Det-Tronics R8471NH34001,2,3 Single Channel Gas Controller, NH3 - Manual (Page 9)

7 95-8529 1.1
Section II
System Installation
INSTALLATION
GENERAL WIRING REQUIREMENTS
NOTE
The wiring procedures in this manual are intended
to ensure proper functioning of the device under
normal conditions. However, because of the
many variations in wiring codes and regulations,
total compliance to these ordinances cannot be
guaranteed. Be certain that all wiring complies
with applicable regulations that relate to the
installation of electrical equipment in a hazardous
area. If in doubt, consult the NEC manual or
equivalent before wiring the system.
The use of shielded cable is highly recommended for
optimum RFI/EMI protection.
Moisture can have a detrimental effect on the
performance of electronic devices. Therefore,
it is important to take proper precautions during
installation to ensure that moisture will not come in
contact with the electrical connections or components
of the system.
If the installation does not use wiring conduit, the use
of properly installed water-tight glands is required
to prevent the entry of moisture into the device
enclosure.
When conduit is used, the use of conduit seals is
required. In addition to preventing the passage
of gases or flames through the conduit, seals can
prevent damage to electrical components caused by
condensation within the conduit.
To provide maximum effectiveness, conduit seals
should be used in conjunction with conduit drains and
breathers. In most applications, alternate changes
in temperature and barometric pressure can cause
“breathing”, which allows the entry and circulation of
moist air throughout the conduit. In most applications,
joints in the conduit system and its components are
not tight enough to prevent this “breathing”. Moisture
in the air can condense at the base of vertical conduit
runs and equipment enclosures, and can build
up over a period of time. This can be detrimental
to electronic devices. To eliminate this condition,
explosion-proof drains should be installed to bleed off
accumulated water.
Conduit seals must be watertight and explosion-proof
and are to be installed even if they are not required by
local wiring codes. A seal must be located as close
to the junction box as possible. In no case should
this seal be located more than 18 inches (46 cm) from
the junction box. When an explosion-proof installation
is required, an additional seal may be needed at any
point where the conduit enters a non-hazardous area.
Always observe the requirements of local codes.
When pouring a seal, the use of a fiber dam is
required to assure proper formation of the seal. The
seals should never be poured in temperatures that
are below freezing, since the water in the sealing
compound will freeze and the compound will not dry
properly. Contamination problems can then result
when temperatures rise above the freezing point and
the compound thaws.
The shielding of the cable should be stripped back
to permit the seal to form around the individual leads,
rather than around the outside of the shield. This will
prevent any siphoning action through the inside of the
shield. The shield should not be cut.
In applications where the wiring cable is installed in
conduit, the conduit must not be used for wiring to
other electrical equipment.