residential electric meter box wiring diagram
The following is an illustration of the wiring diagram and an operation guide for a residential electric meter box, applicable to
single-phase (220V) and three-phase (380V) systems:
I. Core Components of the Electric Meter Box
1. **Electric Meter**: Measures the total electricity consumption and includes an **incoming line terminal (Line)** and an **outgoing
line terminal (Load)**.
2. **Main Circuit Breaker**: Controls the total power supply and trips in case of overload or short - circuit.
3. **Neutral Bar**: Connects all neutral wires (N).
4. **Ground Bar**: Connects the ground wire (PE) and needs to be connected to a grounding rod.
5. **Branch Circuit Breakers**: Manage different circuits (such as lighting, sockets, and air conditioners).
II. Wiring Diagram for Single - Phase Electric Meter Box (220V)
Wiring Steps:
1. **Incoming Line Connection (Power Supply Side)**:
- **Live Wire (Line Hot)**: A black/red wire connected to the **L1 incoming line terminal** of the electric meter.
- **Neutral Wire (Line Neutral)**: A white/blue wire connected to the **N incoming line terminal** of the electric meter.
- **Ground Wire (Ground)**: A green - yellow双色 wire connected to the **grounding terminal** of the electric meter or the
ground bar.
2. **Outgoing Line Connection (Load Side)**:
- **Live Wire (Load Hot)**: Connected from the **L1 outgoing line terminal** of the electric meter to the **incoming line terminal**
of the main circuit breaker.
- **Neutral Wire (Load Neutral)**: Connected from the **N outgoing line terminal** of the electric meter to the neutral bar.
- **Branch Wiring**:
- The live wire of each branch is connected from the **outgoing line terminal** of the main circuit breaker to the **incoming line
terminal** of the corresponding branch circuit breaker.
- The neutral wire of each branch is directly connected to the neutral bar.
- All ground wires are connected to the ground bar.
III. Wiring Diagram for Three - Phase Electric Meter Box (380V)
Wiring Steps:
1. **Incoming Line Connection (Power Supply Side)**:
- **Three - Phase Live Wires (L1/L2/L3)**: Yellow, green, and red wires respectively connected to the **L1/L2/L3 incoming line terminals
** of the electric meter.
- **Neutral Wire (N)**: A blue wire connected to the **N incoming line terminal** of the electric meter.
- **Ground Wire (PE)**: A green - yellow双色 wire connected to the grounding terminal.
2. **Outgoing Line Connection (Load Side)**:
- **Three - Phase Live Wires**: Connected from the **L1/L2/L3 outgoing line terminals** of the electric meter to the **incoming line
terminal** of the main circuit breaker.
- **Neutral Wire**: Connected to the neutral bar.
- **Branch Wiring**:
- For single - phase loads (such as sockets): One live wire, one neutral wire, and one ground wire. The live wire is connected to the
corresponding phase circuit breaker.
- For three - phase loads (such as air conditioners): Three live wires and one ground wire, without connecting the neutral wire.
IV. Key Precautions
1. **Power - Off Operation**:
- First, disconnect the total incoming power supply and confirm that there is no electricity with a voltmeter before wiring.
2. **Wire Specifications**:
- Incoming wires: Use **6 - 10mm²** copper wires for single - phase and **10 - 16mm²** copper wires for three - phase.
- Branch wires: Use **2.5mm²** for lighting and **4mm²** for sockets/air conditioners.
3. **Polarity and Identification**:
- Strictly distinguish between the live wire (L), neutral wire (N), and ground wire (PE), and do not mix them up.
- The neutral bar and the ground bar need to be insulated and cannot be directly connected.
4. **Circuit Breaker Matching**:
- The capacity of the main circuit breaker = the total household load current × 1.2 times (e.g., 80A).
- Branch circuit breakers: 16A for lighting, 20A for sockets, and 32A for air conditioners.
V. Diagram Reference
Schematic Diagram of Single - Phase Electric Meter Box Wiring:
Power Incoming Line ──┬── Electric Meter (L1 Incoming Line) ─── Main Circuit Breaker ── Branch Circuit Breaker ── Load
└── Electric Meter (N Incoming Line) ─── Neutral Bar ── Branch Neutral Wires
↓
Ground Bar (Grounding Rod)
Schematic Diagram of Three - Phase Electric Meter Box Wiring:
Three - Phase Power Supply ──┬── Electric Meter (L1/L2/L3 Incoming Lines) ─── Main Circuit Breaker ── Branch Circuit Breaker ── Load
└── Electric Meter (N Incoming Line) ─── Neutral Bar
↓
Ground Bar (Grounding Rod)
VI. Safety Regulations
1. The electric meter box needs to comply with the **UL 67** (USA) or **GB 7251** (China) standards.
2. Outdoor boxes need to reach the **IP54/IP65** protection level, and indoor boxes need to be well - ventilated and moisture - proof.
3. It is prohibited to privately disassemble the electric meter sealed by the power company. Wiring must be done by a licensed electrician
(required by regulations in some areas).
If you need more detailed diagrams, it is recommended to refer to the **installation manual of the electric meter box** provided by the
local power company or contact a professional electrician for on - site guidance.
