Fire departments teach safety during hybrid car rescues

[Analog]

FORT WAYNE, Ind. - Some Indiana fire departments have begun training firefighters to minimize their chances of injury when rescuing people from hybrid cars.

Depending on the model, high-voltage lines in hybrid cars carry 144 volts to 650 volts _ a level that injure a person, State Farm Insurance spokesman Kip Diggs said.

Conventional vehicles use 12 volts for their electrical systems, he said.

"If you figure that's enough to move a car, it really hurts somebody," he said.

The voltage challenges firefighters who are trying to remove passengers pinned in their vehicles. Rescuers use various cutters and spreaders, some of which are hydraulic, to create enough space to remove passengers without harming them, they say.

High-voltage lines in hybrid cars are painted bright orange and are not running through parts usually found during extrications. But firefighters still need to know the potential danger of touching them, said Kirk Scott, an extrication instructor with the Fort Wayne Fire Department.

"The high voltage poses a real threat to us if not dealt with properly," he said.

Hybrid cars rely on electric motors for the most fuel-intensive aspects of acceleration, such as starting from a standstill. The vehicles revert to gasoline-fueled power when cruising. During cruising and braking, the gasoline engine charges the batteries to the electric motor, which saves on fuel consumption.

Besides a 12-volt battery for the electrical system like other cars, hybrid cars have a separate high-capacity battery pack to power the electric motor.

http://www.detnews.com/2005/autosinsider/0509/19/0auto-319444.htm

 

[geno]

I'm no electrician, but I thought that amperage is what kills people, not voltage?

 

[slpaulson]

Originally posted by: geno
I'm no electrician, but I thought that amperage is what kills people, not voltage?

Yeah, but unlike static there's a voltage source that can sustain a current.

I don't know if DC or AC is more dangerous than the other, but in these cars your playing with a higher voltage than you are with the electricity at the sockets in your house.

 

[Runes911]

Originally posted by: cRazYdood

Originally posted by: geno
I'm no electrician, but I thought that amperage is what kills people, not voltage?

Yeah, but unlike static there's a voltage source that can sustain a current.

I don't know if DC or AC is more dangerous than the other, but in these cars your playing with a higher voltage than you are with the electricity at the sockets in your house.

I believe DC is worse beacuse AC alternates and doesnt stay the same.

 

[Calin]

You can have all the amperage capacity you want, if the voltage is low enough, the amperage thru your body won't be dangerous. However, sweat (on hands) can dramatically reduce electrical resistence of the skin.
Have you touched the + point of the car battery while holding the ground of the car? You could try, there's no risk (unless you're sweaty on both hands). The amperage capacity of the automotive battery is in the neighbourhood of 100 amperes (or more).
Have you ever electrocuted yourself at a power socket? The amperage is limited to less than a quarter of the 100s of amperes. Which was more dangerous?

 

[DrPizza]

Also, AC has been shown to be more dangerous to humans than DC. At the same voltages and same currents, AC was more likely to cause death. As Calin pointed out, the most important factor is the resistance at the skin; the skin is a (relatively) good insulator. Once inside the body, your insides are a wonderful conductor of electricity.

 

[radioouman]

I agree that at full capacity, a couple hundred volts with significant current will injure someone. However, why would there be significant current flow when the vehicle has been in a crash? I believe that the most significant normal current flow would be when the electric motor is drawing maximum current, OR when there is a short. But the electric motor shouldn't be doing anything after the car has been in an accident.

 

[cjgallen]

LICK THE TERMINALS!

 

[geno]

Originally posted by: Calin
You can have all the amperage capacity you want, if the voltage is low enough, the amperage thru your body won't be dangerous. However, sweat (on hands) can dramatically reduce electrical resistence of the skin.
Have you touched the + point of the car battery while holding the ground of the car? You could try, there's no risk (unless you're sweaty on both hands). The amperage capacity of the automotive battery is in the neighbourhood of 100 amperes (or more).
Have you ever electrocuted yourself at a power socket? The amperage is limited to less than a quarter of the 100s of amperes. Which was more dangerous?

Like I said, I'm not candidate for graduating with an EE degree, but I always hear people say that amperage kills, that's all, just trying to figure out the logic is all...

 

[eelw]

Well at least this article is not stupid enough to say the 4 gauge battery wires are running along the doors.

 

[msparish]

Originally posted by: geno

Originally posted by: Calin
You can have all the amperage capacity you want, if the voltage is low enough, the amperage thru your body won't be dangerous. However, sweat (on hands) can dramatically reduce electrical resistence of the skin.
Have you touched the + point of the car battery while holding the ground of the car? You could try, there's no risk (unless you're sweaty on both hands). The amperage capacity of the automotive battery is in the neighbourhood of 100 amperes (or more).
Have you ever electrocuted yourself at a power socket? The amperage is limited to less than a quarter of the 100s of amperes. Which was more dangerous?

Like I said, I'm not candidate for graduating with an EE degree, but I always hear people say that amperage kills, that's all, just trying to figure out the logic is all...

Voltage is the driving force to get the amps to flow through you. On another note, AC and DC are both very dangerous. One benefit of AC that I have heard of however: if you grab an AC line, as the voltage changes, it can cause your hand to release it. Conversely, your hand will clench down on a DC line.