Abstract: A lead worker and his helper were installing a 4.5-metric-ton heating and cooling unit at a residence. The helper needed to crawl underneath the house to check the ductwork, so the lead directed him to get a light from the truck. While the lead worker continued hooking up the heating and cooling unit, the helper retrieved an extension cord set and a metal-cased portable handlamp rather than the flashlight from the truck. The helper went to the back of the house and plugged the extension cord set into an interior, grounding-type receptacle outlet. He ran the cord set outside through the sliding glass doors and connected the portable handlamp to the extension cord. The helper then crawled on his stomach under the house through the exterior crawl space. It had been steadily raining for a couple of days up to and including the day of the accident, and there was standing water around the exterior of the house and in the crawl space. Apparently, when the employee got about halfway under the house, the light bulb separated from its base, and the handlamp contacted some standing water, energizing the ground in the area where the helper was lying. The helper received an electric shock and lost consciousness. Because the lead worker did not hear any activity under the house, he called out to the helper. When the helper did not respond, the lead worker went around to the back of the house, where he saw the helper sticking halfway out of the crawl space. When the helper did not respond, the lead worker jerked the handlamp cord away from the injured employee. Emergency medical services were called to no avail. The helper had been electrocuted. (The employee did not test the outlet, but later testing by an electrician hired by the homeowner determined that the outlet did not have a ground.)