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Chapter 3: Installation & Startup
65-2646XL-05-04 M2A Transmitter Operator’s Manual
Wiring the M2A to a Controller and Alarm Devices
WARNING: If the controller’s construction is not explosion-proof, the controller must be
installed in an ordinary location. Do not install a non-explosion-proof controller
in a classified location.
If the controller’s construction is explosion-proof and the controller is installed
in a classified location, install a conduit seal at the controller’s wire entry
location that is consistent with the controller’s explosion-proof rating.
1. To maintain the explosion proof classification of the M2A junction box, a conduit seal must
be installed within 2 inches (for Group B environments) or 18 inches (for Groups C and D
environments) of the M2A’s left conduit hub, in addition to the conduit seals shown in Figure
8. Adhere to your local electrical code when installing the conduit seal.
2. Guide multi conductor shielded cable or cables or wires in conduit through the left conduit
hub of the M2A junction box. The number of cables or wires needed will depend on whether
the M2A is wired to a gas monitoring controller or just to power, whether any relays are used,
and whether the Modbus output is used.
WARNING: If the top conduit hub is used for wiring, be sure to seal the threads to ensure
water does not enter the junction box. A conduit seal, which is normally
required to maintain the junction box’s hazardous location rating, will also
help to prevent water from entering through the top port.
NOTE:
If the M2A is being wired to a PLC or DCS device, see “Appendix B: PLC
and DCS Device Wiring” on page 62, then continue with step 8.
Use the following recommendations to determine how to wire the M2A:
• If Modbus connections will not be used and only the PWR/SIG connections will be used,
use a two or three conductor shielded cable or two or three wires in conduit for
connections to the power/signal terminal strip depending on whether or not the signal (S)
terminal is used. The S terminal has a 4 - 20 mA output, but if you do not need to monitor
this signal and do not connect to the S terminal to access this signal, the M2A will still
function completely.
Table 3: Wire Size for PWR/SIG Connections
Max Distance to
Controller
w/18 Gauge Wire
Max Distance to
Controller w/16 Gauge
Wire
Max Distance to
Controller w/14 Gauge
Wire
2,500 ft.
5,000 ft.
8,000 ft.
