How to connect series cables in a distribution box

In a distribution box, cables are connected in a series-like arrangement where the main supply feeds the protective devices, and each subsequent device or load receives power from the previous one, often using pigtailing or direct series connections for continuity.

Main Supply to Protective Devices

The incoming phase and neutral wires from the main power supply are first connected to the input terminals of the main MCB (double-pole for single-phase systems) in the distribution box. The output of the main MCB then feeds the RCCB, which provides protection against leakage currents and electrical shocks. From the RCCB, the phase and neutral wires are routed to the branch MCBs that control individual loads or circuits ( ).

Series-Like Connections for Loads

Although household circuits are technically wired in parallel, the physical wiring often resembles a series or “daisy-chain” layout. For example, in LED installations, a two-core conductor can be inserted into the distribution box and connected by a simple press mechanism, allowing multiple LED spots to be powered sequentially from the same line ( ). In standard outlets, the pigtailing method is used: the incoming and outgoing wires are twisted together with a short pigtail wire, which connects to the device terminal. This ensures that if one device fails, the downstream devices still receive power ( ).

Neutral and Earth Connections

The neutral wires from all branch circuits are connected to a neutral link, while the earth wires are connected to an earth link. This provides a common return path and grounding for safety. The metallic body of the distribution box is also bonded to the earth link to prevent electric shock ( ).

Wiring Practices

• Phase wires are routed from the RCCB output to the input of each branch MCB.
• Double-pole MCBs for special loads carry both phase and neutral.
• Single-pole MCBs carry only the phase, with neutral connected to the neutral link.
• Wires are often bound with plastic ties for neatness and safety, and the wiring direction is typically left-to-right from main to branch circuits ( ). This configuration ensures that power flows sequentially through protective devices while maintaining safety and continuity for all connected loads.