We all know that electrical wiring typically has three wires: live, neutral, and ground. These three wires also differ in color. Generally, they can be easily distinguished by color: the red wire represents the live wire, the blue wire represents the neutral wire, and the red-green wire represents the ground wire. But what are the specific differences between the ground and neutral wires? How can we more accurately distinguish them? The following article will explain these two points in detail.
Differences Between Ground and Neutral Wires
1. Different Concepts
The ground wire connects the outer casing of a device or electrical appliance to the ground to prevent electric shock accidents. The neutral wire is the connection between the three tail wires of the three-phase power supply and is also called the neutral wire. When the three phases are balanced, no current flows through the neutral wire. It is directly or indirectly connected to the ground, and its voltage relative to the ground is close to zero.
2. Different Functions
The neutral wire is primarily used in the working circuit. It connects to the live wire and carries current. The current flowing through the neutral wire for each phase is equal to the current flowing through the corresponding live wire. The ground wire, on the other hand, is primarily a protective wire and carries no current.
3. Different Wiring Locations
The neutral wire is the wire that extends from the transformer's neutral point, while the ground wire extends from the building's grounding system.
4. Different Practical Applications After Electric Shock
A good grounding system can effectively trigger the leakage current protector (RCD) to cut off power, protecting electrical appliances. The grounding wire is connected in parallel throughout the system and is not allowed to pass through a switch.
Each household can disconnect the neutral wire themselves; the two cannot be interchanged. If the ground wire is used as the working neutral wire and an excessive current flows, the grounding wire burns out. At this point, all appliance casings below the disconnection point will become live, posing a greater risk of electric shock.
How to Distinguish the Neutral and Ground Wires
1. Wiring Standards
The live wire (L) must be red, yellow, or green.
The neutral wire (N) must be black or blue.
The ground wire (PE) must be yellow or green.
Two-color wire facing a three-outlet socket
Left neutral, right live, center ground.
2. Install a residual current circuit breaker on the bus.
Connect a light bulb to the live and neutral wires or the live and ground wires. If the residual current circuit breaker activates, it indicates the ground wire; otherwise, it indicates the neutral wire.
Be careful when testing; there may be small sparks, so be prepared and don't get startled!
3. Test with a tester
① Turn on the power and test with a tester. All that lights up are the live wires.
② Disconnect the neutral wire at the main switch, leaving only the live wire connected. Turn on the lights in your home and test with a tester. If they were off just now, they are all the neutral wires.
③ All the remaining unlit wires are the ground wires.
The simplest method is to take a 220V lightbulb and use a test pen to determine the live wire. Then, connect two wires to the lamp holder, along with the live wire. You can tell the difference between neutral and ground by the brightness: the brighter one is the neutral wire, and the dimmer one is the ground wire.
4. Using a Multimeter
Set the multimeter to the 500V AC setting. Hold one test lead and touch the other to each power line. The higher voltage is the live wire, the lower voltage is the neutral wire, and the zero voltage is the ground wire.
A neutral wire with a resistance of less than 4 ohms to ground is a reliable ground.
Use the multimeter to the 250V AC setting to measure the voltage difference between the live and neutral wires, and between the live and ground wires. A difference of less than 5V indicates a reliable ground.
Many homeowners choose to do simple home wiring themselves, so understanding this knowledge is essential. One thing we should be aware of is that connecting the neutral and ground wires in reverse or mixed up is generally safe, but can be dangerous. The ground wire should never be connected to the neutral wire, as this can cause the device casing to become live. So I hope this article can be of some help to you when you don’t understand the circuit.
