Hell, I’ve even seen people rip them off to fit 3 prong plugs into 2 prong extension cords. I’m sure it’s not safe, but I dont know why and why they would be necessary sometimes and sometimes not.
In: Engineering
So you have a drill you are using. The motor has two wires going to it: the hot and the neutral. They do the normal circuit for the drill. Now there are parts of that drill that are conductive and exposed to you, the human. To try and help you from being a dead human they ground the casing/metal of the tool.
That ground wire runs from the metal bits you can touch directly to the wall, through a dedicated wire to the ground bus and from there to ground. If the power wire gets shorted to he case/metal bit and there is no ground wire, YOU become the human ground wire. The current follows the least restrictive path to ground. In this case you. If it passes through you heart, well that could make you dead.
No on our three prong plug device that metal you are touching has that low resistance direct connection to ground. So that shorting current will go through the wire and not you! So you may get a small bit of current but much less likelihood of being killed. ie a little bzzt instead of CPR while we wait for the ambulance.
Now the two prong plug with the size difference. Nope not a birthmark of the appliance. With two wire systems one is the hot the other is the neutral. The hot wire always has voltage on it. If you measure that side of the outlet to ground it will be 120V. The neutral side will read 0 volts to ground.
now your standard plug with no size difference can go in either way. So let’s say you have a nice hair dryer. That hair dryer circuitry on the inside has a switch that is at one side of the electrical connections in the dryer. With same size plugs you plug in one way and all of the internal wiring and heating elements are at 120 volts since the switch is on the “backend” of the circuit. Plug it the other way around and the voltage is only up the switch. It’s at the front end of the circuit. That bigger prong only lets you plug it in so that the switch is front end and you only have voltage up to he switch connection.
It is also to limit the ability of the electricity to kill you or start fires.
So Safest is 3 prong. Second safest is two prong with off sized prongs. Lowest safety is the standard one size jams in however you want it to plug.
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