The wiring of the distribution box is reversed incoming and outgoing wires are reversed

Reversing incoming and outgoing wires in a distribution box can compromise safety, reduce breaker effectiveness, and may cause malfunction in certain appliances or control circuits.Safety and Operational Risks

Reversing the supply (incoming) and load (outgoing) wires in a distribution box can create several issues:

• Circuit Breaker Functionality: Many low-voltage circuit breakers are designed with a specific orientation for incoming and outgoing wires. The moving and static contacts have different dielectric properties, and the arc behavior differs depending on the terminal. Reversing the wires may reduce the actual operating current below the rated value, potentially preventing the breaker from tripping correctly during overloads or short circuits .
• Reverse Polarity Hazards: If phase and neutral are swapped, appliances may continue to operate, but safety is compromised. For example, the outer metal parts of devices may remain live even when switched off, increasing the risk of electric shock. Control and automation circuits may malfunction, and single-pole breakers may fail to disconnect the live wire properly .
• Modern vs. Older Breakers: Some modern breakers are designed to allow reversed connections without affecting performance, while older breakers may have markings indicating "supply" and "load" sides. Reversing wires on these older devices can lead to damage or unintended tripping .

Corrective Measures

• Turn Off Power: Always switch off the main breaker before inspecting or correcting wiring. Use a voltage tester to ensure no current is present.
• Verify Wiring Diagram: Refer to the distribution box wiring diagram to identify correct incoming and outgoing connections. Ensure L1, L2, L3 (for three-phase systems) and neutral are connected to their designated terminals .
• Professional Inspection: If unsure, hire a licensed electrician to correct reversed wiring. They can ensure that all breakers, RCDs, and protective devices function as intended.
• Labeling and Documentation: After correction, clearly label supply and load sides, and update the wiring diagram for future reference.

Summary

Reversing the wiring in a distribution box is not recommended due to safety risks, reduced protection, and potential appliance or control system malfunctions. While some modern breakers tolerate reversed connections, the safest approach is to follow the manufacturer's wiring instructions and ensure proper orientation of incoming and outgoing wires .