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Speaker 1: Welcome to brain Stuff from house stuff works dot com

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Speaker 1: where smart happens. Hi Am Marshall Brain with today's question,

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Speaker 1: why do the two flat prongs on plugs for most

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Speaker 1: electrical appliances have holes in them? If you unplug any

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Speaker 1: appliance in your house, there's a nine percent chance that

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Speaker 1: the two flat prongs have holes in them. There are

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Speaker 1: three reasons for those holes. First, if you were to

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Speaker 1: take a part in outlet and look at the contact

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Speaker 1: wipers that those prongs slide into, you would find that

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Speaker 1: they have bumps on them. These bumps fit into the

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Speaker 1: holes so that the outlet can grip the plugs prongs

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Speaker 1: more firmly. This detenting prevents the plug from slipping out

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Speaker 1: of the socket due to the weight of the plug

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Speaker 1: in the cord. It also improves the contact between the

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Speaker 1: plug and the outlet. Second, electrical devices can be factory

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Speaker 1: sealed or locked out by the manufacturer or owner using

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Speaker 1: a plastic tie or a small padlock that runs through

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Speaker 1: one or both of those prong holes. For example, a

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Speaker 1: manufacturer might apply a plastic band through the hole and

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Speaker 1: attach a tag to it that says you must do

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Speaker 1: blah blah blah before plugging in this device. The user

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Speaker 1: can't plug in the device without removing the tags, so

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Speaker 1: the user is sure to see the instructions. Third, there's

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Speaker 1: also a small savings and raw materials for the manufacturer

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Speaker 1: of the actual plug prong. Every little bit helps. It's

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Speaker 1: been reported that really old outlets used captive ball bearings

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Speaker 1: in coil springs for the detent, but today it's done

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Speaker 1: with a bump on a springy copper contact. Do you

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Speaker 1: have any ideas or suggestions for this podcast? If so,

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Speaker 1: please send me an email at podcast at how stuff

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Speaker 1: works dot com. For more on this and thousands of

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Speaker 1: other topics, go to how stuff works dot com and

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Speaker 1: be sure to check out the brain stuff blog on

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Speaker 1: the house stuff works dot com home page two