Page 614 - Wago_Rail-MountedTerminalBlockSystems_Volume1_2015_US.pdf

14 – Continued –
General Technical Information
612 for Electrical Equipment in Hazardous Areas
Harzardous Environments perature, arcs or sparks may cause an According to EN 1127-1 and all other
Hazardous environments are areas in explosion. These may take form as gases, related standards that are commonly
which the atmosphere may become vapors or mixtures with air under atmos- known, hazardous areas are divided into
explosive. An explosive atmosphere is a pheric conditions in critically mixed ratios zones according to the likelihood of the
mixture of flammable substances in the such that excessive high temperature, occurrence of an explosive atmosphere
form of gases, vapors or mixtures with air arcs or sparks may cause an explosion. as follows:
under atmospheric conditions in critically
mixed ratios such that excessive high tem-

Hazardous areas resulting from flam-
mable gases, vapors or mist

Zone 0
Areas in which a hazardous, poten-
tially explosive atmosphere is present
permanently, for long periods or fre-
quently.

Zone 2 Zone 1
Areas in which hazardous, potentially
explosive atmospheres are likely to
occur “occasionally” during normal
operation.
Zone 0
Zone 2
Areas in which hazardous, potentially
Zone 1
Zone 1 explosive atmospheres are likely to
occur “rarely” or “short-term” during
Zone 0 Zone 0 normal operation.

Hazardous areas due to combustible
dust

Zone 20
Area in which an explosive dusty
Zone 22 atmosphere is present “permanently,”
for “long periods” or “frequently” and
in which deposits of combustible dust
of unknown or excessive thickness may
be formed. Dust deposits alone do not
constitute a Zone 20.
Zone 21
Area in which an explosive dusty atmo-
sphere is present “occasionally” under
normal operating conditions and in
Zone 21 which deposits or layers of combustible
dust can generally be present.
Zone 20 Zone 22
Area in which an explosive dusty
atmosphere is not likely to occur dur-
ing normal operation and, if it occurs,
will only exist for a “short period”, or
in which accumulations or layers of
flammable dust are present.