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A1.3 Installation in an Ex p panel enclosure
within Zone 2.
Fig 21 shows a typical installation within an Ex p
pressurised enclosure located in Zone 2.
The BA307NE and the BA327NE may be driven
directly from any instrument with a 4/20mA output
located in the safe area or from apparatus located
within the Ex p panel enclosure.
There are five design requirements:
1. The indicator must be installed in the panel of
an Ex p enclosure generally as shown in
section 5 of this manual and in Fig 21.
2. The four vents at the rear of the indicator
enclosure shown in Fig 22 must not be
obstructed.
3.
The certificate specifies that the indicator
should be connected to a
limited energy
4/20mA circuit having a maximum output
current of 200mA. An instrument located in
the safe area that is safe in normal operation
and has a 4/20mA output suitable for live
connection i.e. CE marked, is usually
considered acceptable.
4. Wiring should comply with Clause 9 of
BS EN 60079-14:2008.
5. The 4/20mA input must be able to supply the
1.2V required to operate the indicator. This
increases to 5.0V if the indicator includes an
optional loop powered backlight. See 9.5.1
Fig 22 Position of rear vents
