Continuing the discussion from Current Device Deals & Best Prices:
They are both wires, but they serve very different purposes in a residential home circuit. One is grounded and one is grounding.
If most of your experience has been with battery operated devices, or in a physics lab, you are generally working with direct-current, and,the ground and the neutral may well work in a very similar way. In these environments you do sometimes hear the statement that the ground and neutral are interchangeable.
However, in a house, the ground will often be connected to a metal appliance such as a washing machine or a toaster, and normally carries very little current. Its purpose is to be used when there is a fault in the normal live circuit so that the extra current has someplace to go.
The neutral will be the return half of the live AC circuit.
So even though they are both wires, they typically function very differently.
Rerouting the ground into the live circuit runs the risk of both removing the grounding function and possibly pumping live current to that metal appliance. All depending on the exact wiring in that specific home, of course.
See the following:
In the US, electrical code requires following manufacturer instructions. If the manufacturer instructions call for four wires, then trying to get by with three is an intentional code violation. Not something to be undertaken lightly.
If the manufacturer instructions say that a neutral should be connected to a specific switch input, connecting a ground there again is an intentional code violation.
For more information on wiring network switches, see the wiring FAQ:
It can help to remember that our goal is not to power on a single individual switch, but rather to power on the switch while also maintaining the fire safety and electrical safety integrity of the whole house wiring system.
Submitted with respect.