We will see how AC became the king of transmission and how DC, which many thought had met its demise, actually became the king of the appliance and equipment world; and how, while unknown to many, both types are used equally for the most part and have become close partners, sharing an almost symbiotic relationship with each other.
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Conductor sizes and overcurrent device ratings are critical to the safe, long-term operation of any electrical system, but are of particular importance in PV systems where the outdoor environment can be extreme and the PV modules will be sourcing current for 40 years or more.
(7 votes, average: 4.29 out of 5)
The Basics of Selective Coordination Merely having a higher ampere overcurrent protective device (OCPD) feeding a lower ampere overcurrent protective device does not assure a circuit is selectively coordinated. Designing a selectively coordinated system takes a knowledgeable person who is capable at the task and who has the necessary data available to select the proper [...]
(2 votes, average: 5.00 out of 5)
Selective coordination ensures proper isolation and localization for all possible overcurrents (from overloads to maximum short-circuit currents at the point of application) to the nearest upstream overcurrent protective device and prevents unnecessary loss of power to other loads, especially loads essential for life safety. The Code requires selective coordination for all supply-side overcurrent protective devices [...]
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Part I, which appeared in the March/April issue, provided readers with information about basic operation and basic time-current characteristics of branch-circuit, low-voltage fuses and circuit breakers. This article covers three overcurrent protective device ratings, their application in design, and NEC compliance aspects of low-voltage branch-circuit fuses and circuit breakers. These overcurrent protective devices (OCPDs) are [...]
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This article provides readers with essential information about basic operation and basic time-current characteristics of branch-circuit-rated, low-voltage fuses and circuit breakers. These overcurrent protective devices (OCPDs) are typically used in main service disconnects, feeders and branch circuits of residential, commercial, institutional, and industrial electrical systems. There are other OCPDs used, such as relays and supplementary [...]
(1 votes, average: 5.00 out of 5)
For certain vital circuits, the 2005 NEC requires that all overcurrent protective devices be selectively coordinated with all supply side overcurrent protective devices in the system. In addition, the definition for selective coordination has been added in Article 100. This commentary includes an overview of the requirements, what selective coordination means, the rationale for the [...]
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A significant and controversial change was made to 2005 NEC 240.86. This article is intended to provide electrical inspectors and others in the industry with background information and to explain how the new requirements in 240.86 can be met.
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The fundamental purpose of overcurrent protection is to protect conductors and equipment against the effects of excessive temperature on conductors and conductor insulation from overcurrent. Some of the issues we might not be fully familiar with are these: What devices are suitable for branch and feeder overcurrent protection? Matching device rating to system voltage Application [...]
(No Ratings Yet)One of the most fundamental elements of an electrical installation is the connecting of the wiring method to an overcurrent device. Seems simple right? All most people seem to do (including inspectors) is to look at Table 310.16 and match up the numbers to a fuse or breaker. Unfortunately the actual selection process can be [...]
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IAEI, as the keystone of the electrical industry, is a membership driven, non-profit association promoting electrical safety throughout the industry by providing premier education, certification of inspectors, advocacy, partnerships and expert leadership in Electrical Codes and Standards development.
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