Vytenis (Vyto) Babrauskas, Ph.D.
\nFire\u00a0Science and Technology Inc., Issaquah WA<\/p>\n
Presented at\u00a0International Symposium on Fire Investigation<\/a>, 2014<\/p>\n ABSTRACT Keywords : dielectric strength of cables; electrical fires; forensic failure analysis; electrical installation defects; NM\u00a0cables; voltage surges.<\/p>\n Download the complete paper<\/a> here<\/p>\n","protected":false},"excerpt":{"rendered":" Vytenis (Vyto) Babrauskas, Ph.D. Fire\u00a0Science and Technology Inc., Issaquah WA Presented at\u00a0International Symposium on Fire Investigation, 2014 ABSTRACT A significant fraction of US structure fires originate in electrical wiring, and there is also reason to believe that these\u00a0numbers may be systematically undercounted. The role of voltage surges and damaged insulation in creating the\u00a0potential for fire … Continue reading Fires Originating in Branch-Circuit NM Cables Due to Installation Damage<\/span>
\nA significant fraction of US structure fires originate in electrical wiring, and there is also reason to believe that these\u00a0numbers may be systematically undercounted. The role of voltage surges and damaged insulation in creating the\u00a0potential for fire is discussed. That damaged electrical insulation may lead to fire has been known for a century, yet\u00a0details of the mechanisms by which this occurs have not been extensively studied. UL recently published a study on\u00a0damage due to poor workmanship in stapling of cables, specifically cases where the insulation is damaged but the\u00a0conductors are not split. This study establishes that damage which may not appear visually striking may result in\u00a0dielectric failure; such failures can be a direct cause of fire. Case histories are presented illustrating how mechanical\u00a0damage associated with stapling of NM cables can result in serious fires. Two preventive measures are described:\u00a0(a) installation by use of staplers and not hammers, and (b) testing the dielectric withstand voltage of branch circuits\u00a0after installation and prior to energizing. Both of these measures, if implemented, should reduce the prevalence of\u00a0electrical fires. However, given the immense amount of fixed wiring installed in buildings, fires due to damaged\u00a0insulation do not imply that current wiring methods are a low-reliability technology. Only when serious installation\u00a0defects are present does fire become a foreseeable event.<\/p>\n