TE Connectivity - Dorman Smith Forms of Separation

Switchboards - Forms of Separation Categories - Application Data

The principle of separation applied to multi-cubicle switchboards and panel boards is the achievement of a high degree of safety for equipment and people during normal operation and to promote safe working during commissioning and service. The resulting concept is one of functional separation and segregation of live parts of the system into sub-units by the use of barriers or partitions.

In general, separation should provide enhanced safety by:

• Protecting against contact with the live parts of adjacent functional units
• Preventing the passage of solid foreign bodies from one section of an assembly to an adjacent one

Various elements of an assembly must be considered for separation from neighbouring live sections, such as busbars, terminals and functional units. The specific form of their separation can be achieved in several ways according to the particular application and the requirements for access for maintenance. The minimum degree of protection to be achieved at each barrier or partition is to IP2X as specified in the Ingress Protection standard EN 60529.

Typically, this may include:

• PVC sleeving, wrapping or plastic coating of conductors
• Insulated terminal shrouds or PVC ‘boots’
• Rigid insulated barriers or partitions
• Compartments formed from earthed metal
• A device’s integral housing

There are several forms of separation, indicated by numbered category and subcategory; however the requirements for the degree of separation need to be carefully considered since the cost increases significantly with increased degree.

The principal categories are:

Form 1 – no separation

Typical applications are where the assembly is to be placed in a secure location and where failure will cause little or no additional disruption to other areas being supplied by that particular assembly.

Form 2 – separation of busbars from functional units

Applications may be similar to those of Form 1 but where it is important that a fault need not affect all functional units being supplied by the same busbar system.

Form 3 – separation of busbars from functional units and the functional units from one another, but not their terminations

This form should be applied where it is important to provide protection from internal live parts and where failure of functional units being supplied from the same busbar would cause unacceptable disruption.

Form 4 – separation of busbars from functional units and the functional units from one another, including their terminals

This form should be applied where it is important to provide protection from internal live parts and where failure of functional units being supplied from the same busbar would cause unacceptable disruption. Because all the terminations are separated, it is possible to isolate and work on a single functional unit.

Dorman Smith ‘LF-type’ panel board systems are supplied in Form 2 as standard, with Form 4 versions achieved with simple conversion kits. However, other separation forms can be provided in special cases.

With the exception of Form 1, the other separation forms have subcategories that permit permutations of the general form to be configured according to the requirements for specific applications and to allow the accommodation of different types of protection method. The exact form of separation provided on an assembly is a matter for agreement between the manufacturer and the end user.