Fire / Flame Tests and Ratings

UL Vertical Tray Flame Test
UL 1581

The test is conducted on cables lashed to a vertical metal ladder tray 8 feet in height.  The combustion source is a ribbon burner with a flame temperature of approximately 1,500o F and which supplies 70,000 BTU's of heat per hour.  The flame application time is 20 minutes.  This rating requires to the cable to self-extinguish prior to reaching the top of the tray.  A 'tray rated' cable must meet this test.  The IEEE 383 test is similar in nature.

UL VW-1 Vertical-Wire Flame Test
UL 1581

This is a small-scale test conducted on a single 24 inch length of wire.  The flame source is a Tirrill burner (similar to a Bunsen Burner) with a heat output of approximately 3,000 BTU/hour.  The flame is applied for 15 seconds and is then reapplied 4 more times each time the wire ceases to burn.  If the sample burns longer than 60 seconds after any application, or if the indicator flag or cotton batting is ignited during the test, the cable fails the test.  The CSA FT-1 test is very similar.

IEEE Vertical Wire Flame Test
IEEE 383

Cables Essential for Emergency Operations in Nuclear Power Plants

The institute of Electrical and Electronic Engineers (IEEE) has established IEEE-383, "IEEE Standard for Type Test of Class IE Electric Cables, Field Splices and Connections for Nuclear Generation Stations".  Originally this specifications was intended for cables essential for emergency operations in nuclear power plants, this test procedure is now commonly used for other non-nuclear installations.

In the IEEE_383 fire test, cables are supported by a one foot wide vertical rack eight feet high.  The cables are positioned in the center six inches of the rack, spaced one-half cable diameter apart.  The rack is centered in an eight foot cube enclosure recommended by Underwriters' Laboratories.  A ten inch ribbon burner fuel with an air-propane mixture ignites the cable with a 21K W (70,000 BTU/hr) flame.  The burner is positioned 2 feet above the floor and 9 to 12 inches of cable are exposed to the direct flames for 20 minutes.  Cables on which flame extends above the top of the 8 foot rack fail this test.

CSA FT-1 Vertical Flame Test
CSA C22.2 No. 0.3, Section 4.11

In this test, cables are subjected to five 15-second duration applications of a 500 watt (3,000 BTU/hour) flame.  For the cable to pass the test, burning must cease within 60 seconds after removal of the flame source, and not more than 25% of the indicator flag can be burned.  This is similar to the UL VW-1 test.

CSA FT-1 Vertical Flame Test
CSA C22.2 No. 0.3, Section 4.11

In this test, cables are subjected to a 30 second application of a flame from a 500 watt source.  The cable must self-extinguish after removal of the flame source and must not ignite cotton batting placed under the cable.