A Study Of The Fire Performance Of Electrical Cables

Abstract

Experimental results are presented of the piloted ignition delay time and the upward flame-spread rate over the surfaces of insulated electrical cables under an externally applied radiant flux. The objective of the experiments was to assess and rank the fire performance of seven types of complex cables commonly used in electrical installations. The experiments were carried out with 46 em long single cables that were suspended vertically and exposed to irradiance levels ranging from 0.5 -2.5 W/cm 2 • Some of the cables had a conducting core, and some did not. A simplified analysis, similar to that developed by Quintiere and coworkers was developed to indentify the parameters that dominate the fire characteristics of the cable. A method similar to that proposed by the above authors was applied to develop flammability diagrams and to define the flame spread properties of the cable materials in an attempt to assess and rank the fire performance of the seven types of cable. It is shown that the method can be successfully applied and that it provides a simple way to rank the cables and to calculate the parameters important to ignition and flame spread in electrical cables. The study also explores the feasibility of predicting the piloted ignition performance of the cable insulations using thermogravimetric analysis (TGA) data in conjunction with the ignition and flame spread formulas by proposing that the surface temperature at which thermal degradation produces pryolyzate is related to the ignition temperature for that particular material. The predicted ignition delay times are compared with experimental results and it is shown that for most polymers, the temperature at which thermal degradation is first Observed can be used to estimate ignition delay times, particularly at high irradiance levels.

Ignition and Flame Propagation of Externally Heated Electrical Wires with Electric Currents

“…The flame propagation test of electrical wires at inclination was studied in NASA's standard test [6]. Fernandez-Pello et al [7] experimentally studied the fire performance of several electrical wires and predicted their ignition delay time theoretically. Leung et al [8] simulated the effect of the central core on thermal pyrolysis of the insulation layer without flame during the heating process.…”

High‐throughput method for estimating the time to sustained ignition of polystyrene–clay nanocomposites based on thermogravimetric analysis

“…Previous reports21, 22 showed that TGA is a feasible tool for predicting, fairly accurately, the time to ignition for pure polymers. Briefly, in both these studies, the TGA was preheated to a given temperature and the sample was inserted and heated isothermally.…”

“…Briefly, in both these studies, the TGA was preheated to a given temperature and the sample was inserted and heated isothermally. The second inflection of the temperature–time curve21 or the initiation of the weight loss temperature22 (defined by the authors as the temperature at which the mass loss curve separates from the zero weight loss position and assumed to be the same as the ignition temperature) was recorded. Further, the value of this characteristic temperature was plugged into the flame‐spread equations and the time to ignition was calculated.…”

“…However, no correlation to cone calorimetry experiments was made. Using similar isothermal heating programs, Fernadez‐Pello et al 22. explored the feasibility of predicting the piloted ignition performance of cable insulations using TGA data in conjunction with the ignition and fire spread formula.…”

Experimental and Numerical Studies on Major Pyrolysis Properties of Flame Retardant PVC Cables Composed of Multiple Materials

“…Fire spread rate prediction is critical for fire risk assessment and fire safety design, and numerous studies have been conducted on the spread of fire in buildings over the last few decades [1]. In particular, the electrical cables used for various elements in housing and industrial environments pose a constant risk of electrical fires, which account for the largest portion of fires, and the cables themselves can act as ignition sources, inducing large-scale fire or secondary combustibility [2]. As an applied example of electric-cable-induced fire, research on ignition and fire spread due to cable malfunction has been conducted under special conditions such as the microgravity environment of a space station [3,4].…”