Emerson Rosemount 700XA, Reference Manual

Page: 53 / 294

• Use suitable lubrication for wire pulls in conduit to prevent wire stress.
• Use separate conduits for AC voltage and DC voltage circuits.
• Do not place digital or analog I/O lines in the same conduit as AC power circuits.
• Use only shielded cable for digital I/O line connections.
— Ground the shield at only one end.
— Shield-drain wires must not be more than two American Wire Gauge (AWG) sizes
smaller than the conductors for the cable.
• When inductive loads (relay coils) are driven by digital output lines, the inductive
transients must be diode-clamped directly at the coil.
• Any auxiliary equipment wired to the GC must have its signal common isolated from
earth/chassis ground.
NOTICE
Signal interference
If you don't follow this precaution, the data and control signals to and from the GC could
be adversely affected.
Do not place any loop of extra cable left for service purposes inside the GC purged housing
near the conduit entry for AC power.
4.3.3 Electrical conduit installation precautions
• Conduit cutoffs must be cut at a 90-degree angle. Cut conduits with a cold cutting tool,
hacksaw, or by some other approved means that does not deform the conduit ends or
leave sharp edges.
• Coat all conduit fitting-threads, including factory-cut threads, with a metal-bearing
conducting grease prior to assembly.
• Temporarily cap the ends of all conduit runs immediately after installation to prevent
accumulation of water, dirt, or other contaminants. If necessary, swab out conduits
prior to installing the conductors.
• Install drain fittings at the lowest point in the conduit run; install seals at the point of
entry to the gas chromatograph (GC) to prevent vapor passage and accumulation of
moisture.
• Use liquid-tight conduit fittings for conduits exposed to moisture.
When a conduit is installed in hazardous areas, follow these general precautions for
conduit installation:
• All conduit runs must have a fitting, which contains explosion-proof sealing (potting)
located within 3 in (76 mm) from the conduit entrance to the explosion-proof housing.
The seal should have a minimum IP rating of IP54 or equivalent NEMA
®
/Type rating on
the conduit sealing devices.
• The conduit installation must be vapor tight, with threaded hub fittings, sealed conduit
joints and gaskets on covers, or other approved vapor-tight conduit fittings.
Reference Manual Installation and start-up
2-3-9000-744 June 2022
Rosemount 700XA 53