Impact of Flashover Fire Conditions on Exposed Energized Electrical Cords/Cables

Abstract

There has been prior research exploring the exposure of common electrical cords and cables to fire, but that has traditionally been at the lab scale and under near steady-state exposures. The goal of these experiments was to expose six types of cords and cables in a room-scale compartment with a fuel load sufficient to drive the compartment through flashover. The basic test design was to expose the cords and cables on the floor of a compartment to a growing fire to determine the conditions under which the cord/cable would trip the circuit protection device. All of the cords were energized and installed on a non-combustible surface. The six cables and cords were protected by three different circuit protection devices which were remote from the thermal exposure. This configuration resulted in 18 exposures per experiment. The room fires experiments consisted of three replicate fires with two sofas as the main fuel source, two replicate fires with one sofa as the main fuel source and one fire with two sofas and vinyl-covered MDF paneling on three walls in the room. Each fuel package was sufficient to support flashover conditions in the room. The average peak heat release rate of the sofa fueled compartment fires with gypsum board ceiling and walls prior to suppression was 6.8 MW. The addition of vinyl covered MDF wall paneling on three of the compartment walls increased the pre-suppression peak heat release rate to 12 MW. In each experiment during post flashover exposure, the insulation on the cords and cables ignited and burned through, exposing bare wire. During this period, the circuits faulted. Assessments of both the thermal exposure and physical damage to the cords did not reveal any correlation between the thermal exposure, cord/cable damage, and trip type.

Quantification of Elevated Hydrogen Cyanide (HCN) Concentration Typical in a Residential Fire Environment Using Mid-IR Tunable Diode Laser

“…This fuel was characterized in a previous laboratory study and the total energy release was measured to be 650 MJ with the peak heat release rate of 4.2 MW. 39

Figure 5.Plan (top panel) and front elevation (bottom panel) of the FES prop. HCN is measured in exposure chamber 2 at 0.3 m (green), 0.9 m (blue), and 1.5 m (red).

…”

“…This fuel was characterized in a previous laboratory study and the total energy release was measured to be 650 MJ with the peak heat release rate of 4.2 MW. 39 Each 15-minute experiment starts with 2 minutes of background gas sampling before ignition of the sofa with a road flare. All the doors are kept closed and the fire is allowed to grow utilizing only the leakage paths in the combustion chamber for ventilation.…”

Potential Method to Distinguish Copper Molten Marks Using Boundary and Grain Characteristics

“…At this stage, the probability of a wire short-circuit increases. In addition, Weinschenk et al [16] reported that within 2 min of applying a flame, the temperature started to rise, and over-current faults or grounding faults occurred; the ambient temperature at this time was approximately 900 • C. Based on these two reports, the temperature of the copper wires was maintained at 600 • C and 900 • C for 2 min, and SAB-600 and SAB-900 were then, respectively, produced by inducing a short circuit. After that, the temperature was maintained for 5 min.…”

Heat Release Rate Characterization of NFPA 1403 Compliant Training Fuels

“…The fuel load in a typical residential room would often consist of more than a single item of furniture. Experiments conducted by Weinschenk et al examined the HRR of a 3.65 m  3.65 m room furnished with two upholstered sofas, carpet, and carpet padding [28]. Each of these rooms transitioned through flashover, with peak HRRs ranging from 6.2 MW to 7.0 MW.…”