I’m trying to understand the reasoning behind grounding the negative side of a battery in vehicle electrical systems, given that the negative terminal has an abundance of electrons. In electron flow theory, electrons move from the negative terminal (where there is an excess of electrons) to the positive terminal (where there is a deficit of electrons).
If the negative terminal is the source of electrons, why do we consider it a “sink” and connect it to the chassis ground? Wouldn’t it make more sense to ground the positive side, which is where the electrons are flowing to?
Additionally, I’m interested in learning about the thought process and design principles that electrical engineers follow when making this decision. What are the safety, performance, and practical implications of grounding one terminal over the other?
In: Physics
BSEE here. Its arbitrary, but we needed a consistent ground across all circuits, so it was decided to make grounding the negative side be the standard. It could have been the positive side, it just has to be one side.
Now, there are some strange applications where an entire circuit is not grounded to ground, but grounded to a DC voltage above ground so the entire circuit has a ‘ground’ of 12V and a high of 24V. I remember a number of techs not paying attention to the warnings on the box and would sometimes ground the 12V side to 0V ground and melt the shielding of the ground wire and blow the fuse for it.
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