| Ω | Ohm |
| Φ | Phase |
| A | Amperes |
| AC | Alternating Current |
| A/C | Air Conditioning |
| AFCI | Arc Fault Circuit Interrupter |
| AHU | Air Handling Unit |
| AIC | Ampere Interrupting Capacity |
| AL | Aluminum |
| ATS | Automatic Transfer Switch |
| ATC | Automatic Temperature Control |
| AWG | American Wire Gauge |
| BTU | British Thermal Units |
| C | Conduit |
| CATV | Cable Television or Community Antennae Television |
| CB | Critical Branch |
| C/B | Circuit Breaker |
| CBM | Certified Ballast Manufacturer |
| CCT | Circuit (also: CIR, CKT) |
| CCTV | Closed Circuit Television |
| CD | Candela |
| CIR | Circuit (also: CCT, CKT) |
| CKT | Circuit (also: CCT, CIR) |
| CLF | Current Limiting Fuse |
| CPT | Control Power Transformer |
| CT | Current Transformer |
| CU | Copper |
| dB | Decibel |
| DC | Direct Current |
| DIA | Diameter |
| EB | Equipment Branch |
| EC | Electrical Code or Electrical Contractor |
| EF | Exhaust Fan |
| ELEV | Elevator |
| EM | Emergency |
| EMT | Electrical Metallic Tubing |
| EP | Emergency Power |
| EPO | Emergency Power Off (Button or Switch) |
| EWC | Electric Water Cooler |
| F | Fuse |
| FA | Fire Alarm |
| FAA | Fire Alarm Annunciator |
| FLA | Full Load Amperes |
| FMC | Flexible Metal Conduit |
| G | Ground |
| GFCI, GFI | Ground Fault Circuit Interrupter |
| GND | Ground |
| GRMC | Galvanized Rigid Metal Conduit |
| HOA | Hand-Off-Automatic Switch |
| HVAC | Heating, Ventilation, Air Conditioning |
| HZ | Hertz |
| IEEE | Institute of Electrical and Electronic Engineers |
| IG | Isolated Ground |
| IMC | Intermediate Metal Conduit |
| INT | Interlock |
| KCMIL | Thousand Circular Mils |
| KVA | Kilovolt-Amperes |
| KVAR | Kilovolt-Amperes Reactive |
| LFMC | Liquid Tight Flexible Metal Conduit |
| LTG | Lighting |
| LRA | Lock Rotor Amps |
| MC | Metal Clad Cable |
| MCB | Main Circuit Breaker |
| MCC | Motor Control Center |
| MCP | Motor Circuit Protection |
| MI | Mineral Insulated |
| MLO | Main Lugs Only |
| MW | Megawatt |
| NC | Normally Closed |
| NEC | National Electrical Code |
| NEMA | National Electrical Manufacturers Association |
| NFPA | National Fire Protection Association |
| NL | Night Light |
| NO | Normally Open or Number |
| P | Pole |
| PB | Push Button or Panic Button or Pull Box |
| PNL | Panel |
| PWR | Power |
| PT | Potential Transformer |
| QTY | Quantity |
| REQ | Required |
| RCCB, RCB | Residual-Current Circuit Breaker |
| RCD | Residual-Current Device |
| RMC | Rigid Metal Conduit |
| RMS | Root Mean Squared |
| RNC | Rigid Non-Metallic Conduit |
| RTS | Remote Test Station |
| RTU | Roof Top Unit |
| SE | Service Entrance |
| SEB | Service End Line Box or Service Electrical Box |
| SP | Spare |
| ST | Shunt Trip |
| SW | Switch |
| SYM | Symmetrical |
| TEL | Telephone |
| TGB | Telecommunications Grounding Busbar |
| TMCB | Thermal Magnetic Circuit Breaker |
| UG | Under Ground |
| UL | Underwriters Laboratory |
| V | Volt |
| VA | Volt-Ampere |
| VFD | Variable Frequency Drive |
| VT | Voltage Transformer |
| W | Watt or Wire |
| WH | Water Heater |
| WP | Weatherproof or Waterproof |
| XFMR | Transformer |
