65-2662XL-04 M2A-XL Transmitter
Chapter 2: Description
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9
M2A-XL Junction Box
The M2A-XL’s cast aluminum junction box is dust and weather resistant. The junction box also
protects the M2A-XL 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-XL Transmitter” on
page 19 for complete wiring instructions.
Use the junction box’s two mounting holes to mount the M2A-XL 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-XL junction box.
The H
2
S 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-XL 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.