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D-49
Additional informations
Size of PEN protective conductor
Practical guidelines
The size of the PEN is determined in the same manner as a neutral conductor, i.e.:
for copper single-phase circuits or sized
y
16mm², it must be the same size as the
phase conductors
for copper three-phase circuits sized > 16 mm², it can be:
the same size as the phase conductors
smaller on the condition that:
the current likely to flow in the neutral during normal operation is less than the
permissible current for the conductor
the power rating of single-phase loads does not exceed 10 % of the total rating.
The conductor must be accessible to enable connections both in the factory and on
site, as well as checks on the tightness of connections.
b
b
v
v
-
-
Implementing the PEN protective
conductor
Practical guidelines
According to standard IEC 60439-1, the practical guidelines for implementing the
PEN are the following:
at the entry to the assembly, the PEN connection must be next to the phase
connections
within the assembly, the PEN does not need to be insulated from the exposed
conductive parts (except on sites where there is a risk of fire or explosion)
the size of the conductor must be at least equal to that of the neutral
the size must remain constant throughout the main busbars
the change from a TNC to a TNS system must take place at a single point in the
switchboard, via a marked neutral-disconnection bar that is accessible and can be
dismantled to facilitate the impedance measurement of the fault loop
after the TNS creation point, it is forbidden to recreate a TNC system.
The PE and the neutral must meet their specific requirements.
b
b
b
b
b
b
DD381655
Linergy PEN kit
see page B-73.
Designing the PEN conductor
Power circuit
Designing electrical
characteristics