WEBVTT - Why do the plugs on some appliances have two prongs and others have three?

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<v Speaker 1>Welcome to brain Stuff from house stuff works dot com,

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<v Speaker 1>where smart happens brought to you by Visa. We all

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<v Speaker 1>Brain with today's question. Why do the plugs on some

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<v Speaker 1>appliances have two prongs and others have three prongs. Let's

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<v Speaker 1>start with what the holes in an outlet do. When

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<v Speaker 1>you look at a normal hundred twenty volt outlet in

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<v Speaker 1>the United States, there are two vertical slots and then

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<v Speaker 1>a round hole centered below them. The left slot is

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<v Speaker 1>slightly larger than the right. The left slot is called neutral,

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<v Speaker 1>the right slot is called hot, and the whole below

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<v Speaker 1>them is called ground. The prongs on the plug fit

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<v Speaker 1>into these slots in the outlet. In a house outlet,

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<v Speaker 1>power flows from hot to neutral. Let's say you plug

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<v Speaker 1>a light bulb into the let. The power will flow

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<v Speaker 1>from the hot prong through the filament and back to

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<v Speaker 1>the neutral prong, creating light in the process. The groundhole

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<v Speaker 1>and the neutral slot of an outlet are identical. That is,

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<v Speaker 1>if you go back to the fuse box, you'll find

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<v Speaker 1>that the neutral and ground wires from all the outlets

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<v Speaker 1>go to the same place. They all connect to ground.

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<v Speaker 1>Since they both go to the same place, why do

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<v Speaker 1>you need both. If you look around your house, what

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<v Speaker 1>you'll find is that just about every appliance with a

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<v Speaker 1>metal case has a three pronged plug. This may also

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<v Speaker 1>include some things like your computer, that have a metal

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<v Speaker 1>in case power supply inside, even if the device itself

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<v Speaker 1>comes in a plastic case. The idea behind grounding is

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<v Speaker 1>to protect the people who use metal and cased appliances

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<v Speaker 1>from electric shock. The casing is connected directly to the

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<v Speaker 1>ground prong. Let's say that a wire comes loose inside

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<v Speaker 1>an ungrounded metal case and the loose wire touches the

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<v Speaker 1>metal case. If the loose wire is hot, then the

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<v Speaker 1>metal case is now hot and anyone who touches the

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<v Speaker 1>metal case will get a potentially fatal shock. With the

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<v Speaker 1>case grounded, the electricity from the hot wire flows straight

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<v Speaker 1>to ground, and this trips the fuse in the fuse box.

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<v Speaker 1>Now the appliance won't work, but it won't kill you either.

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<v Speaker 1>What happens if you cut off the ground prong or

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<v Speaker 1>you use a cheater plug so you can plug a

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<v Speaker 1>three pronged appliance into a two pronged outlet. Nothing really happens.

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<v Speaker 1>The appliance will still operate. What you've done, however, is

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<v Speaker 1>you've disabled an important safety feature that protects you from

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<v Speaker 1>an electric shock if a wire comes loose. Do you

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<v Speaker 1>have any ideas or suggestions for this podcast? If so,

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<v Speaker 1>please send me an email at podcast at how stuff

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<v Speaker 1>works dot com. For more on this and thousands of

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<v Speaker 1>other topics, go to how stuff works dot com