Chapter 7: Electrical Systems

Anchor: #i1005840

Section 1: Overview

Anchor: #i1005846

Introduction

Electrical system design involves many considerations. This chapter covers the areas of special concern to roadway illumination.

Anchor: #i1005857

National Electrical Code

The National Electrical Code (NEC) contains nationally recognized rules and regulations for the installation and use of electrical power. The NEC is written by the National Fire Protection Association (NFPA) (see References, in Chapter 1, Section 1, for information on obtaining the publication). Each section is written by committees of experts. The NEC is considered the minimum acceptable standard for a safe installation.

Most local authorities adopt the NEC into law. Although the NEC is not law on state property, it should be complied with to ensure safe installation of electrical systems. Allow exceptions only in special cases where the intent of the NEC is satisfied.

The following articles of the 2002 NEC Handbook are of particular relevance to roadway lighting, sign lighting, and traffic signals:

NEC Handbook Articles Relevant to Roadway Lighting

Number & Title

Number & Title

100

Definitions

342

Intermediate Metal Conduit: Type IMC

110

Requirements for Electrical Installations

344

Rigid Metal Conduit: Type RMC

200

Use and Identification of Grounded Conductors

348

Flexible Metal Conduit: Type FMC

210

Branch Circuits

350

Liquid-tight Flexible Metal Conduit: Type LFMC

215

Feeders

352

Rigid Nonmetal Conduit: Type RMC

220

Branch-Circuit, Feeder, and Service Calculations (Parts I & II)

356

Liquid-tight Flexible Nonmetallic Conduit: Type LFNC

225

Outside Branch Circuits and Feeders

358

Electrical Metallic Tubing: Type EMT

230

Services

362

Electrical Nonmetallic Tubing: Type ENT

240

Overcurrent Protection

396

Messenger Supported Wiring

250

Grounding

404

Switches

280

Surge Arresters

408

Switchboards and Panelboards

300

Wiring Methods

410

Luminaires (Lighting Fixtures), Lampholders, and Lamps

310

Conductors for General Wiring

450

Transformers and Transformer Vaults (Including Secondary Ties)

314

Outlet, Device, Pull and Junction Boxes; Conduit Bodies; Fittings; and Manholes

600

Electric Signs and Outline Lighting



Anchor: #i1005885

Electrical Details

Current TxDOT electrical specifications are contained in the Electrical Details (ED) Standard Sheets of TxDOT’s Traffic Operations Standard Plans (see References in Chapter 1, Section 1, for information on obtaining the publication).

Previous page  Next page   Title page