What happens if a secondary distribution box is not grounded

A secondary distribution box (subpanel) should generally not have its neutral bonded to ground, and in certain DC or specialized circuits, grounding may be intentionally omitted to ensure safety and code compliance.AC Subpanels and Secondary Distribution BoxesIn AC systems, a secondary distribution box, or subpanel, receives power from the main service panel. The neutral and ground must remain separate in the subpanel. The main service panel is the only point where the neutral is bonded to the ground and the panel enclosure. Bonding the neutral to the subpanel enclosure or grounding bus creates a parallel path for neutral current, which can energize metal parts and pose a shock hazard . Therefore, do not ground the neutral in a secondary distribution box; only the grounding bus should connect to the building's grounding system. Metal enclosures of subpanels should still be grounded to prevent shock from accidental contact with live wires, but this is separate from the neutral bonding . The grounding bus provides a low-impedance path for fault currents, stabilizes voltage, and protects against lightning or transient surges.DC Systems and Special CasesFor certain DC systems supplying premises, some circuits are explicitly not grounded. Examples include power supplies to contact conductors of electric cranes, hoists, circuits in hazardous anesthetizing locations, and electrolytic cell lines . In these cases, grounding could create unsafe current paths or interfere with sensitive equipment. Only circuits that require grounding for safety or code compliance should be connected to a grounding system.Key TakeawaysDo not bond the neutral to ground in a secondary distribution box; keep it separate from the grounding bus.Ground the metal enclosure of the subpanel to protect against accidental contact.Follow NEC guidelines (e.g., NEC 250.24(A)(5)) for separation of neutral and ground downstream of the main service panel.In specialized DC or hazardous circuits, grounding may be intentionally omitted to prevent unsafe conditions . Proper grounding and bonding ensure safety, prevent shock hazards, and maintain compliance with electrical codes. Always consult local regulations and a licensed electrician when installing or modifying secondary distribution systems.