Legrand Main Distribution Board (MDB)

The Legrand Main Distribution Board (MDB) combines Legrand’s XL³ enclosure architecture with DPX3 and DRX moulded-case breakers and Viking terminal blocks to deliver IEC 61439 compliant LV main distribution assemblies for commercial and light-industrial distribution. Standard XL³ modular enclosures provide catalogued type-tested busbar kits and temperature-rise verification up to 4000 A; engineered, type-verified busbar systems can be supplied to reach the panel specification of up to 6300 A. Short-circuit withstand (Icw) is typically engineered between 50 kA and 100 kA (1 s) depending on busbar sizing, bracing and fault loop impedance and is verified by routine and type tests per IEC 61439-2. Incoming ACB/ACB-like solutions are integrated with protection and metering interfaces; outgoing feeders use DPX3/DRX MCCBs with adjustable thermal-magnetic and electronic trip units to implement selective coordination and earth-fault/residual current protection. Viking terminal blocks provide standardized cable termination, potential distribution and finger-safe links that facilitate Forms of Separation from Form 2b through Form 4b per IEC 61439-1/2. Design verification follows the IEC 61439 test and routine regimes: temperature rise of busbars and connections, short-circuit verification (Icw/Ipk), dielectric/clearance tests, mechanical operation and where specified internal arc testing per IEC 61641. Protective device selection and coordination are executed to IEC 60947 series requirements for low-voltage switchgear and controlgear (IEC 60947-1, -2 for circuit-breakers). Typical applications include main incomer and transformer secondary distribution in data centers, hospitals, high-rise buildings, shopping centres and light industrial plants where modularity, repeatability and maintenance access are critical. Environmental protection can be supplied from IP31 for indoor plant-room installations up to IP54 (and higher with custom enclosures) in accordance with IEC 60529. Optional energy metering, local HMI and remote telemetry gateways are provided for power monitoring and integration into BMS/EMS using common protocols. In short, Legrand MDB assemblies based on XL³, DPX3/DRX and Viking accessories offer a type-tested, modular platform meeting IEC 61439 verification requirements suitable for primary building distribution and secondary power distribution roles.