FORM 3 PARTITIONING Separation of busbars from the  functional units and separation of  all functional units from one  another. Separation of the terminals for  external conductors from the  functional units, but not from  each other. Protection against contact with  live parts  Reduction in the risk of faults  between the functional units  (propagation of electrical arcs,  etc.).  The two types of Form 3  separation as defined by IEC  60439-1. Form 3a Terminals for external conductors  not separated from busbars. The functional units are  separated from each other and  from the busbars, but not the  terminals. Form 3b Terminals for external conductors  separated from busbars. The functional units are  separated from each other and  from the busbars. The terminals are separated from  the busbars, but not from each  other.
FORM 4 TYPE 2 PARTITIONING Separation of busbars from the  functional units and separation of  all functional units from one  another, including the terminals  for external conductors which are  an integral part of the functional  unit Protection against contacts with  live parts  Reduction in the risk of faults  between the functional units  (propagation of electrical arcs,  etc.).  There are seven types of Form 4  separation as defined by IEC  60439-1. Mertech offer the two  main examples as standard. Form 4 Type 2 (above) Terminals for external conductors  in the same compartment as the  associated functional unit. 
FORM 4 TYPE 6 PARTITIONING Separation of busbars from the  functional units and separation of  all functional units from one  another, including the terminals  for external conductors which are  an integral part of the functional  unit Protection against contacts with  live parts  Reduction in the risk of faults  between the functional units  (propagation of electrical arcs,  etc.).  There are seven types of Form 4  separation as defined by IEC  60439-1. Mertech offer the two  main examples as standard. Form 4 Type 6 (above) Terminals for external conductors  not in the same compartment as  the associated functional unit, but  in individual, separate, enclosed  protected spaces or  compartments.
Forms of Separation
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Forms of Separation