Cables connected in the distribution box

In a distribution box, the main phase and neutral cables are first connected to the main isolator or double-pole MCB, then routed through protective devices like RCCBs and single-pole MCBs, with neutral and earth lines connected to their respective busbars before distributing power to subcircuits.Main Supply ConnectionThe incoming phase (live) and neutral cables from the utility or energy meter are first connected to the main isolator or double-pole MCB, which acts as the main switch for the entire electrical system. This device allows manual disconnection of power for safety and maintenance purposes .Protective DevicesFrom the main isolator, the phase line is routed to the RCCB (Residual Current Circuit Breaker), which protects against current leakage and electric shocks. The neutral line is connected to the neutral busbar through the RCCB. The RCCB ensures that any imbalance between phase and neutral due to leakage will trip the circuit .Distribution to SubcircuitsAfter the RCCB, the phase line is connected in parallel to the single-pole MCBs, which protect individual subcircuits from overloads or short circuits. Each MCB corresponds to a specific load, such as lighting, sockets, or appliances. The neutral lines from each subcircuit are connected back to the neutral busbar, ensuring a complete circuit .Earth ConnectionAll earth wires from the subcircuits are connected to the earth busbar in the distribution box. This provides a safe path for fault currents and enhances protection against electric shocks .Cable Sizing and SafetyThe main feeder cable should be sized according to the total anticipated load, while subcircuit cables are sized based on the specific load they serve. Proper insulation, secure connections, and adherence to local electrical codes are essential for safety .Summary of Connection FlowIncoming phase and neutral → Main isolator / double-pole MCBPhase → RCCB → MCBs → SubcircuitsNeutral → RCCB → Neutral busbar → SubcircuitsEarth → Earth busbar → Subcircuits This structured connection ensures safe distribution of electricity, protection against overloads, short circuits, and leakage, and allows easy isolation of circuits for maintenance or emergencies .