why are there separate neutral and ground wires for electricity when they both are connected to the same thing.
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Electricity runs in a circuit like cars on a race track. Each car wants to return back to the starting/finish line as quickly as possible. Electricity wants to return back to its source with the least effort possible. So what we can do is provide it a low resistance way of doing so. In AC systems, energy comes from the hot wire, gets used up to your device, then flows back to its source (usually a local transformer) at little or no voltage. Another way to envision this is washing your car with a power washer. Water comes out at high pressure, gets used up to clean your car, then slowly rolls down the driveway to the sewer once it’s used up, where it returns to the treatment plant. In this case, the driveway is your neutral.
Ground and neutral are often the same thing. If you were to open your breaker box (not advised!), you’d see they’re usually connected together. The ground wire though is a safety measure that provides a low resistance path for flowing current. You’ll notice, at least in North America, that not every electrical device has a ground. Some plugs just have the two prongs. Devices enclosed in non-conductive materials like plastic don’t need it. Metal appliances do, however. If a wire insider were to become loose or damaged, and touched the metal casing, you could get a nasty shock if you touched it. What the ground wire does is provide a lower resistance path for the electricity to return to its source than your body. The sudden current spike on the ground will usually trip the breaker, shutting off the power. Now, you could just use the neutral wire, but there might be cases were the hot and neutral somehow get reversed. Plus it adds some redundancy.
GFCI (RCDs in Europe) circuits are also used as a similar safety measure in addition to grounding, and also work with ungrounded appliances. What they do is measure current going into the device via the hot wire. versus what’s leaving via the neutral. If they detect any imbalance, the electronics inside cut the power virtually instantaneously. They’re usually mandatory in wet environments, since water (anything that’s not pure, which is most water) conducts electricity.
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