The standard for computer power cords is followed internationally.
There are 150 different AC adapter styles in North America alone; the variety exists to make it hard for users to become hurt or damage their electrical equipment by using the wrong power adapter. When looking for an AC adapter for your electrical device, look at the voltage, the current and the tip polarity.
Everyday Appliances
Your vacuum cleaner, lamps and personal electronics likely use the
NEMA 5-15P male plug which has two straight prongs --- one sometimes bigger than the other; sometimes there will be a third prong, known as the grounding prong. This cord supplies 120 volts and 15 amps.
Computers
The most common power cord for computers and servers, and most other standard business equipment, is IEC 60320 C13 / C14. This is the power cord that plugs into most desktop computers and monitors, with the C14 end being what goes in the outlet --- two flat prongs and a grounding prong --- while the other end (C13) looks like the inverse of this. This cord supplies 10 amps.
Large Household Appliances
Ovens, dryers, and other large household appliances have three or four pins; the appliances that use four prongs are equipped with a safety ground, while the ones that are exclusively three pronged are not. Most of these appliances already have the cords connected to the machinery and cannot not be accidentally plugged into the wrong kind of outlet.
Connectors
There are two major kinds of connectors: straight pronged and twist-lock, both of which are exactly what they sound like. Twist-lock plugs are not as common for NEMA 5-15P 15-amp connectors, though you're just as likely to see them as straight-prongs for other NEMA connections.
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