The Grounding Pin
We've seen that household appliances are in parallel, and that each prong of the plug is attached to one end of the power company's circuit.
The third pin actually doesn't go to the power company. It's wired to a pipe into the ground, symbolized by the triangle with progressively smaller lines just above the yellow whiteboard marker.
The purpose of the grounding pin is to protect against wiring faults. Nothing lasts forever (even cold November Rain) and occasionally, the connections between wires inside an appliance can work lose. This is very dangerous, if the wires make contact with the outside of the appliance. As shown in the bottom picture, the black wire has become unattached, meaning that current can't flow through the intended circuit. If you then touch the appliance, it will flow through YOU, as the voltage pushes current to the ground.
A much safer situation is the top drawing. Here, we've wired the appliance's casing to the ground. Thus the voltage pushes the current to the ground, and since this short circuit is probably very low resistance, a circuit breaker will blow. If you have an appliance that blows a circuit every time you plug it in, someone qualified needs to check it.
Grounding serves another purpose as well, it prevents static charges from building up on an object that they could damage, like a computer. Never defeat a grounding pin- it's there to protect you, and your property.
The Grounding Pin
We've seen that household appliances are in parallel, and that each prong of the plug is attached to one end of the power company's circuit.
The third pin actually doesn't go to the power company. It's wired to a pipe into the ground, symbolized by the triangle with progressively smaller lines just above the yellow whiteboard marker.
The purpose of the grounding pin is to protect against wiring faults. Nothing lasts forever (even cold November Rain) and occasionally, the connections between wires inside an appliance can work lose. This is very dangerous, if the wires make contact with the outside of the appliance. As shown in the bottom picture, the black wire has become unattached, meaning that current can't flow through the intended circuit. If you then touch the appliance, it will flow through YOU, as the voltage pushes current to the ground.
A much safer situation is the top drawing. Here, we've wired the appliance's casing to the ground. Thus the voltage pushes the current to the ground, and since this short circuit is probably very low resistance, a circuit breaker will blow. If you have an appliance that blows a circuit every time you plug it in, someone qualified needs to check it.
Grounding serves another purpose as well, it prevents static charges from building up on an object that they could damage, like a computer. Never defeat a grounding pin- it's there to protect you, and your property.