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[1]  Introduction

[2]  Calculation of Higher Ampacities for 0-2000 Volt Cables

[3]  Does the NEC Code Allow Alternate Ampacity Calculations?

[4]  Determining the Effects of Application Factors Not Accounted For in the Code

[5]  Organization and Reporting of Circuit Ampacities

[6]  Calculated Ampacities and Local Governing Authorities


Aerial Ampacity Calculations and the NEC Code

 [Last]  Page 6 of 6

Calculated Ampacities and Local Governing Authorities

The legitimacy of utilizing Neher-McGrath calculation procedures to provide cable ampacity ratings for aerial cable systems has been clearly demonstrated. These calculation procedures are recognized by industry standards and practices, and are in fact utilized in most of the NEC Code ampacity tables.

Nevertheless, it must be recognized that local governing authorities and inspectors may require strict adherence to the ampacities contained in Tables 310.16 or 310.17, regardless of what accepted industry calculations may establish. Consequently, serious attention must be given to this consideration when determining the basis for aerial system ampacities for a given project.

However, even where adherence to the Code Tables 310.16 and 310.17 is absolutely required by the local governing authorities, the calculations can still often be utilized to address special concerns the authorities may have which are not addressed in the Code. For example, the effect on cable ampacities by the use of fireproofing insulation applied to electrical conduits.

 [Last]  Page 6 of 6


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