Manholes, vaults, crawl spaces and tanks can hold hazards nobody sees. Here is how contractors control confined-space entry.
In this article
What a confined space is
A confined space is large enough for a worker to enter, has limited means of entry or exit and is not designed for continuous occupancy. On construction sites, that includes manholes, crawl spaces, tanks, vaults, pits, attics and some ductwork. OSHA has a specific standard for confined spaces in construction.
Permit-required spaces
Some confined spaces have serious hazards, such as a dangerous atmosphere, engulfment risk or a layout that could trap a worker. These are permit-required confined spaces and need a written program, a permit and specific procedures before entry.
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Common hazards
- Low oxygen or toxic gases like carbon monoxide and hydrogen sulfide.
- Flammable atmospheres.
- Engulfment by water, soil or materials.
- Heat and limited ventilation.
Evaluate the site
Before work begins, a competent person should identify the confined spaces on the site and decide which require permits. Spaces can change during a project, so evaluation is not a one-time task.
Test the air
Test the atmosphere before entry and monitor it during work. Many deadly gases cannot be seen or smelled.
Entrant, attendant and supervisor
Permit spaces require defined roles: the entrant who goes in, the attendant who stays outside and monitors and the entry supervisor who authorizes the work.
Plan the rescue first
Many confined-space deaths are would-be rescuers who rushed in without protection. Have a rescue plan and equipment in place before anyone enters, and confirm whether local emergency services can respond in time.
Coordinate between employers
On multi-employer sites, the GC and subs must share information about confined spaces, hazards and entry procedures.
Train everyone involved
Workers, attendants and supervisors need training specific to their roles before the first entry.
Document the rescue plan
Write down the rescue method, the equipment, who is trained and how long a response will take. If you rely on an outside rescue service, confirm in advance that they can reach the site and handle that type of space.
Mark the spaces
Inform workers about permit spaces with signs or other effective means, so nobody enters a manhole or vault by accident.
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Frequently asked questions
What is a permit-required confined space?
A confined space with serious hazards, such as a dangerous atmosphere, engulfment risk or a layout that could trap a worker. It requires a written program, a permit and specific entry procedures.