Design criteria and analysis of rigid bus structures for outdoor and indoor, air insulated, alternating current substations for determination of ampacity, radio influence, vibration, forces due to gravity and wind and short circuit current, thermal expansion, and the effects of same. Expand and improve on the guidance given in the withdrawn standard. Revision Standard - Superseded. Rigid-bus structures for outdoor and indoor, air insulated, and alternating current substations are covered. Portions of this guide are also applicable to strain bus structures or direct current substations, or both. Ampacity, radio influence, vibration, and forces due to gravity, wind, fault cur-rent, and thermal expansion are considered. Design criteria for conductor and insulator strength calculations are included.