What Are The Three Types of OSHA Confined Spaces?

The three definitions of OSHA confined spaces include permit confined space, general industry, and construction. If you are doing construction work - such as building a new structure or upgrading an old one - then you must follow the Occupational Safety and Health Administration’s (OSHA) rules on construction confined spaces and general industry confined spaces.  

It used to be that the only requirement for confined spaces in construction was training. But OSHA concluded this was inadequate as injuries and fatalities continued to occur. So, in 2015 OSHA issued a new standard for construction work in confined spaces. This new standard replaces OSHA’s one training requirement for confined space work with a comprehensive standard that includes a permit program designed to protect employees from exposure to many hazards associated with work in confined spaces, including atmospheric and physical hazards.

Let’s take a look at the three definitions of OSHA confined spaces and break down the details on the updated standards.

Construction - Confined Space

The construction confined space provisions on the OSHA website describe confined or enclosed spaces as "any space having a limited means of egress, which is subject to the accumulation of toxic or flammable contaminants or has an oxygen-deficient atmosphere."

There is also a section that provides examples of confined or enclosed spaces. They include, but are not limited to:

Also making the list are open-top spaces that are more than 4 feet in depth. These include: 

  • Pits
  • Tubs
  • Vaults 
  • Vessels

OSHA regulators say that the size, configuration, and potential hazards would determine if they’re considered a confined space. 

Standards OSHA Added in 2015 For Construction

In 2015, when OSHA decided that requiring training wasn’t enough, they developed five key differences from the construction rule and several areas where OSHA has clarified existing requirements. The five new requirements also provide more detailed provisions, including:

  1. Coordinated activities when there are multiple employers at the worksite. 
    1. An example would be a generator running near the entrance of a confined space causing a buildup of carbon monoxide within the space.
  2. Requiring a competent person to evaluate the worksite and identify confined spaces, including permit spaces.
  3. Requiring continuous atmospheric monitoring whenever possible. 
  4. Requiring continuous monitoring of engulfment hazards. 

OSHA also added to the definitions of several terms tied to the construction rule, like "entry employer." This term describes the employer who directs workers to enter a space. They also added "entry rescue" to clarify the differences in the types of rescue employers can use.

General Industry - Confined Space

According to OSHA regulators, a confined space in General Industry standards is a space that:

  1. It is large enough and configured so that an employee can enter and perform assigned work.
  2. It’s a space with limited or restricted means for entry or exit like utility vaults, and pits.
  3. It is not designed for continuous employee occupancy.

Standards OSHA Added in 2015 For General Industry

The requirements OSHA added to the General Industry provisions include:

  1. Employers directing workers into a confined space without using a complete permit system must eliminate any hazards or use isolation methods such as lockout/tag out.
  2. Employers who are relying on local emergency services, in the event of an accident, must get advanced notice IF there’s a period of time emergency services cannot respond (like during another emergency or training)  
  3. Requiring employers to provide training in a language and vocabulary that the worker understands.

Anyone who goes into a confined space must also be trained and maintain contact at all times with a trained attendant either visually, via phone, or by two-way radio.

Permit Confined Space

The terms "permit-required confined space" and "permit space" refer to spaces that meet OSHA's definition of a "confined space" and contain health or safety hazards. 

For this reason, OSHA requires workers to have a permit to enter these spaces. A permit-required confined space has one or more of these characteristics:

  • Contains or has the potential to contain a hazardous atmosphere.
  • Contains a material with the potential to engulf someone who enters the space;
  • It has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls, or by a floor that slopes downward and tapers to a smaller cross-section.
  • Contains any other recognized serious safety or health hazards.

Employers must take steps to protect workers only if they work in a permit space. In addition, they must take effective steps to prevent workers they control from entering the space unless the workers are authorized to enter. 

Confined Spaces and Backflow Preventers

Despite all of the rules and regulations regarding confined spaces, there are still design engineers and water purveyors who continue to allow and design backflow preventers in utility vaults. This is the last place you’d want to put a backflow preventer. That’s why we’re asking you to “Think Outside The Vault.” On this page, you’ll find a video and an infographic demonstrating the dangers of installing backflow preventers inside utility vaults.




Does OSHA Require Annual Confined Space Training?

No they do not. However, intense training and confined space knowledge is required.

What is Considered a Confined Space by OSHA?

Meter vaults, backflow pits and any subterranean vault.


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