Science · 6 pages · 12 min
Why a three-prong plug has a ground pin
The third pin bonds the metal case to ground so a fault can trip the breaker.
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From the opening
A three-prong plug has a ground pin so the exposed metal of an appliance is bonded to the building ground. If a live wire touches that metal, fault current has a route that is not a person, and the fuse or breaker can open. The opening covers how hot and neutral differ from ground, what a fault on the case does, and why the pin can seem idle.
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Inside
- How hot and neutral differ from ground
- What a fault on the case does
- Why the pin can seem idle
- How this differs from a ground-fault device
- Where the idea stops applying
- A distinction worth keeping
Sources
- The equipment grounding conductor bonded to exposed metal
- Fault current on that conductor opening the overcurrent device