Main & Sub-Distribution Boards

Incoming, metering and outgoing distribution in one coordinated assembly

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Main & Sub-Distribution Boards

Distribution boards in Kenya — frequently called consumer units in homes or triple-pole and neutral (TPN) boards in commercial settings — safely split an incoming electrical supply into individual protected circuits. We take the incoming supply, meter it, and distribute protected outgoing ways to sub-boards and plant.

Main distribution boards (MDBs) receive bulk power from the utility transformer or standby generator and house the master ACB or MCCB incomer, revenue metering, surge protection and outgoing feeders. Sub-distribution boards (SDBs) branch off the MDB to serve specific floors, wings or zones. Final distribution boards (FDBs) are the end-point consumer units delivering power directly to socket, lighting and machine circuits.

We size the busbar, incomer and outgoing devices from the load schedule and the prospective fault level. Sub-distribution and final boards are built to the same standard in wall-mounted, floor-standing or free-standing formats. OEM selection can be coordinated across ABB, Schneider Electric and CHINT ranges.

Distribution Assemblies & Lineups

Tier 1 · Primary intakePictured: ABB MNS Digital low-voltage switchgear and motor control lineup.

Main Distribution Switchboards (MDB)

ABB MNS Digital is pictured as a primary-intake and motor-control lineup reference. NPE project assemblies are specified from the load schedule, prospective fault current and operating conditions; the photograph does not establish a particular current, fault or separation rating.

RolePrimary intake

AssemblyIEC 61439-1 / -2 scope

RatingsProject-specific verification

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Tier 2 · Floor or zonePictured: NHP Concept Plus wall-mounted distribution panelboard family.

Sub-Distribution Switchboards (SDB)

The NHP Concept Plus family shows a wall-mounted panelboard with its accessory enclosure, suitable as a sub-distribution reference. This Australian AS/NZS 61439-3 range has isolator incomers up to 250 A or MCCB incomers up to 200 A; it is not a Form 4 main-switchboard lineup.

Isolator incomerUp to 250 A

MCCB incomerUp to 200 A

ReferenceNHP Concept Plus

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Tier 3 · Final circuitsPictured: Schneider Electric Easy9 EZ9EFS12CMCU consumer unit.

Final Distribution Boards (FDB) & Consumer Units

The Schneider Electric Easy9 EZ9EFS12CMCU is a 12-way single-phase metal consumer-unit reference for final circuits. MCB, RCD and RCBO selection, loading and enclosure configuration must be confirmed for the actual board.

ConfigurationSingle phase + neutral

ReferenceEasy9 · 12-way

ProtectionSelect per circuit

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Distribution Board Classifications

Selection item	Engineering requirement
MDB · primary intake	Main incomer and feeders; determine assembly current, fault withstand and separation from the project. ABB MNS is a lineup reference.
SDB · floor or zone	Distributes selected outgoing feeders. Pictured NHP panelboard family is not an 800 A / Form 4 assembly.
FDB · final circuits	Feeds lighting, sockets and equipment through selected MCBs / RCBOs. Pictured Easy9 is a single-phase consumer unit.

Main & Sub-Distribution Boards Specs

Selection item	Engineering requirement
Assembly standard	Determine the applicable IEC 61439 part and obtain design-verification and routine-verification records for the supplied assembly.
Current and voltage	From the approved load schedule, diversity, supply arrangement and service conditions.
Short-circuit performance	Prospective fault current, duration, protective-device coordination and assembly verification must agree.
Separation and access	Specify the required form and maintenance method. Internal separation does not authorise live work.
Enclosure and ambient	Specify IP rating, location, ventilation, temperature rise and cable access for the actual installation.
Photographs	Manufacturer references illustrate equipment classes; ratings are not inferred from appearance.

Inside the Box

Incomer / main switch — isolates the entire electrical supply to the board (ACB, MCCB or rotary isolator)
MCBs (Miniature Circuit Breakers) — protect individual circuits from overloads and short circuits
RCDs and RCBOs — detect earth leakage faults (typically 30 mA) to prevent electric shocks. Modern setups favour RCBOs for individual circuit isolation
SPDs (Surge Protection Devices) — Type 1 + 2 arresters protecting sensitive electronics from voltage spikes
Copper busbars — distribute the incoming live current across individual breaker switches, braced to the prospective fault level
Neutral and earth bars — return current to the source and channel fault current safely to earth
Discrimination study so a fault clears at the nearest device only
Surge protection, metering chamber and spare ways as specified

Key Features

Copper busbar sized and braced to the prospective fault level
Incoming ACB or MCCB with adjustable protection settings
Discrimination and cascading verified against manufacturer tables
Form 2 to Form 4b internal separation selected for the project; maintenance requires an approved isolation procedure
Type-tested to IEC 61439 with assembly-specific fault-level verification
Modular and bespoke options for fixed or withdrawable functional units
Front and rear access with top or bottom cable entry
Intelligent options including touchscreen HMI and Modbus / Ethernet communications

Typical Applications

Office and retail developments Factories and process plant Hospitals, schools and campuses Water works and infrastructure sites Data centres and telecommunications Residential apartments and estates Construction sites (temporary boards) Hotels and hospitality complexes

An MDB receives the primary incoming supply and feeds major outgoing circuits. An SDB distributes power to a floor, zone or group of loads. An FDB supplies final circuits such as lighting and sockets. Current and fault ratings are selected for the project rather than fixed by these names.

Either. We engineer from your single line diagram and load schedule, or build to an approved consultant design and issue GA drawings for sign-off.

Confirm the required form of separation, prospective fault current, duration and verification records for the actual proposed assembly. A reference photograph does not establish these ratings, and internal separation does not authorise live maintenance.

Typical lead time runs from drawing approval; standard boards are quicker than Form 4 lineups with imported ACBs. We confirm the programme with the quotation.

Testing requirements and records are agreed for each assembly. Ask the team to confirm the applicable IEC 61439 checks for your scope.

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Conceptual engineering scenes illustrate applications. Manufacturer reference photos are identified separately. Confirm exact models, dimensions and ratings before ordering.