Why are there six date columns instead of four?

As explained in the Applicability section of the eTool, Subpart S contains installation requirements that apply based on the time period in which an installation was built or last modified. Nuances in the regulatory text result in unique sets of requirements applying to installations built or last modified on April 16, 1981, and August 13, 2007. The April 16, 1981, and August 13, 2007, columns are included in the eTool to provide a complete and accurate display of OSHA requirements. As a practical matter, however, very few employers, if any, will need to concern themselves with the two date-specific columns.

Paragraph (b) of § 1910.302 generally addresses the application of Subpart S installation requirements in §§ 1910.303 through 1910.308. Paragraph (b)(1) of § 1910.302 lists requirements that apply regardless of the date of installation. Paragraph (b)(2) of that section states that every electrical installation and all utilization equipment installed or overhauled after March 15, 1972, must comply with §§ 1910.302 through 1910.308, except as noted in paragraphs (b)(3) and (b)(4). Paragraph (b)(3) lists requirements that apply only to electrical installations and utilization equipment installed after April 16, 1981. Paragraph (b)(4) lists requirements that apply only to electrical installations and utilization equipment installed after August 13, 2007. In addition, however, several provisions in §§ 1910.303 through 1910.308 set applicability dates of their own. The following table lists Subpart S provisions that contain separate applicability dates:

Explanations of Subpart S provisions
Subpart S Provisions Explanation
§ 1910.303(g)(1)(i)(A)
§ 1910.303(g)(1)(iv)(B)
Table S-1
Notes to Table S-1		 A note to Table S-1, which is referenced in paragraphs (g)(1)(i)(A) and (g)(1)(iv)(B) of § 1910.303, provides alternative clear working space distances for installations built before April 16, 1981.
§ 1910.303(g)(1)(vi)(A)
§ 1910.303(g)(1)(vi)(B)		 Paragraphs (g)(1)(vi)(A) and (g)(1)(vi)(B) of § 1910.303 apply different minimum headroom requirements depending on whether the installation was built before August 13, 2007, or on or after August 13, 2007.
§ 1910.303(h)(4)(i)(B)
§ 1910.303(h)(5)(i)
Table S-2
Notes to Table S-2		 A note to Table S-2, which is referenced in paragraphs (h)(4)(i)(B) and (h)(5)(i) of § 1910.303, provides alternative minimum clear working space distances for installations built before April 16, 1981.
§ 1910.303(h)(5)(v)
Table S-3
Note to Table S-3		 A note to Table S-3, which is referenced in paragraph (h)(5)(v) of § 1910.303, provides alternative minimum elevation distances for installations built before August 13, 2007, and for installations built before April 16, 1981.
§ 1910.304(c)(2)
Table S-6		 Table S-6, which is referenced in paragraph (c)(2) of § 1910.304, applies different clearances from ground depending on whether the installation was built before August 13, 2007, or on or after August 13, 2007.
§ 1910.304(g)(4)(iii) Paragraph (g)(4)(iii) of § 1910.304 provides an alternative grounding method for grounding-type receptacles on extensions of existing branch circuits that do not have an equipment grounding conductor and were installed before August 13, 2007.
§ 1910.304(g)(8)(iii) Paragraph (g)(8)(iii) of § 1910.304 provides an alternative grounding method for fixed electric equipment installed before April 16, 1981.
§ 1910.306(j)(1)(ii) Paragraph (j)(1)(ii) of § 1910.306 requires that receptacles located within 15 feet of the inside walls of a pool be protected by ground-fault circuit interrupters and applies only to installations built after August 13, 2007.
§ 1910.306(j)(2)(i) Paragraph (j)(2)(i) of § 1910.306 applies to outdoor pool areas and provides an alternative compliance option for lighting fixtures and lighting outlets installed before April 16, 1981
§ 1910.307(b) Paragraph (b) of § 1910.307 applies documentation requirements to areas designated as hazardous (classified) locations under the Class and Division system established after August 13, 2007.