Cable Ampacity Software - NEC Standard
The NEC standard uses the NFPA 70 method and applies to aboveground cables. The derated cable ampacity calculation is based on the parameters listed here below.
Cable Raceway Installations
- A/G Conduit
- A/G Trays
- Air Drop
Tray Configuration Options
The method applied by the cable ampacity simulation software tool corresponds to a maximum fill condition and does not consider fill conditions exceeding the nominal depths.
- Top Covered tray
- Cables kept with Maintained Spacing
The cable ampacity simulation tool calculates the derated ampacity based on the ambient and conductor temperatures. In addition, the user can either select the base temperature provided by the manufacturer or the operating temperature of the cable.
- Base Ambient Temperature
- Base Conductor Temperature
- Operating Ambient Temperature
- Operating Conductor Temperature
Cable Fire Protection
In this cable ampacity training module, you can select from a variety of fire protection layers available in the ETAP Library. ETAP’s ampacity training software lets you define the following cable fire protection parameters:
- Cable Thermal Insulation
- Cable Insulation Length of able thermal insulation
Alert for Allowable Ampacity
ETAP provides alerts to the user when a critical situation occurs such as overloading. A critical situation may deteriorate the cable and tremendously reduce its lifetime. The alerts tool of the cable ampacity study software is based on the options listed below.
- Based on the calculated Derated Ampacity
- User-Defined value
- Based on thermal analysis results of underground raceway systems module
This cable ampacity analysis program calculates derating factors for cable trays according to NEC. The cable ampacity analysis software applies to cables in above ground trays, conduits, and air drop. The NEC Standard does not provide cable ampacity derating due to bottom cover or correction of the cable ampacity multiplying factors due to the cumulative effects of combinations of tray covers and fireproofing. In general, cable sizes of 2/0 AWG and smaller are installed in cable trays in a randomly filled manner, with a maximum of two cables high.
Base cable ampacity of randomly filled trays are based on installations at a uniform depth up to the maximum of 30% fill for 3 or 4-inch tray depths. The cable ampacity assessment tool applied here corresponds to a maximum fill condition and does not consider fill conditions exceeding the nominal depths.
For NEC standard, the selected cable Base ampacity must be in accordance with the cable ampacities listed in the tables from NEC Article 310.