Common mode failure has a more specific meaning in engineering. It refers to events which are not statistically independent. Failures in multiple parts of a system may be caused by a single fault, particularly random failures due to environmental conditions or aging. An example is when all of the pumps for a fire sprinkler system are located in one room. If the room becomes too hot for the pumps to operate, they will all fail at essentially the same time, from one cause (the heat in the room). Another example is an electronic system wherein a fault in a power supply injects noise onto a supply line, causing failures in multiple subsystems.