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UL 1724 OUTLINE

Outline of Investigation for Fire Tests for Electrical Circuit Protective Systems

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Organization: UL
Publication Date: 7 December 2006
Status: active
Page Count: 34
scope:

These requirements cover the fire test investigation of electrical circuit protective systems of various materials and construction.

Under these requirements, samples of electrical circuit protective systems are exposed to an external fire for a predetermined time, and then to an application of a water hose stream. The following measurements and determinations are made during the fire exposure and water hose stream tests:

a) Measurement of temperature changes within the electrical circuit protective system caused by the heat transfer through the electrical circuit protective system to the electrical conductor or raceway, or both, during the external fire exposure test.

b) Determination of the integrity of the electrical circuit protective system during the external fire exposure and water hose stream test.

c) Determination of the ability of insulated electrical conductors to maintain electrical circuit integrity at the temperature conditions present within the electrical circuit protective system during the external fire exposure test and during the water hose stream test.

The external fire exposure and water hose stream test may be cited as the "Standard Fire Test," and the performance is expressed in terms of maximum temperature rise within the electrical circuit protective system at various increments of fire exposure time.

The external fire exposure and water hose stream tests may not be representative of all fire conditions; conditions may vary with changes in the amount, nature, and distribution of fire loading, ventilation, compartment size an configuration, and heat conducting and dissipating characteristics of the compartment in which the electrical circuit protective system is installed. These requirements provide a relative measure of fire performance of comparable assemblies under these specified fire exposure conditions. Any variation from the construction or operating condition tested, such as size, method of assembly, and materials, may substantially change the performance characteristics of the system.

These requirements also cover sample systems which are subjected to an internal fire exposure to evaluate their ability to contain fires originating within the electrical circuit protective system if, for example, the system contains ventilation means such as holes, slots, louvers, or dampers. The internal fire exposure test may be waived at the discretion of the testing body if the material or installation, or both, obviate the need for such testing.

These requirements do not cover:

a) Accumulation of data as to performance of electrical circuit protective systems constructed with components or sizes other than those tested.

b) Evaluation of the contribution of the electrical circuit protective systems to generation of smoke, toxic gases, or other products of combustion.

c) Measurement of flame spread over the surface of the tested elements.

d) Evaluation of the firestop system in floor openings penetrated by the electrical circuit protective systems, unless specifically provided for in the system tested.

e) Evaluation of the ampacity of electrical conductors within the electrical circuit protective systems.

The results obtained by use of this test method are intended to develop data that will assist authorities having jurisdiction, and others, in determining the acceptability, with reference to circuit integrity, of electrical circuit protective systems for use with specific electrical conductors in specific applications.

Tests for burning characteristics of building materials, based on rate of flame spread and the density of smoke developed when exposed to a standard fire, can be found in the requirements for surface burning characteristics of building materials, UL 723.

Tests for fire resistance of firestop systems which penetrate through walls and floors can be found in the requirements for Through-Penetrate Firestop Systems, UL 1479.

By the prescribing of the standard fire and water hose stream exposures for comparing the performance of electrical circuit protective systems, the results of these tests represent one factor in determining the acceptability, with reference to circuit integrity, of electrical circuit protective systems for use with specific electrical conductors in specific applications. Application of these test results to predict circuit integrity of electrical conductors in actual installations requires careful evaluation of the electrical conductor insulation materials and the temperature within the electrical circuit protective system under normal operating conditions.

Document History

UL 1724 OUTLINE
December 7, 2006
Outline of Investigation for Fire Tests for Electrical Circuit Protective Systems
These requirements cover the fire test investigation of electrical circuit protective systems of various materials and construction. Under these requirements, samples of electrical circuit...
August 1, 1991
Outline of Investigation for Fire Tests for Electrical Circuit Protective Systems
A description is not available for this item.

References

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