Sometimes NEUTRAL and GROUND wires connect to the same point eventually. GROUND is physically connected to the earth or the ground, hence the name GROUND. Real original isn't it? This is usually accomplished by a metal water pipe coming into the home. Since it goes thru the ground outside your home, it is said to be grounded. Sometimes a ground wire connects to a grounding rod which is usually an 8 foot long copper or copper clad steel rod that is pounded into the earth. A good GROUND is essential and is never to be used as neutral. A neutral wire is actually "hot" as it carries AC back to the panel from a live circuit. A ground wire is usually coated with a green conductor or sometimes is even a bare wire. GROUND is not intended to actually carry any type of AC load. It is a failsafe in case of a short inside the outlet or switch box that will short any stray AC back to the panel neutral in turn tripping the circuit breaker off thereby cutting the power to the circuit that has failed or shorted. If you didn't have a ground connected say to a switch wired in an electrical box, if for whatever reason AC came into contact with the box (if metal), the screws on the wall plate or if it's a metal wall plate would become "hot" and zap you when you touched it. The same would be true of any electrical appliance say for example a washing machine. If the AC shorted to the machines metal exterior, you would be zapped if their was no proper ground since the washer would be like one live wire and you would be pretty well grounded if standing barefoot on the basement floor. A properly wired ground would have tripped the circuit breaker without you having to find it out the hard way. A proper ground is also needed when using a GFCI outlet or breaker for them to function properly. So basically, do not ever use a ground wire as a neutral wire as you could be shocked, burn your house down, or be killed. It may seem silly to have a ground and neutral wire connected to the same point in the breaker box, but it is for safety so don't ignore them.

One more safety tip, shut off the main power when wiring anything to your circuit breaker box! Also, if wiring in a switch or outlet, shut off the power at the circuit breaker. You'd think this would be a given, but I've had some customers tell me they didn't shut off the power when wiring something in. Obviously since they were able to tell me this, they survived the attempt.