Board Types & Classifications

Overview

Distribution boards are classified by phase configuration, busbar orientation, physical mounting, form of internal separation and the fault level they must withstand. Choosing the correct type ensures safe power distribution, correct protection coordination and maintainability over the life of the installation.

In Kenya, single-phase consumer units are standard in residential premises while three-phase TPN (triple-pole and neutral) boards serve commercial and industrial loads. Type A boards use horizontal busbars for single-pole devices; Type B boards use vertical busbars for multi-pole heavy-duty loads.

Visual Classifications

Board Architecture In Practice

LoadPro Single-Phase Consumer Unit and Row Type Board

Type A • Single-Phase / SP&N

Single-Phase Consumer Units (Type A)

Horizontal busbar assemblies engineered for single-pole branch circuits in homes and small commercial units. Features 63 A – 125 A incomers, metal fireproof enclosures, and DIN-rail MCB/RCBO mounting.

BusbarsHorizontal 100A–125A

Voltage230 / 240 V AC

StandardIEC 61439-3

Loadcentre Three-Phase TPN Distribution Board

Type B • Three-Phase / TPN

Three-Phase TPN Distribution Boards (Type B)

Heavy-duty vertical busbar chassis supporting multi-pole and triple-pole outgoing MCCBs/MCBs. Ideal for commercial offices, plant distribution, and balanced phase load management.

BusbarsVertical 250A–800A

Voltage400 / 415 V AC

Fault Level25 kA – 50 kA / 1s

Form 4b • Segregated Cubicle

Form 4b Segregated Switchboard Lineups

Floor-standing cubicles with complete metallic physical segregation between busbars, functional breaker units, and external cable termination compartments for live maintenance safety.

SegregationForm 4b Type 6/7

Current800 A – 6300 A

Fault Level50 kA / 3s • 100 kA / 1s

Phase Classification

Single-Phase vs Three-Phase Boards

Parameter	Single-Phase (Consumer Unit)	Three-Phase (TPN Board)
Supply voltage	230 / 240 V AC, 1-phase + neutral	400 / 415 V AC, 3-phase + neutral, 50 Hz
Typical applications	Homes, apartments, small offices	Factories, hospitals, commercial complexes
Incomer options	63 A – 125 A isolator, RCCB or MCCB	160 A – 6300 A ACB, MCCB or switch disconnector
Outgoing devices	MCBs 6–63 A (B/C curve), RCBOs	MCCBs to 800 A, MCBs, fuse-switch units
Fault rating	6 kA – 10 kA	10 kA – 100 kA (ASTA / KEMA certified)
Busbar rating	100 A – 250 A tin-plated copper	250 A – 6300 A HDHC tin/silver-plated copper
Enclosure	1.2 mm sheet steel, wall-mounted	1.6–2.5 mm sheet steel, floor-standing or wall-mounted
Standard	IEC 61439-3 / BS EN 61439-3	IEC 61439-2 / BS EN 61439-2

Busbar Architecture

Type A vs Type B Busbar Orientation

Parameter	Type A Board	Type B Board
Busbar orientation	Horizontal	Vertical
Device polarity	Single-pole MCBs, RCBOs	Multi-pole MCCBs, fuse-switch units
Typical board	SP&N consumer units, row-type DBs	TPN distribution boards, sub-main panels
Load class	Light-duty final circuits (lighting, sockets)	Heavy-duty feeders (motors, sub-boards, plant)
Outgoing current	Up to 63 A per way	Up to 800 A per way

Internal Separation

Forms of Separation (IEC 61439-2)

Form	What is separated	Benefit
Form 1	No internal separation	Lowest cost; suitable for simple final boards
Form 2a	Busbars separated from functional units	Basic busbar protection during maintenance
Form 2b	As Form 2a plus terminals separated from busbars	Safer cable termination work
Form 3a	Busbars and functional units separated from each other	One unit can be maintained while others run
Form 3b	As Form 3a plus terminals separated from busbars	Cabling and device work isolated
Form 4a (Type 2)	Busbars, units and terminals all separated	Full isolation of each functional unit
Form 4b (Type 6/7)	As Form 4a plus outgoing terminals separated unit-to-unit	Maximum safety; required for critical facilities

Features

Key Features Across All Board Types

Type-tested / design-verified assemblies to IEC 61439 and certified by ASTA
Frames from 2.0–2.5 mm sheet steel; doors and covers from 1.2–1.6 mm sheet steel
HDHC tin-plated copper busbars with no-drill clamp connections
Standard IP43 ingress protection; IP54 and IP65 available on request
Epoxy powder-coated light grey RAL 7035 at 50–75 micron thickness
Tested for operation at 50 °C ambient temperature
Front or rear cabling access with removable gland plates and barriers
Modular frame widths of 400, 600, 800 and 1000 mm; depths of 800 or 1000 mm

Applications

Typical Applications

Residential estates and apartments Commercial offices and retail Factories and process plant Hospitals and healthcare Data centres and telecom Schools and universities Water and infrastructure Hotels and hospitality

FAQs

Type A boards use horizontal busbars designed for single-pole devices such as MCBs and RCBOs. Type B boards use vertical busbars that accept multi-pole (triple-pole) MCCBs and fuse-switch units for heavier loads. The choice depends on the outgoing device size and load characteristics.

Form 1 is acceptable for simple final boards. Form 2 is the minimum for sub-main boards where busbar contact during maintenance must be prevented. Form 3 and Form 4 are specified when individual functional units need to be worked on while adjacent circuits remain energised. Form 4b (Type 6/7) is required for hospitals, data centres and critical infrastructure.

Yes. TPN distribution boards with vertical busbars accept both single-pole MCBs and triple-pole MCCBs within the same enclosure, provided the busbar system supports both device footprints and the outgoing ways are correctly configured.

Indoor boards are typically IP31 or IP43. For sheltered outdoor locations, IP54 is the minimum. For exposed or washdown environments, IP65 is recommended. We configure the enclosure, gaskets and cable glands to meet the specified rating.

Board Types & Classifications