Confined Spaces: General Industry vs Construction And How To Decide Which Rule Applies

A crew lowers a pump into a vault to clear a blockage at a treatment plant. Another crew opens a tank at a jobsite to weld a nozzle. The work looks similar. The rules are not. OSHA maintains two confined space standards, one for general industry and one for construction, and the line between them depends on the nature of the work. If you choose the wrong standard, you risk missing duties that were designed for the exact conditions you face. The way through the confusion is to anchor your decision in scope and roles. General industry 1910.146 governs permit required confined spaces in non construction settings and tells employers how to determine if a space is a permit space, how to control entry, how to train, and how to plan for rescue. Construction Subpart AA applies when the work is building, altering, or demolishing a structure and adds responsibilities tailored to dynamic, multi employer sites. The regulatory text and OSHA’s FAQ explain the differences, including the requirement in construction that a competent person identify confined spaces and determine which are permit spaces before work begins.

The decision point is not the label on the facility. It is the character of the job. If you are repairing or maintaining an existing system inside a plant where your activities do not change the structure, general industry is the default. If you are part of constructing, altering, or demolishing a structure, even inside an existing facility, the construction rule applies. The construction rule is blunt about the front end expectations. Before work, a competent person must identify each confined space where anyone you direct may work and must determine which of those spaces are permit spaces. The text then places specific obligations on entry employers, controlling contractors, and host employers so that communication about hazards and responsibilities is not left to chance. Those definitions matter where multiple trades share a site. If you are the controlling contractor, you are responsible for ensuring coordination, not just for your own entry team. The construction FAQ explains these duties in approachable language and points you back to the rule when you need exact wording.

Once you pick the correct standard, the fundamentals look familiar. You need a method to identify permit spaces. You need atmospheric testing with calibrated instruments and a clear record of acceptable entry conditions. You need isolation where hazards exist, from lockout of agitators to blanking and blinding lines that could introduce material into the space. You need attendants with defined duties, entrants who understand their right to leave when conditions change, and supervisors who know how to cancel and retain permits. You also need a rescue plan that is realistic. A fire department that is not trained or equipped for permit space rescue is not a plan. It is a hope dressed up as a phone call. The general industry text includes a path for alternate procedures when the only hazard is atmospheric and continuous forced air ventilation can maintain safe conditions. The rule spells out what documentation is required when you take that path. When hazards go beyond atmosphere, the full permit program applies.

Examples make the difference between theory and practice. If a contractor is building a new tank and cutting in manways, that is construction and Subpart AA controls. The controlling contractor must coordinate with entry employers so that one crew’s work does not create hazards for another. If a maintenance team is cleaning an existing tank in a food plant and replacing a mixer seal, that is general industry. The entry supervisor must ensure isolation of the mixer and any inlet lines, test the atmosphere, ventilate as needed, and prepare a permit that reflects the actual hazards. If a municipal crew is inspecting a manhole in a live system and using forced air ventilation to control the atmosphere, they may be able to use alternate procedures, but only if the hazards can be controlled by ventilation alone and only if the documentation requirements are met. The moment another hazard appears, like an engulfment risk from flow, the alternate path closes. Write these distinctions into your training. People learn from the jobs they recognize.

The biggest mistakes are judgment errors. Teams underestimate the speed at which oxygen can be displaced or the way a cleaning chemical reacts in a confined volume. They assume the work is too simple to justify full permits or that a confined space can be approached like any other area as long as someone glances at a meter. The rules exist because those assumptions have killed people. Treat every space as permit required until you can prove otherwise. If conditions change, stop and reassess. If you are straddling the line between construction and general industry because a job looks like maintenance inside a construction project, pick the more protective approach and document the reasons. No one has ever been cited for doing too much to keep a crew alive.

Sources and further reading: OSHA General Industry Confined Spaces at osha.gov/confined-spaces. OSHA Construction Confined Spaces at osha.gov/confined-spaces/construction. 29 CFR 1910.146 and 29 CFR 1926 Subpart AA. OSHA Construction Confined Spaces FAQ.