scope:

This recommended practice is for the seismic design of substations, excluding Class 1E equipment for nuclear power generation stations. Seismic qualification of electrical equipment and their supports is emphasized.

The most important goal of this recommended practice is to provide a single standard set of design recommendations for seismic qualification of each equipment type. Design recommendations consist of seismic criteria, qualification methods and levels, structural capacities, performance requirements for equipment operation, installation methods, and documentation. This will reduce costs, because the manufacturers can qualify their equipment once for each qualification level and eliminate specialized testing.

Three qualification levels are recommended. They are low, moderate, and high. The user should determine the desired qualification level when purchasing the equipment.

This recommended practice is divided into nine clauses (1 through 9) and 20 annexes (A through T). Clauses contain general seismic design requirements. Annexes contain equipment-specific seismic design requirements and are located after the clauses. If the type of equipment to be qualified is not specifically addressed in Annexes C through O, the seismic design requirements of Annex B may be used, if applicable.

Annexes are titled normative or informative. Normative annexes are official parts of this recommended practice. Informative annexes are for information only and are not an official part of this recommended practice.

The following references are recommended for seismic design of substation structures, foundations, and anchorage:¹

- Buildings: Uniform Building CodeTM (UBC), Southern Building Code, Mexican Code (MDOC/CFE), National Building Code (BOCA), or National Building Code of Canada (NBCC).

- Anchorage design: American Society of Civil Engineers (ASCE) Substation Structure Design Guide (draft).

NOTE - Anchorage design requirements are found in the ASCE Substation Structure Design Guide (draft). Anchorage requirements for equipment qualification are provided in this recommended ractice.

- Foundation design: UBC MDOC/CFE, Southern Building Code, American Concrete Institute (ACI), ASCE Substation Structure Design Guide (draft), or NBCC.

- Structures: Strain bus structures, A-Frames, racks, box structures, rigid bus supports, and all other such substation structures. ASCE Substation Structure Design Guide (draft).

- Rigid bus: ASCE Substation Structure Design Guide (draft).

The ASCE "Guide for Improved Earthquake Performance of Power Systems," (draft) is in preparation. It will illustrate many methods of installing substation equipment and discuss their advantages. It will also provide useful information for evaluating existing installation details for good earthquake performance.

¹Information on these and additional references can be found in Clause 2..