Electrical System

Every building electrical system, from a house to a hospital, is built from the same basic parts:

• Utility service and meter: the point where the utility's power enters the building
• Service entrance equipment: the main switchboard or switchgear with the main disconnect
• Transformers: step the voltage down, for example from 480V to 208/120V
• Panelboards: divide power into branch circuits for each floor or area
• Branch circuits: the wiring that feeds lighting, receptacles and equipment
• Overcurrent protection: circuit breakers and fuses that open when current is too high
• Grounding and bonding: conductors that keep exposed metal at a safe voltage and give fault current a path so breakers trip
• Emergency and standby power: generators, transfer switches and UPS systems
• Motor control centers and VFDs that run HVAC and plumbing motors

Power arrives from the utility either at low voltage from a utility transformer, or at medium voltage for large buildings and campuses that own their own transformers. It passes through the main service equipment, then through feeders to distribution panels and transformers, and finally through branch circuits to the loads. Protective devices at each level are sized so that a fault trips the nearest breaker instead of shutting down the whole building, which is called selective coordination.

In US commercial buildings, a common arrangement is 277/480V three-phase for large motors and lighting, and 120/208V three-phase for receptacles and small equipment. Houses typically get 120/240V single-phase service.

Electrical systems are usually grouped by purpose. The NEC treats backup power separately in Article 700 (emergency systems), Article 701 (legally required standby systems) and Article 702 (optional standby systems). The main groups are:

• Normal power: everyday distribution for lighting, receptacles and equipment
• Emergency power: backup for life safety loads such as egress lighting and fire alarm systems, which must transfer within seconds of a power loss
• Standby power: legally required standby (NEC Article 701), such as smoke control and sewage pumps, and optional standby (NEC Article 702) for loads such as HVAC, refrigeration or IT
• Low-voltage systems: fire alarm, data, security, audiovisual and controls wiring
• Lighting and lighting controls
• Single-phase and three-phase: single-phase is common in homes and small buildings, three-phase in commercial buildings and for large motors

In the US, electrical installations follow NFPA 70, the National Electrical Code (NEC), as adopted by each state or city. Work on or near energized equipment is covered by NFPA 70E, which drives arc flash studies, equipment labels and protective equipment. NFPA 70B covers maintenance of electrical equipment, and NFPA 110 covers emergency and standby generator systems, including their testing.

Typical maintenance includes infrared scans to find hot connections, torque checks during planned shutdowns, cleaning and inspecting switchgear, exercising and testing breakers, testing transfer switches, and running generators under load. Loose connections, overloaded circuits and aging breakers that fail to trip are common causes of outages and electrical fires.

The core documents are the one-line diagram, panel schedules showing what each circuit feeds, the arc flash study and labels, generator and transfer switch test logs, and infrared scan reports. Teams also track equipment age, spare capacity on each panel, and which critical loads are on emergency or standby power.

In a digital twin such as Syyclops, transformers, switchboards, panelboards and generators can be tracked as assets in the same model as the rest of the building, located on their floors and in their rooms, with work orders and documents attached.