- 13400 - Measurement and Control Instrumentation
- 15510 - Heating Boilers and Accessories
- 16200 - Electrical Power
- 16210 - Electrical Utility Services
- 16260 - Static Power Converters
- 16300 - Transmission and Distribution
- 16320 - High-voltage Switching And Protection
- 16340 - Medium-Voltage Switching and Protection As
- 16360 - Unit Substations
- 16430 - Low-Voltage Switchgear
- 16440 - Switchboards, Panelboards, and Control Cen
- 16450 - Enclosed Bus Assemblies
- 16460 - Low-Voltage Transformers
- 23 52 00 - Heating Boilers
- 23 52 16 - Condensing Boilers
- 23 52 19 - Pulse Combustion Boilers
- 23 52 23 - Cast-Iron Boilers
- 23 52 33 - Water-Tube Boilers
- 23 52 39 - Fire-Tube Boilers
- 26 10 00 - MEDIUM-VOLTAGE ELECTRICAL DISTRIBUTION
- 26 11 00 - Substations
- 26 13 00 - Medium-Voltage Switchgear
- 26 13 13 - Medium-Voltage Circuit Breaker Switchgear
- 26 13 16 - Medium-Voltage Fusible Interrupter Switchgear
- 26 13 19 - Medium-Voltage Vacuum Interrupter Switchgear
- 26 18 00 - Medium-Voltage Circuit Protection Devices
- 26 18 29 - Medium-Voltage Enclosed Bus
- 26 18 33 - Medium-Voltage Enclosed Fuse Cutouts
- 26 18 36 - Medium-Voltage Enclosed Fuses
- 26 18 39 - Medium-Voltage Motor Controllers
- 26 20 00 - LOW-VOLTAGE ELECTRICAL TRANSMISSION
- 26 22 00 - Low-Voltage Transformers
- 26 23 00 - Low-Voltage Switchgear
- 26 24 00 - Switchboards and Panelboards
- 26 25 00 - Enclosed Bus Assemblies
- 26 29 23 - Variable-Frequency Motor Controllers
- 26 30 00 - FACILITY ELECTRICAL POWER GENERATING AND STORING EQUIPMENT
- 26 33 00 - Battery Equipment
- 26 33 33 - Static Power Converters
- 26 33 43 - Battery Chargers
- 26 33 53 - Static Uninterruptible Power Supply
- 26 35 36 - Slip Controllers
- 26 35 43 - Static-Frequency Converters
- 33 71 00 - Electrical Utility Transmission and Distribution
- 33 71 73 - Electrical Utility Services
- 33 72 00 - Utility Substations
- 33 75 00 - High-Voltage Switchgear and Protection Devices
- 33 75 36 - High-Voltage Utility Fuses
- 33 75 39 - High-Voltage Surge Arresters
- 33 77 26 - Medium-Voltage Utility Fusible Interrupter Switchgear
- 40 90 00 - INSTRUMENTATION AND CONTROL FOR PROCESS SYSTEMS
- 48 00 00 - ELECTRICAL POWER GENERATION