HEATING METHOD CAN PLAY ROLE IN FIRE
BY RONALD J. RAKOSNIK
On Sunday, December 27, 1998, at 3:20 p.m., the Lombard (IL) Fire Department responded to a reported house fire in the northern part of town. Three engines, one tower ladder, two paramedic units, and two chief officers responded.
Deputy Chief Jerome Tonne, first to arrive on the scene, reported a large 212-story frame, single-family residence with fire on the first and second floors. Heavy, dark brown smoke was emanating from the siding on the east and west sides of the structure. After the initial size-up, Engine 45, the first engine on-scene, initiated a reverse lay, dropped both of its skids at the building, and connected to a water source. Each skid consists of a three-inch supply line and a 212- to 134-inch gated wye with two 134-inch attack handlines.
Tower Ladder 52 arrived and laddered the building. Its crew immediately went to the roof to provide vertical ventilation. When that was completed, the crew moved to the east side of the building and began removing the siding, checking for extension. Inside crews had knocked down the fire and were now performing overhaul. The majority of the fire had been knocked down.
INVESTIGATION
The single-family residence was built approximately 110 years ago. The house had been remodeled with two additions. The construction type in the older section is balloon construction. The heating system is a steam-type heat consisting of a boiler, piping, and various radiators. The boiler heats the water to form steam. The steam travels the pipes to the radiators, eventually condensing and draining back to the boiler.
The area of fire origin was determined to be in the basement ceiling. This area involved a chimney for the boiler, a hot water heater, steam pipes, an electrical conduit, and an electrical junction box. The fire traveled to the upper floors through the pipe chases, primarily the chase that housed the two-inch steam pipe.
The owner stated that “for the past three weeks they had had lights flickering at times,” but it did not appear to be a real concern.
Two-by-eight floor joists in the area of the steam pipe had split over the years. This was believed to have been caused by pyrolysis. The floor joists appeared to be old rough sawn type wood. The owner tried to repair them by using metal joist hangers and additional wood nailed to the existing joists.
The brick chimney used for exhausting the gases from the gas boiler and gas hot water heater was next to be examined. The chimney was examined inside, by use of a mirror, and outside. There was no sign of heat leakage.
The electrical junction box was the next item to be examined. The junction box was mounted on the ceiling between the floor joists, next to the two-inch steam pipe with little to no clearance. When the cover to the junction box was removed, two 212-inch screws that held the box to the ceiling fell out.
Fire damage in this area indicated that the fire in the ceiling traveled the pipe chases, igniting structural members in its path.
DETERMINATIONS
Steam pipes reached a temperature in the area of 2307F. The steam pipe had been radiating heat to the rough sawn floor joists and the plywood flooring for many years, causing the wood to pyrolyze. The continuous baking of wood caused pyrolysis, resulting in carbonization of the lumber. Common building material lumber has an ignition temperature of between 4007F and 6007F. The type of wood and the continuous amount of heat to this area over the long term dried out the wood, reducing its ignition temperature.
The close proximity of the steam pipe to the electrical junction box radiated and conducted heat to a point where the insulation on the wires inside the box broke down and began to arc. The electrical box was poorly grounded or not grounded at all. The conduit connected to the box was loose at each connection, thus the breaker panel would not sense a direct short. Therefore, it would not trip the breaker. The electrical box continued to arc, causing heat, which ignited the wood. The mounting screws for the electrical box pyrolyzed the wood, causing the wood around the screws to decompose, resulting in the loosening of the screws.
The fire was ruled electrical in origin, although the steam pipes played a major role in causing the fire. It should also be noted that the electrical work done in this residence was poor and most likely was not done during the winter months. The heat from the steam pipes during the heating season would have prevented the electrician from installing the box in that location.
POINTS TO REMEMBER
Steam heat is not commonly found in today`s residential structures. Investigators must be aware of the type of heat and the effect it may have on the origin and cause of a fire.
Electrical work should be done by a licensed electrician, and the appropriate permits should be filled out. If this were done in this case, the electrical inspector may have determined the close proximity of the junction box to the steam pipes and would have had it relocated.
Wood does not need direct flame contact to pyrolyze. In this incident, heat from the steam pipe radiated to the wood joists and dried them out, which contributed to the ignition of the fire.
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The Tower Ladder 52 crew pulling the siding on the east side of the structure. Neighbors noticing the dark brown smoke coming from this area of the residence contacted the fire department. (Photos by Paul DiRienzo.)
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(1) The boiler exhaust system leads to the chimney. (2) Note the close proximity of the steam pipes to the electrical junction box. (3) The steam pipe penetrating the floor joist. (4) The flooring above the area of fire origin. (5) The area of fire origin.
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Very little of the contents was damaged by fire. The damage was inside the walls and ceilings.
RONALD J. RAKOSNIK is a 14-year veteran of the Lombard (IL) Fire Department, where he serves as a lieutenant on a 24-hour shift and has been involved in the Fire Investigation Unit for 13 years. He has an associate`s degree in fire science and is a certified Fire Officer II and Fire Investigator. He attended the University of Illinois Fire Service Institute at Champaign; the National Fire Academy in Emmitsburg, Maryland; the Chicago Fire Academy; and the Alcohol, Tobacco and Firearms Federal Law Enforcement Training Center in Glynnco, Georgia, as well as numerous seminars related to fire investigation. He has been a member of the International Association of Arson Investigators for 13 years.
