Charles R. Miller

Code Contributor

Charles R. Miller, owner of Lighthouse Educational Services, teaches classes and seminars on the electrical industry. He is the author of “Illustrated Guide to the National Electrical Code” and NFPA’s “Electrical Reference.” He can be reached at 615.333.3336, charles@charlesRmiller.com or www.charlsRmiller.com

Articles by Charles R. Miller

December 2013
Tap conductor rules are located in Article 240 in the National Electrical Code (NEC). A tap conductor (as used in Article 240) has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4 [240.2]. Also, service conductors are not tap conductors.
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November 2013
transformer secondary conductor rules are similar to tap conductor rules. Article 240.21 of the National Electrical Code (NEC) covers the location and sizing requirements of overcurrent protection for tap conductors and transformer secondary conductors. READ MORE
October 2013
Article 240 in the National Electrical Code (NEC) is titled “Overcurrent Protection.” While this term is not defined, Article 100 defines overcurrent. Overcurrent is any current in excess of the rated current of equipment or the ampacity of a conductor. The definition also states overcurrent may result from overload, short circuit or ground fault. READ MORE
September 2013
There is more to sizing a conductor than just selecting a conductor from Table 310.15(B)(16) (formerly Table 310.16) in the National Electrical Code (NEC). READ MORE
August 2013
Section 240.21 in the National Electrical Code (NEC) contains feeder tap rules. As defined in 240.2, a tap conductor has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4. READ MORE
July 2013
Table 310.15(B)(16) is one of the most referenced tables in the National Electrical Code (NEC). It contains allowable (or maximum) ampacities for insulated conductors rated up to and including 2,000 volts (V). The ampacities listed in this table are based on specific conditions.
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June 2013
As a general rule in the National Electrical Code (NEC), the ampere rating of the overcurrent device (fuse or breaker) must not be less than the ampacity of the conductor. READ MORE
May 2013
The overcurrent device rating is a key factor when determining the correct size conductor. Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices. READ MORE
April 2013
Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices. READ MORE

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