1
00:00:00,560 --> 00:00:03,640
Speaker 1: Welcome to brain Stuff from house stuff works dot com,

2
00:00:03,640 --> 00:00:07,680
Speaker 1: where smart happens brought to you by Visa. We all

3
00:00:07,720 --> 00:00:10,560
Speaker 1: have things we like to think about. Online fraud shouldn't

4
00:00:10,600 --> 00:00:14,640
Speaker 1: be one of them, because with every purchase, Visa prevents, detects,

5
00:00:14,800 --> 00:00:22,840
Speaker 1: and resolves online fraud safe secure Visa. Hi, I'm Marshall

6
00:00:22,880 --> 00:00:26,040
Speaker 1: Brain with today's question. Why do the plugs on some

7
00:00:26,160 --> 00:00:30,560
Speaker 1: appliances have two prongs and others have three prongs. Let's

8
00:00:30,600 --> 00:00:33,360
Speaker 1: start with what the holes in an outlet do. When

9
00:00:33,360 --> 00:00:35,839
Speaker 1: you look at a normal hundred twenty volt outlet in

10
00:00:35,840 --> 00:00:39,120
Speaker 1: the United States, there are two vertical slots and then

11
00:00:39,120 --> 00:00:42,360
Speaker 1: a round hole centered below them. The left slot is

12
00:00:42,400 --> 00:00:46,080
Speaker 1: slightly larger than the right. The left slot is called neutral,

13
00:00:46,479 --> 00:00:49,320
Speaker 1: the right slot is called hot, and the whole below

14
00:00:49,360 --> 00:00:52,479
Speaker 1: them is called ground. The prongs on the plug fit

15
00:00:52,560 --> 00:00:55,800
Speaker 1: into these slots in the outlet. In a house outlet,

16
00:00:55,960 --> 00:00:58,960
Speaker 1: power flows from hot to neutral. Let's say you plug

17
00:00:59,040 --> 00:01:01,560
Speaker 1: a light bulb into the let. The power will flow

18
00:01:01,600 --> 00:01:04,319
Speaker 1: from the hot prong through the filament and back to

19
00:01:04,360 --> 00:01:08,600
Speaker 1: the neutral prong, creating light in the process. The groundhole

20
00:01:08,720 --> 00:01:11,720
Speaker 1: and the neutral slot of an outlet are identical. That is,

21
00:01:11,760 --> 00:01:14,000
Speaker 1: if you go back to the fuse box, you'll find

22
00:01:14,040 --> 00:01:16,800
Speaker 1: that the neutral and ground wires from all the outlets

23
00:01:16,840 --> 00:01:19,760
Speaker 1: go to the same place. They all connect to ground.

24
00:01:20,240 --> 00:01:22,760
Speaker 1: Since they both go to the same place, why do

25
00:01:22,800 --> 00:01:25,240
Speaker 1: you need both. If you look around your house, what

26
00:01:25,360 --> 00:01:28,039
Speaker 1: you'll find is that just about every appliance with a

27
00:01:28,120 --> 00:01:32,000
Speaker 1: metal case has a three pronged plug. This may also

28
00:01:32,040 --> 00:01:35,520
Speaker 1: include some things like your computer, that have a metal

29
00:01:35,520 --> 00:01:39,240
Speaker 1: in case power supply inside, even if the device itself

30
00:01:39,360 --> 00:01:43,039
Speaker 1: comes in a plastic case. The idea behind grounding is

31
00:01:43,120 --> 00:01:47,000
Speaker 1: to protect the people who use metal and cased appliances

32
00:01:47,120 --> 00:01:50,840
Speaker 1: from electric shock. The casing is connected directly to the

33
00:01:50,880 --> 00:01:54,560
Speaker 1: ground prong. Let's say that a wire comes loose inside

34
00:01:54,640 --> 00:01:58,320
Speaker 1: an ungrounded metal case and the loose wire touches the

35
00:01:58,360 --> 00:02:01,600
Speaker 1: metal case. If the loose wire is hot, then the

36
00:02:01,720 --> 00:02:05,080
Speaker 1: metal case is now hot and anyone who touches the

37
00:02:05,120 --> 00:02:08,240
Speaker 1: metal case will get a potentially fatal shock. With the

38
00:02:08,360 --> 00:02:12,520
Speaker 1: case grounded, the electricity from the hot wire flows straight

39
00:02:12,560 --> 00:02:15,680
Speaker 1: to ground, and this trips the fuse in the fuse box.

40
00:02:16,040 --> 00:02:18,880
Speaker 1: Now the appliance won't work, but it won't kill you either.

41
00:02:19,520 --> 00:02:22,440
Speaker 1: What happens if you cut off the ground prong or

42
00:02:22,639 --> 00:02:25,000
Speaker 1: you use a cheater plug so you can plug a

43
00:02:25,160 --> 00:02:29,400
Speaker 1: three pronged appliance into a two pronged outlet. Nothing really happens.

44
00:02:29,440 --> 00:02:33,160
Speaker 1: The appliance will still operate. What you've done, however, is

45
00:02:33,240 --> 00:02:36,800
Speaker 1: you've disabled an important safety feature that protects you from

46
00:02:36,840 --> 00:02:40,560
Speaker 1: an electric shock if a wire comes loose. Do you

47
00:02:40,600 --> 00:02:44,000
Speaker 1: have any ideas or suggestions for this podcast? If so,

48
00:02:44,120 --> 00:02:46,800
Speaker 1: please send me an email at podcast at how stuff

49
00:02:46,840 --> 00:02:49,600
Speaker 1: works dot com. For more on this and thousands of

50
00:02:49,600 --> 00:02:54,120
Speaker 1: other topics, go to how stuff works dot com