Patent ID: 6979233

Claim:
A method comprising: marking a first portion of a first connector used to supply a first type of electricity, by blocking one of the pins of the first connector, marking a corresponding location of a second connector which mates with the first connector, but is used with a second type of electricity, which is incompatable with said first type of electricity, by forming a protruding portion in a corresponding area to the blocked location, thereby preventing the second connector used for the second type of electricity from being inserted into the first connector used for the first type of electricity, wherein each of the first and second connectors have a plurality of pins, and where the first connector is a female connector and the second connector is a male connector, wherein each of the first and second connectors have a spare pin which is not used for electrical connection, and said first portion of the first connector and said corresponding portion of the second connector use an area of said spare pin, and wherein the connector is substantially round, and the spare pin is in the center.