An apparatus includes an enclosure, a power switch, an absence of voltage detector controller, and an absence of voltage detector. The power switch is mounted inside the enclosure and configured to switch electrical power from a line-side power line to a load-side power line. The load-side power line is configured to transfer the electrical power outside of the enclosure to an industrial control panel. The absence of voltage detector controller is configured to determine a presence and an absence of each of a plurality of phases of the electric power on the load-side power line inside the enclosure. The absence of voltage detector is visible from external to the enclosure, has a switch, and is configured to illuminate one or more lamps indicating the absence of the electrical power on a corresponding one or more of the plurality of phases in response to a pressing of the switch.