According to 200.3, premises wiring shall not be electrically connected to a supply system unless the supply system contains a corresponding grounded conductor. Which of the following is an exception to this requirement?

• When the premises wiring is for temporary installations less than 90 days.
• When the premises wiring is part of an isolated power system in a healthcare facility.
• When using listed utility-interactive inverters for PV or fuel cell systems, if the connected wiring or utility has a grounded conductor.
• When the supply system operates at less than 50 volts to ground.