Electrician shocked by energized non-metallic sheathed emergency lighting cable

An emergency lighting system was undergoing some minor renovations when an electric shock incident occurred. The emergency lighting system consists of an emergency lighting pack and extra low voltage (12 volts DC) emergency lights located through the commercial building.

The emergency lighting pack is supplied by a separate circuit breaker powered through a multi-tap transformer that allows this style of emergency pack to be connected to a variety of input voltages. At this location the voltage is 120 volts AC. This equipment could also be connected to 277, or 347 volts AC. Whenever one voltage tap is used, the other tap wires on the same transformer winding become energized. The un-used tap wires are kept isolated, with their wire ends capped.