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

February 2013
The rating of the overcurrent device must be considered when sizing a conductor. In accordance with 240.4 in the National Electrical Code (NEC), conductors (other than flexible cords, flexible cables and fixture wires) shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G).
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January 2013
Table 310.15(B)(16) (formerly Table 310.16) in the National Electrical Code (NEC) provides allowable ampacities for insulated conductors rated up to and including 2,000 volts (V). The ampacities in this table are based on no more than three current-carrying conductors in a raceway, cable or earth (directly buried). The ampacities are also based on an ambient temperature of 30°C. 
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December 2012
Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices. When sizing conductors, the rating of the overcurrent device must be considered. READ MORE
November 2012
When sizing conductors, more is involved than just selecting a copper or aluminum conductor with the right ampacity from Table 310.15(B)(16) (formerly Table 310.16) in the National Electrical Code (NEC). Conductors must be selected and installed in accordance with all applicable provisions pertaining to conductors. READ MORE
October 2012
Table 310.15(B)(16) is one of the most referenced tables in the National Electrical Code (NEC). It provides allowable ampacities for insulated conductors rated up to and including 2,000 volts (V). The ampacities listed in the table are based on an ambient temperature of 30°C and on no more than three current--carrying conductors in a raceway, cable or earth (directly buried). READ MORE
September 2012
When sizing conductors, the rating of the overcurrent device must also be considered. In accordance with 240.4 in the National Electrical Code (NEC), conductors (other than flexible cords, flexible cables and fixture wires) shall be protected against overcurrent in accordance with their ampacities specified in 310.15, unless otherwise permitted or required in 240.4(A) through (G). READ MORE
August 2012
Table 310.15(B)(16) in the National Electrical Code (NEC) provides allowable or maximum ampacities for insulated conductors rated up to and including 2,000 volts (V). When sizing conductors, more is involved than just looking in Table 310.15(B)(16) and selecting a conductor based on the ampacity shown. READ MORE
July 2012
Ambient temperature and the number of current-carrying conductors installed in a raceway or cable are two factors to consider when sizing conductors. In accordance with 310.15(A)(3) in the National Electrical Code (NEC), no conductor shall be used in such a manner that its operating temperature exceeds the limit designated for the type of insulated conductor involved. READ MORE
June 2012
When sizing conductors, more is involved than just looking at Table 310.15(B)(16) in the National Electrical Code (NEC) and selecting a copper or aluminum conductor with the right ampacity. Of all the tables in Article 310, Table 310.15(B)(16) is referenced the most. READ MORE

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