A1.5 Installation in an Ex t panel enclosure
within Zone 21 or Zone 22.
Installation of a BA307E-SS or BA327E-SS indicator
in an Ex t IIIC panel enclosure does not invalidate the
Ex t panel's certification as the front of both indicators
comply with Ex t impact and ingress requirements.
Although mounted in an Ex ta panel enclosure, the
BA307E-SS or BA327E-SS remain Group II, Category
1D Ex ia IIIC T80ºC Da IP20 apparatus and therefore
should be powered via a Zener barrier or galvanic
isolator as described in section 4.1 and 4.2 of this
manual.
Fig 22 Typical installation in Ex t panel enclosure
The Zener barrier, galvanic isolator or associated
apparatus is usually installed in the safe area, but
the inside of an Ex t enclosure is effectively a safe
area and the certified intrinsically safe interface
may therefore be mounted in the same Ex t panel
enclosure as the indicator.
The indicator terminals, the wiring to the indicator
and the intrinsically safe interface, if mounted
within the enclosure, should be segregated from all
other non-intrinsically safe wiring and equipment
within the panel enclosure as required by
EN 60079-11
Equipment protected by intrinsic
safety
and EN 60079-14
Electrical installations
design, selection and erection
.
If live maintenance is anticipated, it is
recommended that the Ex t panel enclosure should
be fitted with a warning label saying 'Do not open
when non-intrinsically safe circuits are energised',
alternatively all bare live non-intrinsically safe parts
within the panel enclosure should have an IP30
cover carrying a warning label 'Do not open when
energised'.
29
