A vacuum interrupter may not be called upon to function to interrupt fault current for relatively lengthy periods of time. In the stand-by mode and carrying rated continuous current, some parts of the interrupter may reach temperatures substantially above ambient. Alternately, the interrupter may be stored for long periods before being placed into service. These two factors together constitute what is sometimes referred to as the shelf life, and they play an important role in determining the useful life of a vacuum interrupter. This paper describes and details an experimental approach to better determine shelf life of vacuum interrupters.