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Fuses and NEC 2008 ChangesAuthor: Chris B Posted Date: 3/9/2010 5:09:56 PM
Recent catastrophic events like hurricane Katrina and 9/11 have made a lot of people take notice, especially those behind the National Electric Code. As part of a huge shift in focus toward life safety (like new AFCI/GFCI and tamper-resistant receptacle requirements), there have been a number of changes in regard to power devices. The events I mention above were monumental in drawing attention to the need for system load reliability. Whenever part of a building is damaged or failing, a key objective is clearly maintaining power to the "vitals" as long as possible.
This is where "selective coordination" comes into play. Selective coordination is the act of isolating a faulted circuit from the rest of an electrical system, which is the best way to eliminate unnecessary power outages. You do this by using overcurrent protective devices that have ratings and settings just like a particular overcurrent condition.
For your own reference, here's a quick list of applications where selective coordination is required per the NEC:
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Healthcare facilities, which have essential electrical systems like critical branches and life safety branches. (Article 517.26)
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Certain types of elevators (Article 620.62)
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Emergency systems in places where people frequently assemble, such as hotels, theaters, sports arenas, health care facilities, etc. (Article 700.27)
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Legally required standby systems, like those that serve loads in heating and refrigeration, smoke systems, communication systems, ventilation systems, sewage disposal, and other processes where any interruption would be hazardous. (Article 701.18)
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Critical Operations Power Systems with loads for communication and data centers. (Article 708.54)
I'll pick up next time with more detail on what selective coordination is, and what compliance means in light of NEC. Comments (1) | Leave Comments |  Permalink bussmann, fuses, selective coordination, applications, nec 2008, national electric code, power, safety
9/6/2010 7:29:24 PM
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