Tracked Changes. High-Voltage Switchgear and Controlgear. Gas-filled wrought steel enclosures|Type p protected electrical equipment, Welding, Enclosures, High-voltage equipment, Pressure regulators, Electric enclosures, Design, Approval testing, Fusion welding, Marking, Certification (approval), Inspection, Wrought alloys, Dimensional tolerances, Performance testing, Switchgear, Protected electrical equipment, Defects, Designations, Test specimens, Acceptance (approval), Form tolerances, Non-destructive testing, Steels, Welded joints, Documents, Electrical insulation devices, Electric control equipment