Centro de Documentação da PJ
Monografia
 CD258 |
Development and analysis of electrical receptacle fires [Documento electrónico] / Matthew E. Benfer, Daniel T. Gottuk.- [Rockville, MD] : National Criminal Justice Reference Service (NCJRS), 2013.- 1 CD-ROM ; 12 cm
Research report submitted by Hughes Associates to the U.S. Department of Justice. NIJ Award Number: 2010-DN-BX-K218. Ficheiro de 4,21 MB em formato PDF (346 p.).
ANÁLISE DE VESTÍGIOS, INCÊNDIO
Executive summary. 1.0 Introduction. 1.1 Literature review. 1.1.1 Codes and standards. 1.1.2 Arcing. 1.1.2.1 Arc tracking. 1.1.3 Receptacle and plug connections. 1.1.3.1 Overheating receptacle connections. 1.1.3.2 Other glowing connections. 1.1.3.3 Screw terminal torque. 1.1.3.4 Back wired push-in connections. 1.1.3.5 Overheating plug connections. 1.1.4 Arcing and overheating connections as competent ignition sources. 1.1.5 Forensic examination of electrical components. 1.1.6 Aged receptacles. 1.2 Motivation for testing. 1.3 Objectives. 1.4 Experimental approach. 1.4.1 Experimental variables. 1.4.2 Key test variables.1.4.2.1 Screw terminal torque.1.4.2.2 Receptacle material.1.4.2.3 Outlet box and faceplate materials.1.4.2.4 Plug type.1.4.3 Receptacle serial number.2.0 Laboratory testing of receptacles.2.1 Experimental design.2.1.1 Test rack construction. 2.1.1.1 Vibration. 2.1.2 Receptacle installation. 2.1.2.1 Screw terminal tightening. 2.1.2.2 Back wired push-in connections. 2.1.2.3 Nominal plug connection retention force. 2.1.3 Electrical power and load. 2.1.4 Instrumentation. 2.1.5 Data acquisition. 2.2 Experimental procedures. 2.2.1 Receptacle installation procedures. 2.2.2 Test procedures. 2.3 Experimental results and analysis. 2.3.1 Formation of overheating connections at receptacle terminals. 2.3.1.1 Screw terminal torque. 2.3.1.2 Back-wired push-in connections. 2.3.1.3 Plug connections. 2.3.2 Mechanisms for overheating. 2.3.2.1 Oxidation. 2.3.2.2 Corrosion. 2.3.3 Effects of overheating. 2.3.3.1 Receptacle material behavior. 2.3.3.2 Temperature rise and voltage drop. 2.3.3.3 Glowing connections. 2.3.3.4 Enlarged screw heads. 2.3.4 Receptacle and plug failures. 2.3.4.1 Flaming ignition. 2.3.5 Evidence of failure events at screw connections. 2.3.5.1 Arcing. 2.3.5.2 Welded conductors from glowing connection. 2.3.5.3 Enlarged screw head. 2.3.5.4 Severed conductor ends. 2.3.6 Evidence of failure events for plug connections. 2.3.7 Test variable effects on receptacle failures. 2.3.7.1 Primary receptacle material. 2.3.7.2 Surrounding materials. 2.3.7.3 Installation, use, and abuse. 3.0 Fire exposure testing.3.1 Experimental design. 3.1.1 Compartment fire tests. 3.1.1.1 Compartment fire configuration. 3.1.1.2 Wall assembly construction. 3.1.1.3 Receptacle power. 3.1.1.4 Extension cord installation. 3.1.1.5 Instrumentation. 3.1.1.6 Data acquisition. 3.1.2 Intermediate scale furnace testing. 3.1.2.1 Furnace description/construction. 3.1.2.2 Wall assembly construction. 3.1.2.3 Instrumentation. 3.1.2.4 Plug installation. 3.1.2.5 Data acquisition. 3.2 Experimental procedures. 3.2.1 Compartment fire testing. 3.2.1.1 Test procedures. 3.2.1.2 Sample recovery procedures. 3.2.2 Intermediate scale furnace testing. 3.2.2.1 Test procedures. 3.2.2.2 Removal and sample recovery procedures. 3.2.3 Forensic examination. 3.2.3.1 Receptacle examination. 3.2.3.2 Scanning Electron Microscopy (SEM). 3.2.3.3 Polishing and sectioning. 3.2.3.4 FTIR analysis. 3.3 Experimental results and analysis. 3.3.1 Thermal damage characterization. 3.3.1.1 Thermal insult. 3.3.2 Receptacle thermal damage. 3.3.2.1 Polypropylene receptacles. 3.3.2.2 PVC receptacles. 3.3.2.3 Thermoset receptacles. 3.3.3 Faceplate Thermal damage. 3.3.3.1 Nylon faceplates. 3.3.3.2 Steel faceplates. 3.3.4 Outlet box thermal damage. 3.3.4.1 PVC outlet boxes. 3.3.4.2 Steel outlet boxes. 3.3.5 Assessing the fire environment from thermal damage. 3.3.6 Melting of metal receptacle components and wiring. 3.3.6.1 Characteristics of melting for brass and copper receptacle components. 3.3.6.2 Thermal exposures for melting of brass and copper receptacle components. 3.3.7 Arcing damage. 3.3.7.1 Arcing damage location. 3.3.7.2 Characteristics of arcing. 3.3.7.3 Thermal insult. 3.3.8 Arc fault current analysis. 3.3.8.1 Screw terminal loosening torque. 3.3.8.2 Plug blade retention force. 3.3.9 Persistence of damage from overheating connections after fire exposure. 3.3.9.1 Welded conductors. 3.3.9.2 Enlarged screw heads. 3.3.9.3 Evidence of arcing. 3.3.9.4 Severed conductors. 3.3.9.5 Severe oxidation. 4.0 Distinguishing arc from melt damage. 4.1 Corresponding damage on the opposing conductor. 4.2 Localized point of contact with a sharp line of demarcation. 4.3 Round, smooth shape. 4.4 Resolidification waves. 4.5 Tooling marks visible outside area of damage. 4.6 Internal porosity. 4.7 Spatter deposits. 4.8 Small beads and divots over a limited area. 4.9 Indicators of melting. 4.9.1 Visible effects of gravity. 4.9.2 Gradual necking of conductor. 4.9.3 Pitting, thinning, and presence of holes. 4.10 Summary of arcing and melting damage and identification. 4.11 Case study: distinguishing arc from melt damage using SEM/EDS. 5.0 Summary of findings. 6.0 Conclusions. 6.1 Overheating connections. 6.2 Fire damage to receptacles and plugs. 6.3 Arcing and melting damage examination. 6.4 Implications for policy and practice. 6.5 Implications for further research. 7.0 References.