Network Meter Block Installation, Operation, & Maintenance Manual
Installation 13
• For wiring systems using conduit, an Ex d certified sealing device must be used immediately at the
entrance of the enclosure. Any unused entry must be suitably blocked with an Ex d IIB IP66 certified
plug for ATEX and IECEx applications. For North American zone applications, the plug must be listed
close up type.
• Wiring and cable glands must be suitable for 80 °C operation.
• Equipment bonding should be provided at the external grounding facility terminal; external connection
is not required when using metallic conduit or armored cable. The external grounding facility terminal
wire range is 10 to 12 AWG (4 mm
2
minimum).
3.2.4 ATEX and IECEx Zone 2 Installations
Although NMB models purchased with an explosion-proof instrument housing (with “XP” or “SS” in the
model code) are certified for Zone 1, they also may be installed in a Zone 2 area using Zone 2 wiring
practices. The appropriate zone check box is required to be marked on the instrument housing’s name
plate to indicate which zone area wiring methods were used during the installation.
The following information is specific to NMB models purchased with an explosion-proof instrument housing
that will be installed in ATEX and IECEx Class I, Division 2, Zone 2 environments:
• The input power terminal block is rated for a wire size range of 14 to 28 AWG (0.2 mm2 to 1.5 mm2).
• The tightening torque is 0.2 to 0.25 N∙m (1.7 to 2.2 inch-pounds or 28 to 35 inch-ounces).
• The minimum wire temperature rating is 80 °C operation.
For NMB models that are panel mounted (with “PM” in the model code):
• The NMB should only be used in an area of not more than pollution degree 2, as defined in IEC/EN
60664-1.
• The NMB should be installed in an enclosure that provides a degree of protection not less than an IP54
rating in accordance with IEC/EN 60079-0 standards and only be accessible with the use of a tool.
For NMB models purchased with an instrument housing (with “XP” or “SS” in the model code):
• The area inside the instrument housing should maintain a pollution degree of 2, as defined in IEC/EN
60664-1.
• To minimize the risk of electrostatic charge, provisions should be made for adequate grounding and
equipment should be installed in such a manner that accidental discharge should not occur.
• Any cable glands, thread adapters, or sealing fittings used should be certified Ex e, at a minimum.
To prevent the ignition of hazardous atmospheres, disconnect from the power supply before
opening the instrument housing. Keep the housing tightly closed when circuits are alive.
The NMB contains an internal battery-powered circuit; to prevent the ignition of hazardous
atmospheres, do not open the housing unless the area is known to be non-hazardous.
To reduce the risk of ignition of hazardous atmospheres, conduit runs must have a sealing fitting
connected within 2 inches (50 mm) of the housing.
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