Confined Space

California's Department of Industrial Relations General Industry Safety Orders Article 108, Confined Spaces (based on the federal OSHA standard, 29 CFR 1910.146) defines a confined space as:

  • a space that is large enough and so configured to permit entry and work
  • a space that is not designed for continuous human occupancy
  • a space that by design has limited or restricted means for entry and exit 

When an area has all three of the above characteristics, it is considered to be a confined space that is subject to regulation by the standard. It is important to note that failure to satisfy one of the above criteria means that it is not a confined space according to the definition, and therefore not subject to the standard. However, there are documented circumstances that have resulted in injury or death, when not all of the above conditions have been satisfied. These incidents could have been prevented if there was a better awareness of confined space hazards. Do not be overly constrained by the technicalities of the definition; if it looks like a confined space, treat it like one until the hazards have been fully assessed and the potential for risk has been determined.

Since the essence of the regulation is embodied in the requirements for Permit Required Confined Spaces (PRCS), let's review what makes a confined space a PRCS. A PRCS is a space that meets the definition of a confined space above, and has one or more of the following hazardous characteristics:

  • contains or has the potential to contain a hazardous atmosphere (oxygen, flammability, and toxicity)
  • contains a liquid or finely-divided solid material, that could surround or engulf (frequently associated with loose material, like grains)
  • has an internal shape that could cause entrapment (caused by inwardly sloping walls)
  • contains other recognized serious safety or health hazards (such as temperature extremes, mechanical, electrical)

The regulation applies to all permit-required confined spaces. Examples include tanks, vats, silos, storage bins, process or reactor vessels, vaults, sewers and pits, machinery enclosures, boilers, and rail tank cars. Both federal and California state rules require that an employer prepare a written confined space safety program that addresses the precautions to be taken for entering and working in permit-required confined spaces.

The written PRCS program contains a number of key elements that must be addressed, which are summarized in the following list:

  • identify and classify all spaces (permit or non-permit)
  • take steps to prevent unauthorized entry and notify employees that spaces exist
  • develop procedures and practices for safe entry activities, including control measures (such as isolation, ventilation, and periodic atmospheric testing for changing conditions)
  • perform atmospheric monitoring to determine if acceptable entry conditions exist
  • establish key personnel to implement program - entrant, attendant, entry supervisor, atmospheric tester, and emergency response - and define responsibilities and training requirements
  • conduct training to ensure all workers have understanding, knowledge, and skills
  • establish and implement a permit system for entry and work that includes provisions for canceling the permit and returning a space to service
  • develop procedures that address safety of contractor personnel when involved in confined space situations
  • establish procedures for rescue and emergency services
  • provide specialized equipment such as atmospheric monitoring, ventilation, PPE, lighting, communication, and emergency/rescue equipment 

The UCSC PRCS program addresses these elements and must be followed by any employee entering a confined space. If you have any questions about an area you are required to enter, notify your supervisor or contact EH&S for an evaluation of the hazards of the space.

UCSC Confined Space Documents

Confined Space Policy

Non-permit-required confined space entry form (Word format)