRCS requirements?
Yes, operations under Standard Industrial Classification (SIC) codes related to crop and livestock production (Major Groups 01 and 02) are exempt. Other sectors within agriculture are reviewed on a case-by-case basis.


3. What about the telecommunications industry?
Telecommunications employers must evaluate their workplaces for permit-required confined spaces. While some manholes or vaults may already be addressed by 29 CFR 1910.268(o), additional hazards might require compliance with 1910.146.


4. How does PRCS apply to shipyards, marine terminals, and longshoring?
Shipyards and marine terminals are not covered by 1910.146 but instead have their own standards under 29 CFR 1915 and 29 CFR 1917/1918.

5. Does PRCS apply to electric power facilities?
Yes. While electric power facilities follow 29 CFR 1910.269 for specific enclosed spaces, PRCS applies to confined spaces not covered under 1910.269.

Definitions and Classifications

6. What qualifies as “limited or restricted means of egress”?
Stairs, ladders, or access points that hinder escape during an emergency are considered restricted. Even doors may qualify if the surrounding environment complicates rapid exit.


7. Can spaces originally designed for continuous human occupancy become confined spaces?
Yes. If changes introduce hazards or make the space unfit for continuous occupancy, it may need reclassification.


8. Does water alone make a space permit-required?
No. The presence of water must pose a life-threatening risk or hinder escape to classify the space as permit-required.


9. What constitutes a hazardous atmosphere under PRCS?
Hazardous atmospheres include oxygen levels below 19.5% or above 23.5%, flammable gases exceeding 10% of their lower flammable limit (LFL), and toxic contaminants at levels that impair escape or cause acute illness.

Evaluating and Managing Spaces

10. Do employers have to survey every confined space physically?
Not necessarily. Employers can use existing records and knowledge if sufficient to evaluate hazards. However, spaces suspected of significant hazards must undergo detailed assessment.


11. How should employers inform employees about permit spaces?
Using warning signs is the most common approach, but alternative methods like training may be acceptable if they effectively prevent unauthorized entry.


12. What are “effective measures” to prevent entry into a permit space?
Employers can use locks, barriers, danger signs, and training to ensure workers do not enter permit spaces unintentionally.


13. How long can a space remain reclassified as non-permit?
A space remains non-permit as long as all hazards are eliminated. Documentation of hazard elimination must be maintained for the duration of the work.

 

Monitoring and Testing

14. What does “continuous monitoring” mean?
Continuous monitoring involves ongoing atmospheric testing to ensure safe conditions throughout an entry. Area monitors can be used for small groups working closely together.


15. How frequently should testing occur?
Testing frequency depends on factors like initial test results, the regularity of entry, and the space’s uniformity. Employers must document and justify their chosen frequency.


16. What qualifies as a “calibrated” direct-reading instrument?
Calibration must follow the manufacturer’s instructions. Employers should keep records to verify compliance.

 

Roles and Responsiblities

17. Can one person serve as both an Entry Supervisor and Authorized Entrant?
Yes, provided they are adequately trained and their dual responsibilities do not conflict.

18. How far can an attendant be from monitored spaces?
There is no specific distance requirement, but the attendant must effectively perform all duties without compromising entrant safety.


19. What are the employer’s responsibilities for multi-employer entries?
Employers must coordinate entry procedures, communicate hazards, and establish clear roles. Host employers must provide information about the space, and contractors must obtain and use this information.

 

Rescue and Emergency Services

20. Do off-site rescue services need a full PRCS program?
No, but they must have specific rescue plans, trained personnel, and appropriate equipment for the spaces they cover.


21. Is non-entry rescue required for horizontal spaces?
Yes, when feasible. Lifelines or lanyards may pose challenges in horizontal spaces, but non-entry rescue remains the preferred method.


22. Can a rescuer use a supplied-air respirator with an SCBA in IDLH atmospheres?
Yes, if the setup meets ANSI standards and specific conditions, such as independent air sources and immediate withdrawal policies, are followed. OSHA considers this a de minimis violation.