Training - Webinar
Please note that this webinar has changed from June 27th to June 28th
Date: Wed, June 28, 2018 12:00 PM - 1:00 PM EDT - REGISTER
Presenter: Jason D’Ornellas, P.Eng., Consulting Electrical Engineer and Managing Partner of Fire Investigation at Roar Engineering
Title: Arc Mapping, one of the four sources of information in Origin Determination
Join Jason D’Ornellas, Electrical Engineer and Managing Partner at Roar Engineering in a review of the techniques of arc mapping, with case studies, utilizing arc mapping in fire investigations.
According to NFPA 921, Arc mapping is one of the four methodologies in Origin Determination. If used correctly in a fire investigation, arc mapping is an excellent alternate source of data for origin determination independent of, and complementary to fire pattern analysis. NFPA 1033, – Standard for Professional Qualifications for Fire Investigator requires that a “fire investigator remain current” in the 16 topics listed in the standard, which includes Fire investigation, Fire investigation methodology, and Electricity and electrical systems. Arc Mapping is part of these three topics which the fire investigator shall know and be able to utilize in fire investigations. Arc Mapping is an excellent source of origin data when a room has reached flashover where fire patterns indicating an origin have been masked or obliterated by subsequent patterns and burning during the course of the fire.
When energized electrical circuits, such as conventional house wiring or wiring in appliances or vehicles, are attacked by a spreading fire, they may leave behind evidence of electrical arcing activity. This will be in the form of localized melting of copper or aluminum conductors, localized melting of an adjacent steel enclosure from electrical arcing, arc-severed conductors, and arc splatter. Arc mapping, or arc surveys, is a method used by fire investigators to document and analyze the locations of electrical arcing sites relative to each other and to the source of the power supply.
The methodology is based on predictable behaviour. Typically, the plastic insulation on the conductors for the section of the wiring first attacked by the fire will char, which will make the insulation semi-conductive. Electricity flowing through the charred insulation will generate heat. The heat will cause localized melting, or arcing, on the conductors. Eventually, the circuit protection, a fuse or a breaker at the source of the circuit will trip, or open, stopping the flow of electricity and any electrical arcing, leaving behind the recognizable evidence of the electrical arc sites where the fire first attacked the wiring.