Accident Report Detail

Accident Summary Nr: 200780153 - ELECTRIC SHOCK - GROUND FAULT IN FURNACE

Accident Summary Nr: 200780153 -- Report ID: 0626300 -- Event Date: 07/30/1997
Inspection Nr	Date Opened	SIC	NAICS	Establishment Name
300553161	08/01/1997	1711	0	Quigley Heating And A/C

Abstract: A heating and air conditioning contractor was hired to install a combustion air duct in a residential heating system. The 203-millimeter-diameter duct was to be installed about 760 millimeters above the floor in a closet enclosing the heating system. An employee assembled the duct in the attic, dropped it into the closet, and suspended it from a rafter with corrugated iron. He went to the closet and noticed that the area in which he had to work was very tight. He removed a gas line and squeezed into the closet to place additional screws in the duct. A metal box housing the fused, single-pole disconnect switch for the furnace was located on a wall adjacent to the furnace. To approach the duct, the employee had to place his back against the box. The circuit conductors supplying the disconnect box were run as metal-clad cable. The disconnect box supplied power to the furnace through a three-conductor jacketed cable containing three No. 16 AWG stranded copper conductors. All three conductors were exposed for a length of about 13 millimeters midway inside the furnace. One of the conductors was touching the metal frame of the furnace. The copper wire had signs of oxidation, indicating that this was an old break or a failure in the cord's insulation. No strain relief or bushing was present on the jacketed cord where it entered the furnace. The employee had his back against the metal disconnect box, and the cable to the furnace was across his shoulder. The homeowner's mother heard a grunt and rushed to the employee. When she tried to pull him out of the closet, she felt an electric shock, so she summoned emergency medical assistance to rescue the employee. Unfortunately, the rescue efforts were to no avail. The employee had been electrocuted. He had burn marks on his back. After the accident, signs of arcing were noted where the armor-clad cable was attached to the metal disconnect box. An examination of the wiring discovered that 40 volts, ac, were present on the conductors touching the furnace frame. When the conductor was moved away from the frame, the voltage rose to 120 volts.

Keywords: ENCLOSED SPACE, FURNACE, ELECTRICAL, ELECTRIC CABLE, E GI VII, ELECTROCUTED, GROUND FAULT, EQUIPMENT GROUNDING, ELECTRICAL BOX

Accident Details
End Use		Project Type		Project Cost	Stories	Non-building Height	Fatality
Commercial building		New project or new addition		$1,000,000 to $5,000,000	4	20	X

Employee Details
Employee #	Inspection Nr	Age	Sex	Degree of Injury	Nature of Injury	Occupation	Construction
1	300553161			Fatality	Electric Shock	Heating, air conditioning, and refrig. mechanics	Distance of Fall: feet Worker Height Above Ground/Floor: feet Cause: Interior plumbing, ducting, electrical work Fatality Cause: Electrocution by touching exposed wire/source

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