Before revision: The hazard was made worse because the on/off switch was often in the wire of the mains supply which was connected to the chassis, meaning that the chassis was "hot" when the on/off switch was 'on' or hot when that switch was 'off', depending on which way the plug was inserted in the power outlet.
After revision: The hazard could be made worse because the set was either often in the wire of the mains supply which was connected to the chassis, meaning that the chassis was "hot" when the on/off switch was 'on' or 'off', depending on which way the plug was inserted in the power outlet.