What is a permit-required confined space?

According to OSHA, a permit-required confined space is a confined space that meets any of the following criteria:

  1. Contains, or has the potential to contain, a hazardous atmosphere,
  2. Contains a material the has the potential for engulfing an entrant,
  3. Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section, or
  4. Other recognized health or safety hazards.