Siemens SENTRON - Fault Protection (Protection against Indirect Contact)

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In the generally applicable standard for protection against electric shock
(DIN VDE 0100-410:2007-06, the use of residual current protective devices with
a rated residual current of ≤ 30 mA is required as additional protection for
• all socket outlets with a rated current of ≤ 20 A if they are intended for use by
non-experts and for general use
• nal circuits for portable items of equipment used outdoors with a rated current
of ≤ 32 A.
Note:
In DIN VDE 0100-410:06-2007, two exceptions from these requirements are
indicated but they are not usually applicable in the majority of applications.
The requirement of the standard for additional protection can be avoided only
in the case of socket outlets which are only used by qualied electricians and
persons who have received appropriate technical instruction (e.g. in electrical
workshops) or if it has been ensured that the socket outlet is only used per-
manently for a „specic item of equipment“.
According to standard DIN VDE 0100-723:2005-06 „Requirements for special
installations, locations or plants – classrooms with experimental equipment“,
Type B residual current protective devices with a rated residual current of
≤ 30 mA must be used for supplying power to the experimental equipment and
its circuits in TN or TT systems.
3.2 Fault protection (previously “Protection against indirect contact”)
Fault protection is understood to mean the contact of a human body with a part
that is not live in operation but is electrically conductive. In these cases, the de-
mand is for automatic disconnection of the power supply when a fault can pose
a risk due to the intensity and duration of the touch voltage.
Residual current protective devices with rated residual currents of over 30 mA
are also suitable for this purpose. The tripping conditions must be complied with
to achieve the protective effect. In addition, the dangerous touch voltage must
not be present for an impermissible length of time, taking into consideration the
grounding resistance and the rated residual current.
Protection through residual current protective devices