Network Meter Block Installation, Operation, & Maintenance Manual
Pre-Installation Considerations 6
2.1.1.1 Division 2/Zone 2 Hazardous Area Considerations
If the user-supplied power supply will be mounted in a control cabinet located in a Division 2/Zone 2
hazardous area, it must be certified for use in that area. The complete system requires certification,
including but not limited to the evaluation of the NMB, power supply, connectors, fuses, internal wiring, and
routing that is required to complete the control cabinet or panel. The standards used for these hazardous
locations include UL ANSI/ISA 12.12.01 (Division 2) and EN/IEC 60079-7 or EN/IEC 6079-15 (Zone 2);
additional standards may apply.
The NMB is rated to be mounted in Class I, Division 2, Groups C and D or Zone 2 Ex ec IIB hazardous
locations with a temperature rating of T4 over the ambient temperature range of -40 °C to 60 °C. When
choosing a certified power supply, ensure it has been evaluated for shock and personal safety of ignition
hazard assessments, which include the maximum surface temperature expected during operation at
maximum-rated ambient temperatures.
2.1.2 External Fuse Protection
The NMB is equipped with a non-replaceable, internal fuse on the DC supply input to comply with required
safety standards. To protect the internal fuse, an external, user-supplied over-current protection (maximum
1.0 amp fuse) should be integrated into the DC power system installation wiring to the NMB.
2.1.3 Typical Wire Sizes
Typical wire sizes used when installing the NMB are as follows:
To maintain these ratings, the selected power supply must meet or exceed these ratings; otherwise, the
ratings of the overall system will be that of the power supply.
Table 2: Typical Wire Sizes
Equipment Number and Gauge of Wire
Belden Number or
Equivalent
Transmitters 4/18 gauge
4/20 gauge
9418
8404
Temperature probes and density/
pressure transmitters
4/22 gauge 8729 or 9940
Ethernet Cat 5 or Cat 6 1584A or 2412
DC power supply 2/20 gauge (maximum length of 750
feet/230 meters)
2/18 gauge (maximum length of 1,000
feet/300 meters)
2/16 gauge (maximum length of 1,500
feet/460 meters)
Maximum wire length accounts for point-to-point distance from the source to the device for supply
and return.
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