* Is inconveniently located (like in a hard-to-reach place).
* Is poorly labeled or unmarked, making it difficult to identify.
* Is prone to malfunction (like being sticky or unreliable).
The term originated from the Murphy's Law adage: "Anything that can go wrong will go wrong." It's used humorously to highlight the frustration of dealing with such switches.
There's no specific technical mechanism or design behind a "Murphy switch." It's simply a way of describing a frustrating and unreliable switch.
For example, a light switch located behind a heavy piece of furniture might be called a Murphy switch because it's difficult to access. Or, a switch that frequently flickers or fails to turn on could also be considered a Murphy switch.