What the heck does that third prong on a Western Hemisphere power plug do (the “ground”) if it isn’t necessary for all electronics?

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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

11 Answers

Anonymous 0 Comments

Double insulated is the answer, if it’s not double insulated the exposed metal parts of the appliance need to earthed, the earth/ground prong should never be cut off if it’s there it needs to be there

Anonymous 0 Comments

Some items have their own protections built in that keep you safe when things go wrong. Those don’t require a grounding wire. Other items are not made with protections so the grounding wire fills that role … to protest people, pets, and property. Removing the prong is a frankly asinine idea that may not kill you or me, or even anyone you will ever meet, but it does kill plenty of people every year.

Anonymous 0 Comments

It’s a safety feature on electronics that have a metal exterior, to prevent people from getting shocked, in case the wiring inside gets messed up and touches the case. It grounds the actual metal exterior. I guess it’s only necessary if you value your safety, LOL.

How and why it works is actually really interesting!

https://electronics.howstuffworks.com/everyday-tech/question110.htm

Anonymous 0 Comments

The 3 Prongs correspond to 3 different wires in the plug. The main one is the Live wire, in which the current flows through to go to the appliance. The second is a neutral wire which has no charge/current compared to the Live one. And finally the top prong is the earth wire which also has no charge, but is a form of prevention in the case of a surge of current through the plug and touches the metal casing, this allows for the current to be ‘earthed’ instantly reducing the current flowing.

Anonymous 0 Comments

It’s a grounding wire to protect users and electronics from power surges. You’re right it’s 100% not a necessity, but the more power something uses the more I would recommend using it. It’s essentially a safety feature. I don’t know if you know anything about jumping a car, but one of the cables you attach to metal under the hood instead of the negative of the car you’re jumping, it’s the same concept as that. You’re grounding it so if too much power goes through it will have somewhere to go.

Anonymous 0 Comments

The ground allows metal cases to discharge power if a short causes the case to become live. This will prevent your body from becoming the ground if you touch the metal case.

Anonymous 0 Comments

Three wire configuration: 1 the “hot” wire, 2 the neutral wire, and 3 the ground wire.

In normal operation, the hot wire brings power to the device and the neutral wire is the return path to the fuse/breaker box in your house.

The ground wire is a second return path for safety reasons.

Both the neutral wire and the ground wire are connected to the same ground bar inside your fuse/breaker box.

So if there’s a short in your device so that the path to ground via the neutral wire is broken, the ground wire provides an alternate path. Otherwise when you touch your device, YOU would be the alternate path to ground.

Anonymous 0 Comments

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.

Anonymous 0 Comments

It’s a safety feature that appliance manufacturers starting using in the 70’s.

Let’s say you drop a toaster with a metal exterior and it gets dented. Unbeknownst to you, the location of the dent on the toaster is directly over an exposed wire in the toasters circuitry. The inside dent of the metal toaster is now touching the exposed wire where the dent is. When you plug in the toaster and move it, the electrical current will is not going to toast your bread, instead it is going to travel through YOU. However, if the manufacturer had the foresight to install a wire connecting the inside of the metal frame to the ground (the third prong), the current will instead travel through the ground wire and trip a breaker instead of shocking you.

The toaster example isn’t something that would be likely to happen today as 99.9% of toasters made today have plastic exteriors (for your safety). But any appliance you see with a third prong has it as a safety measure in the circumstance that the circuitry should fault in an exposed part of the appliance.

Anonymous 0 Comments

For a practical example: PCs / NUCs that have only 2 prongs and are connected to the power outlet will sometimes give you a static shock when you touch them. Those with 3 prongs do not because they are constantly grounded.