# Ground is Any Metal Surface?

## Main Question or Discussion Point

Hey, I was looking at a car and the dealer told me the battery is at the back in the trunk. When he opened the hood he showed me how I would jump it if needed or anything else. He said there is one rod (that was visible coming through a connection from the battery) for the positive and for the ground I would just connect to any metal surface on the car.

Thinking about this can someone explain why the ground can be connected to any metal surface on the car??????

I know the ground is just a reference point but is the ground of the battery connected to the metal surface of the car too? How does this make sense..

Thanks!

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Astronuc
Staff Emeritus
Ground is the reference potential with respect to the rest of the circuitry connected to it, and normally, it would refer to the potential of the earth's surface.

On a car, the negative terminal of the battery is connected to the frame, and that is the reference potential for the electrical system in the car.

so by touching the battery's positive terminal and the metal surface can and individual get electrocuted?

turbo
Gold Member
so by touching the battery's positive terminal and the metal surface can and individual get electrocuted?
a potential of 12V isn't going to do much to you because your body is quite resistive. What the salesman apparently did not make clear enough is that when charging a battery or jumping a battery from another vehicle, the battery can be emitting hydrogen gas. Therefor it is safer to connect to the positive terminal first, then attach the other lead to a grounded metal part a bit distant from the battery. When the battery is charged up (or the vehicle is jump-started) the lead to ground should be removed first, and then the lead to the positive terminal. The ensures that if there is a spark upon connect/disconnect, the spark occurs some distance away from the battery.

so by touching the battery's positive terminal and the metal surface can and individual get electrocuted?
Current will flow through your body, but not enough to feel it.

Okay thank you to all replies