Final answer:
The green wire in a 4-way flat connector is generally connected to the earth/ground and is attached to the appliance's case to prevent electrical shock by ensuring the case is at zero volts.
Step-by-step explanation:
The green wire of a 4-way flat connector is typically used to connect to the earth/ground. In electrical systems, the earth/ground connection provides a low-resistance path directly to the earth. The green wire is connected to the case of the appliance to ensure it is at zero volts, making it safe and providing a path to complete the electrical circuit in the event of a fault.
When dealing with electrical wiring, it is essential to correctly identify the color-coding of wires. In most regions, the green wire, or sometimes a yellow wire with or without stripes, is designated for grounding purposes. However, always verify the color codes for your specific region as they can vary internationally.