Fault Protection (Previously "Protection Against Indirect Contact") - Siemens SENTRON Manual

Note
While DIN VDE 0100-410:06-2007 specifies two exceptions to these require-
ments, these are not generally applicable to 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 qualified 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 permanently for a "specific 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 measures to protect against the contact of
a human body with a part that is not live in operation but is electrically conductive.
In these cases, the demand 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.
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