I’ve seen numerous videos on YouTube instructing to attach the red cable and then the black cable when jump starting a car (e.g. [1](https://www.youtube.com/watch?v=iI1o2hNy2hE), [2](https://www.youtube.com/watch?v=VdnkRQF5Cps), [3](https://www.youtube.com/watch?v=hyLwfthYjKw)).
However, to my understanding, black is for ground, and the reason for connecting ground in electrical systems is to prevent a potential voltage difference and creating a path for the excess current to flow into the ground (excuse me if I messed up “voltage” & “current”, my knowledge in that field is minimal). If that’s the case, then wouldn’t I want to ensure ground is connected first to prevent the risk of a voltage difference through the red cable?
I asked ChatGPT about the right order and it said “red then black”, then I explained my reasoning behind why I think black should go first, and then it said:
>You raise a good point. In some cases, it may actually be safer to connect the ground (black) cable first.
>
>To minimize the risk of sparking or arcing, it’s generally a good idea to connect the ground (black) cable to a metal part of the engine block before connecting the positive (red) cable. This will ensure that there is a low-resistance path to ground in case there is a potential difference between the batteries.
EDIT: Same question about the recommended reverse order of disconnecting. Why first disconnect black then red? Shouldn’t I make sure ground is connected at all times during a circuit? If I disconnect ground first, then red is connected on its own, raising the risk of an excess current.
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So my understanding is that the way automotive systems are wired, your red (positive) is the “live” side and the black (ground) is the neutral side. Your automotive frame and engine is also often a ground.
If you connect the black first, the frame/engine is in the circuit, so if there’s a short or bad wiring that could contact the frame, and you are touching the frame or engine – then when you connect the red lead you could create a ground to the earth, which you are a part of that circuit.
If the red lead is connected first, and there is a short or other issue, you will know right away (it will spark, or give you a small zap) before the connection is firmly clamped.
When the red lead is clamped, the black lead can be safely attached to the battery (or frame or engine for jumping), because that ground loop circuit will be the path of least resistance for any current, avoiding grounding through you to the earth or otherwise.
With modern automotive electrical harnesses, most of these scenarios are extremely rare due to the distribution through a fuse box which will prevent shorts from discharging significant amounts of power for long enough to be a health hazard.
But regardless, it’s still a good practice.
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