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
Terminals for external conductors
not in the same compartment as
the associated functional unit, but
in individual, separate, enclosed
protected spaces or
compartments.
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 2
Terminals for external conductors
in the same compartment as the
associated functional unit.
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
