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.
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>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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Everything I’ve read has said to do black first for the reasons you have mentioned. (Edit to add: even manufacturers have black-then-red instructions on some of the packaging I’ve seen.) And I do it that way for those same reasons.
Don’t worry about the advice of ChatGPT just yet — it would be like asking a Reddit automod for dating advice at this point.
It doesnt really matter. It is supposed to prevent you from accidentally making short circuit by mixing wires. If you are not dumb and are using decently thick wires, it doesnt matter what cable you connect first or if you connect – to battery or car
edit: theoretically it can reduce sparking, but again.. doesnt make a difference
The reason you should connect the red cable before the black cable is that completing the circuit has a chance of creating a spark when the last connection is closed. A spark is better if it is somewhere away from the battery, which is why it is often suggested that the final connection is a black terminal to an unpainted part of the frame of the car with a dead battery. This part of the frame should be connected to ground and function just like if it was connected directly to the black terminal of the dead battery.
Why is the spark so bad? It is because a lead-acid battery (the kind in cars) generate hydrogen gas when recharged. It isn’t very much and usually won’t be a problem, but trying to keep sparks away from the battery helps to minimize the risk of an explosion.
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As for ChatGPT I think you are misunderstanding what it is. The program is a way of creating text that sounds like it comes from a person, basically like a massively complex version of the text prediction on your phone. It doesn’t know what it is saying, it doesn’t think or do reasoning, and because of this it is not a reliable source of knowledge.
It is easy to connect to the ground (black wire) in any location of a car engine, the metal part of the engine and the car body are directly connected to the ground. A good and simple connection for positive voltage (red wire) is often only available at the battery.
Batteries can give off hydrogen fumes so you do not what a spark there, which means it is simple to connect the black wire last in another location
You also what to avoid a direct short when you connect the wire that is a lot worse than some sparks when you connect it correctly, you can melt the wires and do a lot more damage. https://www.youtube.com/watch?v=ZfFViY1-zYw If you have connected the two cars with the black wire then all exposed metal parts are connected to the black wire.
When you connect the red wire to the battery of one car any mistake on the other car like connecting it to the wrong location or even just dropping it can result in short of the other battery of the first car. That is a very bad idea.
If you on the other and connect red first then the black wire can be connected to practically any other part except where the red wire is connected. Dropping the black wire will not result in a short. If you drop or connect the red wire incorrectly nothing will happen if you notice the mistake before the black wire is connected.
So red wire first reduces the risk of sparking in the wrong location and reduces the risk of you shorting the battery by mistake.
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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