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 …
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 …
A TT system, has the neutral of the source of energy connected as for TN-S, but no facility is provided by the distributor for the consumer’s earthing. With TT, the consumer must provide their own connection to earth, i.e. by installing a suitable earth electrode local to the installation.
A TN-C-S system, has the supply neutral conductor of a distribution main connected with earth at source and at intervals along its run.This is usually referred to as protective multiple earthing (PME). With this arrangement the distributor’s neutral conductor is also used to return earth fault currents arising in the consumer’sinstallation safely to the source. …
A TN-S system has the neutral of the source of energy connected with earth at one point only, at or as near as is reasonably practicable to the source and the consumer’s earthing terminal is typically connected to the metallic sheath or armour of the distributor’s service cable into the premises or to a separate …
Commercial and industrial distribution systems use various methods to conduct electrical energy. These methods often include heavy conductors run in trays or conduit. Cable and conduit assemblies are costly and time consuming to install. Once installed, they are difficult to change. To eliminate these shortcomings, power is often distributed using enclosed bus bars. This is …
A power distribution system is a group of components that carries electrical power throughout a building. Distribution systems are used in every residential, commercial, and industrial building. Distribution systems used in commercial and industrial locations are complex. They include metering devices to measure power consumption, main and branch disconnects, protective devices, switching devices to start …