Electrical Engineering Design Services: What’s Included in a Full CD Package

When an architect delivers a building’s design drawings to the contractor, those drawings define what the building looks like. When an electrical engineer delivers a full construction document package, those documents define how the building’s electrical systems will be built — every circuit, every panel, every conduit run, every lighting fixture, every fire alarm device, and every control sequence. The quality and completeness of that electrical CD package directly determines how accurately the contractor can price the work, how efficiently installation proceeds, and how reliably the building performs after occupancy.

At Budlong, our electrical engineering design services team delivers complete CD packages for commercial, healthcare, educational, and institutional projects throughout California. This guide describes every component of a full electrical engineering construction document package — what each document is, why it is required, and how it is used through design, permitting, construction, and operations.

1. What Is a Full Electrical CD Package?

A full electrical engineering construction document (CD) package is the complete set of documents that define the electrical systems of a building with sufficient precision and completeness for contractors to bid, procure equipment for, install, and test those systems without requiring engineering decisions or clarifications beyond the scope of normal submittal review. It is distinct from schematic design drawings (which show system concepts) and design development drawings (which show coordinated layouts) in that CDs are permit-ready, construction-ready documents.

A full electrical CD package is also the primary tool for contractor bidding. Contractors use the drawings and specifications to quantify materials, estimate labor hours, price equipment, and identify scope boundaries. Incomplete or ambiguous CDs produce inaccurate bids, excessive RFIs during construction, and change orders that cost the owner far more than the cost of more thorough upfront engineering. Budlong’s electrical engineering approach treats CD completeness as a direct service to the owner’s budget management.

2. The Electrical Drawing Set

The electrical drawing set is the graphical component of the CD package. It communicates equipment locations, routing, dimensions, connections, and system configurations through a defined set of drawing types organized by sheet number and discipline prefix.

Electrical Site Plan

The electrical site plan shows the building’s electrical infrastructure at site scale — utility service entrance location, underground conduit routing from the utility transformer to the service entrance, exterior lighting fixtures and circuit routing, parking area lighting, site signage power, and EV charging station locations. For multi-building campuses, the site plan also shows the primary electrical distribution between buildings. The site plan coordinates with the civil, landscape, and architectural site plans to confirm that underground electrical routing avoids conflicts with other site utilities and structures.

Electrical Floor Plans

Electrical floor plans are the primary coordination drawings for electrical installation. They show, on each floor of the building: power receptacle and equipment outlet locations with circuit designations, lighting fixture locations and circuit designations, electrical device locations (switches, occupancy sensors, photosensors, panels), conduit routing for major feeders, electrical room layouts, and equipment clearance zones. Floor plans are produced at the same scale as the architectural floor plans to enable direct overlay comparison and coordination with structural and MEP drawings. MEP drafting services at Budlong produce electrical floor plans in Revit or AutoCAD coordinated with the mechanical and plumbing disciplines.

Electrical Reflected Ceiling Plan

The electrical reflected ceiling plan (RCP) shows lighting fixture locations, emergency lighting and exit sign locations, speakers, projectors, and other ceiling-mounted devices within the context of the architectural ceiling grid. The electrical RCP is produced in coordination with the architectural RCP to confirm that lighting fixtures are located within ceiling modules and that fixture types are compatible with the ceiling system. Lighting circuit assignments shown on the RCP connect to the panelboard schedules for circuit sizing verification.

3. Single-Line Diagram

The single-line diagram (also called the one-line diagram) is the most important drawing in the electrical CD package. It is a schematic representation of the complete electrical distribution system — from the utility service entrance through all switchgear, transformers, panelboards, motor control centers, and major equipment — using a single line to represent three-phase conductors and standardized symbols for each component.

What the Single-Line Diagram Shows

A complete single-line diagram annotates the following information for every component in the distribution system: utility service voltage and available fault current, main switchboard or service entrance equipment rating (ampacity, voltage, AIC rating), transformer ratings (kVA, primary voltage, secondary voltage, impedance), feeder conductor sizes and conduit types, panelboard designations and ampacity ratings, main breaker or fused switch ratings with interrupting capacity, and connections to major equipment loads (mechanical equipment, elevators, emergency systems). The hierarchy from utility service through all downstream distribution is shown in a logical top-to-bottom or left-to-right flow that allows the plan reviewer and the contractor to trace any circuit from source to load.

NEC Requirements for Single-Line Diagrams

While the NEC does not mandate a specific single-line diagram format, California plan check authorities require a single-line diagram as part of the electrical permit submission to demonstrate that the distribution system is correctly engineered. The single-line must be consistent with the load calculations — equipment ratings on the single-line must match or exceed the calculated demand loads — and with the panelboard schedules. Inconsistencies between the single-line, load calculations, and panel schedules are common plan check comment items that delay permit issuance. What sets top electrical engineering firms apart is in part the internal quality control process that catches these inconsistencies before permit submittal.

4. Panelboard Schedules and Equipment Schedules

Panelboard schedules and equipment schedules are tabular drawing documents that provide detailed information about electrical distribution equipment that cannot be efficiently shown graphically on floor plans or single-line diagrams.

Panelboard Schedules

As described in the load calculation guide, panelboard schedules list every circuit in each panelboard with circuit number, description, poles, breaker ampacity, connected load, and phase. They verify that each panel is phase-balanced and that the feeder ampacity is adequate for the panel’s total load. For large commercial projects with dozens of panelboards, the panel schedule set can be a substantial document — but every circuit in every panel must be accounted for to produce a complete and permit-compliant CD package.

Equipment Schedules

Equipment schedules tabulate the specifications for major electrical equipment: main switchboards, distribution switchboards, panelboards, transformers, motor control centers, automatic transfer switches, and generators. Each schedule entry shows the equipment designation, voltage, ampacity, fault current rating (AIC or kAIC), number of poles or positions, bus material, mounting type, and applicable standards. Equipment schedules are used by the contractor to procure equipment that meets the engineer’s specifications and by the owner’s facility manager to maintain an accurate record of installed equipment.

5. Lighting Design Deliverables

Lighting design is a significant component of the electrical CD package for commercial buildings, encompassing both functional and aesthetic objectives. At Budlong, architectural lighting design services are an integrated part of the electrical engineering scope on commercial projects.

Fixture Schedule

The fixture schedule lists every luminaire type used in the project with its type designation (used to identify fixtures on the floor plans), manufacturer and model number, lamp type, wattage, efficacy, color temperature, CRI, mounting type, and California Title 24 listing status. The fixture schedule is the primary procurement document for lighting materials — it must be complete and accurate for the contractor to order the correct fixtures in the correct quantities.

Photometric Analysis

For projects where specific illuminance targets are required — office workplane illuminance, retail merchandise lighting, hospital patient room lighting levels — the electrical engineer produces photometric analysis using software such as AGi32 or DIALux to verify that the proposed fixture layout achieves the design illuminance targets. Healthcare facilities, schools, and court facilities have mandatory minimum illuminance requirements per IESNA Lighting Handbook; these must be documented in the photometric analysis included in the CD package.

Lighting Controls Design

California Title 24 requires sophisticated lighting controls in most commercial space types — occupancy sensors, daylighting controls, manual dimming, and demand response capability. The lighting controls drawings show the location and type of every control device, the zones they control, and the wiring connections from sensors and switches to the lighting control panels or relay panels. Controls sequences of operation are documented in the specifications to define how the system is programmed and commissioned. Sustainable lighting design integrates controls as a fundamental efficiency measure rather than an afterthought.

6. Special Systems Design

Special systems — also called low-voltage systems or building technology systems — are a growing component of electrical engineering scope in modern commercial buildings. The extent of special systems in the CD package depends on the building type, owner requirements, and the agreed engineering scope.

Fire Alarm Systems

Fire alarm system design is one of the most code-sensitive components of the electrical CD package. California Fire Code and NFPA 72 define the detection, notification, and monitoring requirements for different occupancy types. The fire alarm drawings show device locations (smoke detectors, heat detectors, pull stations, notification appliances, and sprinkler flow switches), wiring pathways, and fire alarm control panel locations. For complex projects, the fire alarm design may be performed by the electrical engineer of record or delegated to the fire alarm specialty contractor — but the electrical CD package must define the system basis of design and performance requirements regardless of who prepares the final shop drawings. Fire safety engineering in MEP at Budlong encompasses both fire alarm design and integration with the broader MEP systems.

Telecommunications and Data Infrastructure

The telecommunications and data infrastructure drawings show conduit pathways for data and voice cabling, telecommunications room locations, equipment rack layouts, and pathway requirements to workstations and access points. In many commercial buildings, the structured cabling system is installed by a low-voltage specialty contractor using drawings from a technology consultant, but the electrical engineer must coordinate the conduit and pathway infrastructure and the power requirements for active network equipment and wireless access points. Technology systems services from Budlong address telecommunications infrastructure as part of the integrated MEP scope.

Security and Access Control

Security system drawings define the locations of cameras, card readers, intrusion detection devices, and security panels, as well as the power requirements for each device. Access control systems require 24V DC power supplies, and door hardware (electric locks, magnetic locks, and electric strikes) requires power and control wiring coordinated with both the security system and the door hardware schedule. The intersection of security and audio-visual integration is increasingly an integrated engineering challenge addressed within the special systems scope.

7. Electrical Specifications

Electrical specifications are the text component of the CD package that defines quality, performance, and installation requirements for all electrical systems and materials — information that drawings alone cannot convey. Specifications are organized by CSI MasterFormat division number and are typically included in the project’s Project Manual.

Division 26 — Electrical

Division 26 specifications cover all power distribution and lighting systems: wiring methods and materials (conduit types, wire types, and installation requirements), raceways and boxes, wiring devices, switchgear and panelboards, transformers, motors and motor controls, lighting equipment, and testing and commissioning requirements. Division 26 is the most extensive electrical specification division for most commercial projects, and its quality directly determines the quality of electrical installation.

Division 27 — Communications

Division 27 specifications cover telecommunications infrastructure including structured cabling systems, telecommunications rooms, and audiovisual systems. These specifications define cabling standards (typically TIA-568 for horizontal cabling), termination requirements, testing requirements, and system performance benchmarks.

Division 28 — Electronic Safety and Security

Division 28 covers fire alarm systems, access control, video surveillance, and intrusion detection systems. Fire alarm specifications are particularly detailed, defining NFPA 72 compliance requirements, device types and spacing, monitoring interface requirements, and acceptance testing procedures.

8. Supporting Calculations and Studies

Beyond the drawings and specifications, a complete electrical CD package includes supporting engineering calculations and studies that document the basis for sizing decisions and verify code compliance.

Load Calculations

As detailed in the load calculation guide, NEC Article 220 calculations documenting the basis for service entrance size, feeder sizes, and panelboard ratings are required components of the permit submittal. These calculations are typically presented as a structured calculation report organized by load category and system level.

Short-Circuit Analysis

Short-circuit analysis documents the maximum available fault current at each level of the electrical distribution system and verifies that all equipment has adequate AIC (ampere interrupting capacity) ratings. This analysis is typically required for permit submittal and is also used for arc flash analysis, which is increasingly required or expected for healthcare and industrial facilities.

Arc Flash Analysis

Arc flash analysis per NFPA 70E and IEEE 1584 calculates the arc flash incident energy at each piece of switchgear and panelboard to determine the required PPE (personal protective equipment) for electrical workers performing energized work. Arc flash analysis is not universally required for building permit submittal, but NFPA 70E requires that employers provide arc flash hazard analysis for electrical equipment in workplaces. For healthcare, industrial, and mission-critical facilities, arc flash analysis is a standard deliverable. Fire life safety essentials for workplace electrical safety depend on arc flash analysis as a foundational assessment.

9. California Title 24 Compliance Documentation

California Title 24 Part 6 electrical compliance documentation is a mandatory component of the electrical CD package for all California commercial building permit applications. It is separate from and in addition to the NEC-required engineering documents.

LTG-1 Certificate of Compliance

LTG-1 is the primary lighting compliance form that documents that the installed lighting system meets Title 24 mandatory lighting power density limits for all space types in the building. The electrical engineer completes LTG-1 based on the fixture schedule and floor plan areas, calculating the installed lighting power density (W/SF) for each space type and comparing it to the applicable Title 24 allowance. LTG-1 must be signed by the engineer of record, included in the permit submittal, and posted at the jobsite during electrical inspection.

LTG-2 Lighting Controls Credit Worksheet

LTG-2 documents the lighting controls installed in each space and the compliance credit claimed for those controls. Title 24 mandatory controls requirements — occupancy sensors in specific space types, automatic shutoff, daylighting controls in daylit zones — are verified on LTG-2. The form also calculates the additional power density allowance earned through certain advanced controls installations.

ELC Electrical Power Distribution Form

The ELC form documents compliance with Title 24 efficiency requirements for electrical power distribution systems above defined size thresholds — including transformer efficiency requirements and wire sizing requirements for oversized neutrals in three-phase systems with significant nonlinear loads.

10. Who Uses Full Electrical CD Services?

11. Related Reading

For technical reference, consult the NFPA 70 National Electrical Code, the California Energy Commission Title 24 compliance documentation resources, Consulting-Specifying Engineer electrical design resources, the Illuminating Engineering Society of North America Lighting Handbook, and BICSI telecommunications infrastructure standards.

12. Frequently Asked Questions