OSHA standards for confined space entry work vary, depending on what type of work you are performing.
The 1910 general industry standards apply to work conducted in most manufacturing environments, service industries, and medical and dental fields. The OSHA general industry standards have very explicit requirements for confined space entry work listed in their 1910.146 permit-required confined space entry standards.
OSHA 1926 construction standards cover work performed during new construction, demolition operations, and major renovation jobs. The OSHA construction standards currently have a rather vague requirements regulating confined space work in Subpart C, paragraphs 1926.21(b)(6)(i) and (ii). OSHA does have a draft standard for confined space entry work in the construction industry in the final stages of development, and it is very similar to the requirements in the 1910 general industry confined space standard. Therefore, many employers in the construction industry implement the requirements of the 1910 standards to protect their employees during the interim.