Power Distribution Systems

electrical room requirements

The NEC requires that access and working space be provided and maintained around all electrical equipment to permit ready and safe access to and maintenance of the equipment. Depth of Electrical room The NEC provides minimum depths in two tables that list nominal voltages to ground. Table 10.26(A)(1) includes depths for voltages to ground up …

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fault current

Ordinary current ratings of equipment are most commonly in the range of tens or hundreds of amperes. Fault currents may be in the range of thousands, tens of thousands, or even hundreds of thousands of amperes. These very high currents cause extremely strong magnetic fields that can tear equipment apart when the currents pass through …

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Electrical Marking and Labeling

the NEC includes many requirements for the marking of various types of electrical equipment Equipment Manufacturer Markings and Labels Many of the codes requirements apply to markings or labels provided by the equipment manufacturer, such as electrical requirements for motors and appliances, or the ratings of devices such as switches and circuit breakers. Other equipment …

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lightning protection systems

The function of a lightning protection system is to protect structures from fire or mechanical destruction and persons in the buildings from injury or even death. Components of a lightning protection system : Air-termination systems Down conductors systems Earth-termination systems separation distances Lighining equipotential system A lightning protection system consists of an external and an …

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NEC Organization

The NEC is divided into an  introduction and nine chapters. Chapter 1: General includes : definitions of terms used throughout the Code the general conditions that apply to all installations. Chapter 2 : Wiring and Protection covers the general requirements for : branch circuits feeders services load calculations overcurrent protection grounding and bonding of equipment …

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Authority Having Jurisdiction (AHJ)

The authority having jurisdiction (AHJ) is defined as “An organization. office. Or individual responsible for Enforcing the requirements of a code or standard, or tor approving equipment, materials, an installation, or a procedure.“ Since Authority Having Jurisdiction (AHJ) and approval agencies vary. as do their responsibilities. Where public safety is primary. the authority having jurisdiction …

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what is a circuit breaker

Circuit breakers provide a manual means of energizing and de-energizing a circuit and automatic overcurrent protection

Switchboard Definition

The National Electrical Code® (NEC) defines a switchboard as a large single panel, frame, or assembly of panels on which are mounted, on the face, back, or both, switches, overcurrent andother protection devices, buses, and usually instruments. As this definition indicates, switchboards enclose various devices. For example, the following illustration shows two switchboard sections, an …

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what is Fuses ?

Device containing fusible link that protects electrical circuit from over current condition only Types of Fuses Cartridge Fuse Constructed with zinc or alloy fusible element Enclosed in cylindrical tube Element ends attached to metallic contact piece at ends of tube Normally used on circuits rated between 250 volts and 600 volts Maximum continuous current-carrying capacity …

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