Electrical Engineering Standards

Review Design Standards General Statements before utilizing this web page.

On this page:
Building Codes & Industry Standards
Denver Service Center (DSC) Requirements
National Park Service (NPS) Requirements

Building Codes & Industry Standards

  • ASHRAE 90.1 2016 (American Society of Heating, Refrigerating and Air Conditioning Engineers)
  • EIA/TIA Standards 568 & 569 (Electronic Industries Alliance/Telecommunications Industry Association)
  • IEEE Standards
  • IES Lighting Handbook 10th Edition (Illuminating Engineering Society)
  • NESC 2017 (National Electrical Safety Code)
  • NFPA (National Fire Protection Association) Codes and Standards - see Fire Protection Engineering Standards
  • NFPA 70: NEC (National Electrical Code) 2020
  • UL (Formerly Underwriters Laboratories)

Denver Service Center (DSC) Requirements


  • See Reference Manual (RM) 53B: Rights-of-Way (ROW). (Also reference on Civil (Site) & Enivironmental Engineering Standards.)
  • Initiate planning activities with utility companies as early as possible.
    • Architect/Engineer (A/E) may be required to design upgrades/changes to NPS-owned utilities.
    • Provide utility coordination services including investigations, coordinations, notifications, and meetings with utility providers along the project corridor.
      • Initiate contact, communication, and coordination services at Predesign (PD) and Schematic Design (SD) phases.
      • Document interactions with emails, meeting notes, etc.
      • Continue activities and documentation through Design Development (DD) and Construction Documents (CD) phases. Use information obtained to fully develop and communicate options, ideas, and issues throughout design process.
      • Consider how design changes affect all utilities and continually communicate with utility companies.
      • Prepare and send written project notifications to utility owners including copies of construction documents.
      • Organize and conduct meetings with all utility owners including preparation of exhibits and meeting minutes.
      • Using information gathered during sub-surface utility investigations, identify utility conflicts and confirm with utility owners.
      • Evaluate relocation alternatives with utility owners and project team.
      • Prepare Technical Letters for Cost Proposals; both requests and final responses.
  • Utilize underground distribution as much as possible.
  • NPS prefers not to own and operate utilities.
  • TVSS (Transient Voltage Surge Supressor) Protection on service entrances.
  • Owner demand metering complying with EPACT 2005 (Energy Policy Act) for Federal buildings in addition to utility company metering.


  • Site specific. In general, Schedule 40 PVC (polyvinyl chloride) for underground.
  • PVC coated rigid metal elbows for risers to grade.
  • Minimum branch circuit conduit size: 3/4 inch.
  • Provide conduit for wiring (minimum size 3/4 inch).
  • Non-metallic conduit or tubing is not allowed in interior dry locations unless required by code.
  • Route a separate equipment grounding conductor, sized per NEC requirements, in conduits.
  • Heavy duty disconnect switches.

Equipment and Materials

  • Listed and labeled as defined in NEC Article 100 for application.

Load Requirements

  • NEC 2017
  • 25% minimum spare capacity typical for future expansion.

Overcurrent Protection

  • Fully rated - Series rated is not desired.
  • Breakers preferred for reset capability (sizes 15 amperes or greater).
  • Fuse selection shall comply with NEC requirements and equipment manufacturers recommendations.

Power Wiring

  • THWN/THHN (Thermoplastic Heat and Water Resistant Nylon Coated/Thermoplastic High Heat Resistant Nylon Coated)
  • Underground - THWN/XHHW (Cross-Linked High Heat Water-resistant Insulated Wire)
  • No MC or AC (Metal Clad or Armor Clad) type cabling in walls in new construction.
  • No surface mounted MC or AC type cabling where rigid raceway can be used.
  • Copper conductors
  • Copper Buswork


  • EIA/TIA Standards, see above.
  • Category 6 Cabling - (2) per 3/4 inch conduit; (1) Data, (1) Voice per each voice/data outlet (typical). Terminate conductors.
  • Telephone Service Entrance (Demarcation Point) - Meet local phone company requirements.
  • Architect-Engineer (AE) shall query Park for additional IT (information technology), telecom, or data system requirements.

National Park Service (NPS) Requirements

NPS Management Policies 2006 - The Guide to Managing the National Park System

  • Chapter 1 The Foundation
    • Facilities
  • Chapter 4 Natural Resource Management
    • 4.10 Lightscape Management
  • Chapter 8 Use of the Parks
    • 8.2.3 Use of Motorized Equipment
    • 8.6 Special Park Uses
    • 8.6.4 Rights-of-Way for Utilities and Roads
    • Utilities
    • Telecommunication Sites
  • Chapter 9 Park Facilities
    • 9.1 General
    • 9.1.1 Facility Planning and Design
    • Life-cycle Costs
    • Integration of Facilities into the Park Environment
    • Protection of Cultural Values
    • Adaptive Use
    • Siting Facilities to Avoid Natural Hazards
    • Sustainable Energy Design
    • 9.1.3 Construction
    • Construction Sites
    • 9.1.4 Maintenance
    • General
    • Acquisition of Environmentally Preferable and Energy-Efficient Products
    • 9.1.5 Utilities
    • Water Supply Systems
    • Wastewater Treatment Systems
    • Utility Lines
    • Historic Utilities
    • 9.1.7 Energy Management
    • 9.1.8 Structural Fire Protection and Suppression
    • 9.3 Visitor Facilities
    • 9.4 Management Facilities

Director's Orders (DOs)

Handbooks, Reference Manuals (RMs), Strategies, Plans, & other Professional Materials



Last updated: February 6, 2023

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