To create a mermaid diagram for the described single-phase 220V circuit, we can define the flow and connection of each component. Here's the structure for the diagram:

```mermaid
graph TD;
    A[Main Supply] --> B[Contactor]
    B --> C[Breaker]
    B --> G[Switch]
    C --> D1[PID Controller 1] & D2[PID Controller 2]
    D1 --> E1[SSR Relay 1]
    D2 --> E2[SSR Relay 2]
    E1 --> F1[Bandheater 1]
    E1 --> F2[Bandheater 2]
    E2 --> F3[Bandheater 3]
    E2 --> F4[Bandheater 4]
    E2 --> F5[Bandheater 5]
```

## Diagram Explanation

- **Main Supply** is the starting point of the circuit.
- The power goes into the **Contactor**, which is controlled by a **Switch**.
- From the Contactor, the power is routed to a **Breaker**.
- The Breaker outputs to two **PID Controllers** (1 and 2).
- Each PID Controller advances to its respective **SSR Relay** (1 and 2).
- SSR Relay 1 controls **Bandheaters 1** and **2**.
- SSR Relay 2 controls **Bandheaters 3**, **4**, and **5**. 

This structure illustrates a typical flow of power in a single-phase circuit with a focus on heating control.