what is a switchboard
**A switchboard** (distribution panel/power distribution board) is a core device in the electrical power system used for **distributing,
controlling, and protecting electrical energy**. It is usually installed inside a building and is responsible for distributing the electrical
power from the main power source (such as the power grid or a generator) to various branch circuits. The following is a detailed
description of it:
I. Core Functions
1. **Power Distribution**:
Distribute the electrical energy from the main power source to multiple branch circuits (such as lighting, sockets, air conditioners, etc.).
2. **Circuit Protection**:
Protect the circuit from overload or short circuit through circuit breakers or fuses.
3. **Status Monitoring**:
Display the on-off status of each circuit, which is convenient for maintenance and management.
II. Main Components
| Component | Function |
| Main Circuit Breaker | Control the on-off of the entire switchboard, usually located at the top or center. |
| Branch Circuit Breaker | Each circuit corresponds to one circuit breaker, which will trip automatically to cut off the power in case of overload. |
| Busbar | Conductive copper busbars, connecting the main power source to each circuit breaker (live wire busbar), the neutral wire, and the ground wire (neutral wire/ground wire busbar). |
| Neutral Wire Busbar | Connect the neutral wires (white wires) of all circuits, usually with silver screw terminals. |
| Ground Wire Busbar | Connect the ground wires (yellow-green wires) of all circuits, usually with copper screw terminals. |
III. Common Types
1. **Main Switchboard**
- Directly connected to the incoming power line of the power grid, it is the main power hub of the building.
- It contains the main circuit breaker and all branch circuit breakers.
2. **Subpanel**
- Drawn from the main switchboard, it is used for power distribution at a long distance or in different zones
(such as garages, basements).
- It requires a separate configuration of circuit breakers and a ground wire busbar.
3. **Industrial Switchboard**
- Used in factories or large buildings, it supports three-phase electricity (208V/240V) and contains more
complex switching devices.
IV. Differences from Switch Box
| Comparison Items | Switchboard | Switch Box |
| Location | Usually in the basement, garage, or utility room | Inside the wall or ceiling, close to the lighting fixture/socket |
| Function | Overall power distribution and protection | Installation of single or multiple switches to control lighting fixtures/devices |
| Components | Circuit breakers, busbars, neutral wire/ground wire busbars | Switches, wire connectors, single/multiple cables |
| Voltage Level | 120V/240V (for household use) or higher (for industrial use) | 120V (for household switches) |
| Examples | Household distribution box (breaker box) | Light switch box and socket box on the wall |
V. Safety Precautions
1. **It is strictly prohibited to operate when the power is on**: Disconnect the main circuit breaker before operation and
confirm that there is no electricity with a voltage tester.
2. **Capacity Matching**:
- The capacity of the main switchboard needs to match the total load of the house (such as 100A, 200A).
- The current of the branch circuit breaker needs to match the wire specification (No. 14 wire is matched with 15A,
and No. 12 wire is matched with 20A).
3. **Grounding Requirements**:
- The ground wire of the main switchboard must be connected to the building grounding system (such as a grounding rod).
- The subpanel needs to be grounded separately and cannot share the ground wire with the neutral wire of the main
switchboard.
VI. Common Questions
- **Why does the switchboard have a burning smell?**
It may be due to poor contact of the circuit breaker or overload. The power should be cut off immediately for inspection
and repair.
- **Does the subpanel need a separate neutral wire busbar?**
Yes, the neutral wire and the ground wire of the subpanel must be separated and cannot be mixed.
**Conclusion**: The switchboard is the "heart" of the electrical power system, while the switch box is the "switch control
unit" at the end. The commonly seen "breaker box" in households is a type of main switchboard.
