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Semi-Modular Form2 to Form 4b Enclosures

ECBOX electrical metal enclosure box, outdoor metal enclosure box and industrial enclosures are 100% modular structures for Power Control Centre, Motor Control Centre & PMCC solution Flexible compartmentalized up to form4.

Enclosure Box India

IEC 61439 Switchboard Solution

IEC 61439 'Low-voltage switchgear and control gear assemblies specifies standard arrangements of switchboard (call forms of internal separation).

They are labelled as Form 1, Form 2, Form 3 and Form 4. Forms 2, 3 and 4 are further broken down into Form 2a, 2b, 3a, 3b, 4a and 4b.

Each Form relates to the internal separation of the busbars, functional units and terminals, each being defined as:

  • Busbar - low impedance conductor to which several electric circuits can be connected

    • Main busbar - busbar to which one or more distribution busbar, incoming unit or outgoing unit can be connected

    • Distribution busbar - busbar in one section which is connected to the main busbar from which incoming or outgoing units can be connecte

  • Functional Unit - part of the assembly comprising the electrical and mechanical elements that contribute to the fulfilment of the same function

    • Incoming unit - a functional unit which feeds energy into the assembly

    • Outgoing unit - functional unit supplying power to the outgoing circuits


  • Terminals - part of the assembly which provides for connection of incoming and outgoing cable and busbar

Forms of Seperation

Internal separation is achieved by using barriers or partitions (including metallic or non-metallic), insulation of live parts or an integral housing (i.e. moulded case circuit breaker). The internal barriers should provide protection against contact with IP XXB and against the ingress of foreign bodies to at least IP 2X.

Form 1 has no internal separation between, while Form 4b has the greatest with busbars, functional units and terminals all being separated

(see illustration):

Types of Seperation

Forms of separation from 1 - no internal separation of the busbars, functional units and terminals from each other.

  • Form 2a - separation of the busbars from the functional units. Terminals are not separated from the busbars.

  • Form 2b - as for 2a, but the terminals are not separated from the functional units.

  • Form 3a - separating the busbars from the functional units and each functional unit from the other units. The terminals of each functional unit are not separated from each other. Terminals are not separate from the busbars.

  • Form 3b - as per 3a, but with the terminals separated from the busbar (and functional units)

  • Form 4a - separation of the busbars from the functional units and each functional unit from the other units. Separation of the terminals for a functional unit from the busbars and those of any other unit. Terminals enclosed in the same compartment as the functional unit.

  • Form 4b - as per 4a, but with the terminals for each functional unit enclosed in their own space.

Features & Specification

  • 100% Modular Structure; can be dispatched into a pack.

  • Flexible Horizontal/ Vertical busbar and Cable Compartment Configuration.

  • Compartmentalised - up to Form 4 IP 54 with a polyurethane foam gasket.

  • Doors are available in heights of 200mm & multiplies of 100mm.

  • Horizontal Busbar chambers, Vertical cable chambers are provided with Individual bolted cove Rear bolted covers.

  • Plinth (modular) & Side cover (Optional.)

  • Wide Variety of Standard MCC ranges.

  • Additional accessories like Cable support, Busbar Support and Baying kit are available.

  • Double front execution can also be provided.

  • Lifting Channel provided as standard (instead of Eye-bolts) for higher load-carrying capacity.

  • Bus Bar chamber (Top/ Bot) and Feeder doors (Left/ Right) are interchangeable.

  • Doors are openable with hinges for 120-degree opening and Metal locks.

  • The panel can be expanded in all 3 dimensions and bayed together using Baying Kit.

  • All corner bars and crossbars can be placed at25mm intervals horizontal, vertical, and longitudinal.

  • Horizontal & vertical separation plates are provided between all feeder compartments.

  • Colours: RAL-7035 (structure finish) for structure, covers & doors.

  • RAL-2000 (smooth finish) for Mtg. Plate, RAL-9000 (smooth finish) for Plinth and lifting channel.

  • Sheet thickness 2.0mm GPSP for Structure, 2.0mm CRCA for mtg plate & mtg rail, 1.6mm CRCA for Covers & Doors, 1.2mm CRCA for Separation Plates.

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