Even after the energy source has been disconnected, in step 3  of the lockout safety process, and the machine has been locked out, in step 4, that doesn’t entirely guarantee that there’s no hazardous energy still stored within the machine or that it’s safe to perform maintenance.

At this time, it’s important to look for any hazardous energy that’s been “stored” within the machine, or any “residual” energy. During this phase, any potentially hazardous stored or residual energy must be releived, disconnected, restrained, or made non-hazardous in some other way.