INTRODUCTION

The primary objective for a water treatment plant electrical system is safety and reliability. Cost-effectiveness is important when safety and reliability have been established. The electrical system in a typical water treatment plant comprises approximately 5% to 10% of the construction cost. A robust design of the electrical system with spare conduit where needed is desirable. Water treatment plants are usually permanent facilities. Many have been in place more than 100 years. For that reason, high-quality wiring and equipment are cost-effective in most cases. Electrical system design is an iterative process that involves the overall water system, treatment considerations, architecture, structures, security, and HVAC.

The design, installation, testing, and specifications for electrical equipment are thoroughly covered by codes and standards. These codes and standards are no substitute for professional judgment. Electrical engineers use many of these standards in specifying myriad items of conduit, wiring, and equipment.

Electrical engineers are responsible for detailed design of the system. Nonelectrical engineers and managers can aid the design process by being familiar with the NEMA handbook and other standards. Civil and environmental engineers usually specify and select treatment and pumping equipment, most of which operates with electric motors and controllers. The design process involves input from all professionals and managers involved with the project.

CODES AND STANDARDS

The National Fire Protection Association (NFPA) has published and updated the National Electrical Code (NEC) since 1911. The NEC 2002 handbook is the 9th edition. The code...