Learn why newer electric sockets have three holes instead of two.
In 1962, the third hole was added to electric sockets for grounding purposes. Previously, electrical plugs with two prongs could give the user a shock if a short circuit in the wiring or in the electrical device developed.
Since then ''double-insulated'' pronged plugs were developed (with fatter ends) that do not require a third prong for protection. But these new double-insulated prongs require new wide-slotted receptacles.