Architects Don't Design Electrical Systems - But They Set the Requirements That Drive Electrical Design
Electrical systems in buildings are designed by electrical engineers who are licensed to stamp and seal electrical drawings. The architect's role is to define the program requirements that drive electrical design (occupant count, equipment loads, hours of operation, lighting quality targets, backup power requirements) and to coordinate the electrical engineer's work with the architectural design (equipment room locations, conduit routing, device locations, ceiling fixture integration). The ARE PPD tests electrical system fundamentals at a level of understanding appropriate for an architect: knowing what a building's electrical service requirements are, how distribution is organized, what drives lighting design choices, and how electrical systems affect architectural planning. The specific calculations (short circuit analysis, panel sizing, load calculations) are the electrical engineer's responsibility.
Electrical Service
The electrical utility provides power to the building at a distribution voltage (typically 4,160V, 13.2kV, or 34.5kV) for large commercial buildings, or at utilization voltage (120/208V or 277/480V 3-phase) for smaller buildings. For large buildings, the utility provides medium-voltage service to a building-owned transformer that steps the voltage down to utilization voltage. The service entrance - the point where utility power enters the building - must include a main disconnect within a defined distance of the service entrance point (NEC Article 230). The main distribution switchboard or switchgear distributes power to sub-panels and feeder circuits throughout the building. Emergency power (standby or legally required) is provided by generators and/or UPS systems with automatic transfer switches.
Distribution Equipment Space
The architect must provide adequate dedicated electrical equipment space: main switchgear room or electrical room (typically 400-800 SF for a mid-size commercial building); electrical closets or panel rooms at each floor (or every other floor); transformer vaults for medium-voltage buildings (with code-required ventilation and drainage). NEC Article 110.26 requires minimum 3-foot clear working space in front of all electrical equipment (6.5 feet high and as wide as the equipment, extending 3 feet in front). This working clearance cannot be used for storage and must be maintained throughout the building's life.
Lighting Basics
Building lighting is specified in terms of: Illuminance (foot-candles, fc): Light level at the task surface; recommended by IES Lighting Handbook by task. Typical targets: office task lighting: 30-50 fc; classroom: 30-50 fc; surgical suite: 100-200 fc. Lighting Power Density (LPD, W/sq ft): ASHRAE 90.1 establishes maximum LPD by space type to limit energy consumption from lighting. Office general lighting: 0.82 W/SF maximum (ASHRAE 90.1-2019 space-by-space method). Lighting controls: ASHRAE 90.1 requires occupancy sensors and daylight dimming in spaces with sufficient daylighting; these controls can reduce lighting energy use by 30-50%.
Key Exam Points
- Electrical service: utility provides power at distribution or utilization voltage; transformer for medium voltage service to buildings.
- Main electrical equipment room: 400-800 SF typical commercial; floor-level electrical closets at each level.
- NEC 110.26: 3-foot working clearance in front of electrical equipment; cannot be used for storage.
- Illuminance: foot-candles at task surface; 30-50 fc office/classroom; higher for medical/surgical.
- LPD: ASHRAE 90.1 maximum watts/SF by space type; lighting controls reduce energy use.
AREprep's PPD building systems content covers electrical system fundamentals, service requirements, distribution layout, lighting design targets, and ASHRAE 90.1 LPD requirements - giving ARE PPD candidates the electrical systems knowledge the exam tests in building performance and system coordination questions where the architect must understand the space requirements and performance parameters of the electrical systems their consultants design.
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