Re: Why are prongs of electrical plugs different sizes (polarized)?

Date: Wed Sep 6 20:18:25 2000
Posted By: William Beaty, Electrical Engineer / Physics explainer / K-6 science textbook content provider
Area of science: Engineering
ID: 967875952.Eg

Message:

The basic reason is for lightning protection. One wire of every AC cord is connected to the earth. Lightning strikes then flow to the ground rather than leaping out of all the electric outlets. But grounding one side of the AC line causes problems. Human beings tend to stand upon the earth, which means that they are electrically in contact with one wire in every AC cord. The complete story is here:

WHY THREE PRONGS?
http://www.amasci.com/amat eur/whygnd.html

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