Form 3b? Form 4aih? Ever wondered what your consultant is referring to when they talk about forms of segregation and don’t want to look stupid?
As defined by AS/NZS 61439 they are methods by which the busbars and functional units of an Assembly can be internally separated. The standard outlines 4 main Forms of Segregation:
- Form 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 – Separation of busbars from functional units and functional units of each other. Terminals of functional units are not separated from each other.
- Form 3b – As per 3a, but with the terminals separated from the busbar (and functional units).
- Form 4a– Functional units and terminals are separated from busbars and any other functional units and terminals.
- Form 4b – As per 4a, but with the terminals for each functional unit separated in their own space.
And you guessed it – the higher the number the higher the complexity.
A few definitions:
Assembly: a switchboard containing low-voltage switchgear/control gear.
Functional unit: a collection of electrical and mechanical components within an Assembly that contribute to the fulfilment of the same function. E.g. an individual motor starter within an MCC.
Busbar: Low impedance conductor to which several electric circuits can be separately connected.