Only the wisest of Safety Gurus might be able to correctly designate which of the following are permit-required confined spaces:
1) Trench or Pit (greater or equal to 4' depth)
2) Bulk Trailer (being serviced or repaired)
3) Residential Crawl Space (Attic or Basement)
4) Manure Pit
Confined Space Crash Course:
According to OSHA, a confined space has limited or restricted means for entry or exit and is not designed for continuous occupancy. And a permit-required confined space has one or more of the following characteristics: contains or has the potential to contain a hazardous atmosphere; contains material that has the potential to engulf an entrant; has walls that converge inward or floors that slope downward and taper into a smaller area which could trap or asphyxiate an entrant; or contains any other recognized safety or health hazard, such as unguarded machinery, exposed live wires, or heat stress.
1) Treat as Permit-Required. Section 1926.1201 of OSHA regulation states that trenches and other excavations do not fall within the regulation for permit-required confined spaces. However according to many safety experts, if working in any trench with a depth equal to or greater than 4 feet should follow the same precautions and procedures as working if working within a permit required confined space. So it may be best to err on the side of caution by getting a qualified safety professional to provide guidance on each specific case.
2) Permit-Required. Tank cars, trucks, and trailers, dry bulk tanks and trailers, railroad tank cars, and similar portable tanks when fabricated, repaired or serviced are considered permit required confined spaces. Fumes from welding equipment or devices such as generators, etc. may compromise air quality.
3) Typically Not Permit-Required. For most residential construction sites, typical confined spaces, such as attics, basements and crawl spaces, would not contain the hazards covered by permit-required entry. *
4) Permit-Required. Don't say "Eww" - Hazardous gases are serious business.
*As always, employers must have a competent person to evaluate if a permit is required.