Form 4b Type 7 Mains Distribution Assembly, 1600A

Overview

Throughout 2025 we saw a high level of interest in high current Mains Distribution Assemblies with segregation to Form 4b Type 7. Towards the end of the year we completed a suite of assemblies for a project in the North-West of England, which included a fully loaded 1600A Form 4 assembly, supplying this critical infrastructure project.

The incoming arrangement consisted of an automatic changeover system, which comprised a pair of electrically and mechanically interlocked 1600A 4P MCCBs controlled by a Schneider UA controller. The system is to be biased to mains and will have a permanently connected, fully rated, stand-by generator. The incoming arrangement also incorporated an ABB / Furse surge protection device, providing Type 1, 2 and 3 protection in accordance with BS EN IEC 61643. Incoming test sockets were also incorporated allowing a range of installation tests to be completed without the need to remove any shield plates.

On the outgoing side, the assembly incorporated an array of 160A, 250A and 400A 4P MCCBs, each with variable, Type A RCD protection. Each outgoing way was individually metered and web enabled. The assembly also incorporated a 250A 4P MCCB to receive a supply from a PV array. The “PV” incoming MCCB can be re-purposed as an outgoing way and is provided with variable RCD protection, which is keyswitch controlled i.e. the RCD protection is inactive when the MCCB is used as the PV incomer but can be activated if used as an outgoing way. The meter for this circuit is bi-directional. Each outgoing compartment also incorporated test sockets allowing the RCDs to be safely tested without the need to remove any covers or shield plates.