Firefighters Learn Hybrid Car Accident Scene Safety

Posted on: 26 January 2006

Before Ronald Hoffman, chief of the Linn Fire Protection District, and his colleagues took a University of Missouri Extension safety course on hybrid cars, he admits there was apprehension when working on such vehicles at a crash scene.

The firefighters feared electrocution. The hybrid cars, which run jointly from gasoline engines and battery power, have a 600-plus volt charge running through certain wires. Cutting one of those wires with a tool such as the jaws of life could kill a firefighter.

"I think there is a reluctance to work on a hybrid in an (victim) extraction scenario," Hoffman said, with "the rumors of what to touch and what not to touch."

For the most part, rescue workers shouldn't fear the new vehicles, said Alan Braun, an adjunct instructor with MU Extension's Fire and Rescue Training Institute. Braun also is part-owner of an auto repair shop and a volunteer firefighter and training officer with the Cole County Fire Protection District.

He teaches an MU FRTI course designed to help emergency responders deal with the potential hazards created by new car features. His curriculum includes hybrid car extraction safety and airbag safety.

Airbags can, in rare cases, deploy well after an accident potentially injuring both the crash victim and rescue worker.

"Every class I go to (firefighters) are scared to death of airbags and hybrids," Braun said. "You're scared of what you don't know."

His three-hour course is taught as a stand-alone class or is taught as a portion of a multi-day course on vehicle extraction with other FRTI rescue instructors.

"The manufacturers have installed several different ways to make hybrids safe," Braun said. "These vehicles have been built, in my opinion, very well."

Hybrid vehicles have relays that are designed to open during a crash and allow the car to de-energize. Some cars - the Toyota Prius is one - are being designed with a readily accessible fuse that emergency workers can pull to de-energize the car.

It takes roughly five minutes for a hybrid vehicle to de-energize.

Braun instructs emergency personnel to disconnect the 12-volt battery that supplies power to a vehicle's main computer. When the computer goes down the larger high-voltage batteries - the dual battery packs common in hybrids often total 600 to 650 volts - will shut down and the car will begin to de-energize.

Students are taught to remove the battery cable bolts, black first, red last. They then should either tuck the cables under the engine or tape them down safely away from the terminals. Braun does not recommend cutting the cables. He has seen rescue workers inexperienced in auto repair cut only some of the necessary cables.

Workers then should quickly inspect the car for other possible power sources. A cell phone plugged into a cigarette lighter can provide a charge back into the vehicle. He said young drivers sometimes power amplifiers and stereos with extra batteries, which also can leave a charge in the computer system.

After disconnecting all power supplies and waiting five minutes for the vehicle to de-energize, emergency personnel can use an extraction tool, being careful to avoid cutting areas where the orange-colored high-voltage wires run. The wires are located under the vehicle along the frame rail away from the exhaust system.

When extinguishing a hybrid vehicle fire, Braun said to avoid spraying water into the battery vents on the side of some vehicles. Water can cause a chemical reaction and the spewing of potentially toxic fumes.

Hoffman, the Linn fire chief, said firefighters have used what they learned from the MU course.

"We learned what to look for and how to disconnect batteries," Hoffman said. "It really put us at ease, informing us that it's not as dangerous as we had thought."

Braun said there is always some danger in emergency response work.

"You run into a burning building. Is this any worse?" Braun said of hybrid vehicles. "We're firefighters. We take risks. Dealing with this is not much different."

Braun said that to his knowledge passengers and drivers of hybrid cars are at little to no risk of electrocution based on their position in the vehicle, insulation and other safeguards designed into cars.