Does accidently connecting the wrong GPIO pins damage the Raspberry Pi or is there some protection like a fuse?
Connecting the power and ground pins simultaneously, or the correct combination of GPIO and power or ground pins can fry not only the pin but the entire PI (GPIO voltage levels are 3.3 V and are not 5 V tolerant. There is no over-voltage protection on the board) . You may want to check out this article from the elinux wiki regarding protecting the GPIO Pins
protected by goldilocks♦ Jul 2 '15 at 13:20
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