10
65-2670-XX-04 M2A Transmitter Operator’s Manual
M2A Junction Box
The M2A’s cast aluminum junction box is dust and weather resistant. The junction box also protects
the M2A and all connections made to it. Use the three 3/4 NPT conduit hubs to wire the remotely
installed combustible gas detector and connect wiring from an external device, typically an RKI
controller. The top hub is shipped with a factory installed and sealed conduit plug to avoid leaks into
the junction box. If necessary, the conduit plug can be removed and the top hub can be used for wiring.
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. See “Wiring the M2A Transmitter” on page 18 for
complete wiring instructions.
Use the junction box’s two mounting holes to mount the M2A to a vertical surface at the monitoring
site. The window in the cover on the front of the junction box allows you to view the OLED display
and use the magnetic wand to actuate the magnetic control switches so you can perform non-intrusive
calibration. Removing the cover allows you to access the interior of the junction box.
Detector Junction Box
The detector junction box is intended to be installed remotely from the M2A junction box. The
detector is factory installed in the bottom 3/4 NPT conduit hub. A terminal strip is provided for wiring
connections and the detector is factory wired to one side of this terminal strip. The other side of the
terminal strip is for user-supplied wiring to the detector terminal strip located in the M2A junction box.
This wiring should go through the top 3/4 NPT conduit hub. Three spacers installed on the back of the
junction box controls the distance of the junction box from a mounting surface. A ground boss near the
top conduit hub provides an external earth ground connection.
Detector
The CT-7 style detector consists of the detector housing body, detector housing cap, cap gasket, and
the plug-in sensor.
The table below outlines the M2A part numbers and replacement detector part numbers for the
detectors.
Target Gas, Range
M2A Part Number
Detector Used
Cl
2
, 0 - 3 ppm
65-2670-CL2-04
65-2302-CL2
Cl
2
, 0 - 10 ppm
65-2670-CL210-4
65-2302-CL2-10
ClO
2
, 0 - 1 ppm
65-2670-CLO2-04
65-2302-CLO2
ClO
2
, 0 - 3 ppm
65-2670-CLO2-34
65-2302-CLO2-3
NH
3
, 0 - 100 ppm
65-2670-NH3-1-4
65-2302-NH3-100
NH
3
, 0 - 500 ppm
65-2670-NH3-5-4
65-2302-NH3-500
