This extra prong is a safety feature that redirects excess electricity safely into the ground. Knowing this distinction matters since using an adapter to plug a three-prong device into a two-prong ...

Since its invention back in 1904 by Harvey Hubbell the plug has not really undergone a change in form, its purpose was for lighting in the home. The 3 prong plug, invented by Phillip Labre in 1926 ...

A standard 3-prong outlet is the most common and cheapest ... is a big reason why modern homes exclusively use three-prong plugs. Although old two-prong wiring is often safe, the added safety ...