Standard Procedure for the Determination of the Ampacity Derating Factor for Fire-Protected Cable Systems
|Publication Date:||16 February 2015|
This standard provides a test procedure for determining the ampacity derating factor in the following cable installation configurations:
- Block-out or sleeve-type cable penetration fire stops
- Conduits covered with a protective material
- Trays covered with a protective material
- Cable directly covered or coated with a fire-retardant material
- Free-air drops enclosed with a protective material
The standard is applicable to cables installed and sized to IEEE Std 835™ for conduits and free-air drops, and NEMA WC51/ICEA P-54-440 for cable tray.1 IEEE Std 135™ does provide ampacities for cables in a tray with a fixed spacing and may be used for cable penetration fire stop configurations only.
This standard does not endorse the use of or provide application guidance for the installation of cable penetration fire stops and fire-protective materials. Cable designs are available that can withstand and remain functional during direct exposure to a fire. The user should refer to IEEE Std 634™ for the qualification requirements of cable penetration fire stops.
The purpose of this standard is to provide a test procedure for use in establishing the ampacity derating factor for cables installed in fire-protected conduits, trays, free-air drops, cable penetration fire stops, or electrical separation wrap systems.
1 Information on references can be found in Clause 2.