Mpower Bypass Module + Fuse Pack/Jumper

Maretron MPower CBMD12-R 12-Channel Bypass Module with Jumper Wire and Fuse Pack

A manual override panel that gives you physical switch control over every CLMD12 load circuit if the NMEA 2000 network fails or the CLMD12 itself malfunctions — 12 Carling Curvette rocker switches, individual ATC fuse protection per channel, and no arcing during override.

Why It's Worth It
Digital switching systems are only as reliable as the network and electronics that control them — which is exactly why a bypass module exists. If the CLMD12 loses network communication or fails entirely, the CBMD12 lets you unplug the J1 connector from the CLMD12 and plug it into the CBMD12 instead, giving you direct switch control over every load with no network dependency. The Carling Curvette rocker switches are purpose-built for marine environments (corrosion, temperature, vibration, and shock rated) and produce no arcing during switching — a safety consideration in a bilge or fuel vapor environment. ATC fuse protection per channel uses the same current ratings as the CLMD12 outputs, and the fuse slot markings eliminate the need to cross-reference a chart to install the right fuse. Importantly, bypass does not require moving or removing fuses — a common degradation point in other bypass approaches.

Important Limitations
The CBMD12 does not support paralleled outputs or PWM dimming — if your CLMD12 installation uses paralleled circuits or dimmable lighting, those features are unavailable in bypass mode. Each circuit is controlled by a separate switch only.

Use
Install adjacent to or near the CLMD12. In normal operation, the CBMD12 sits unpowered and unused — it's strictly a backup. To activate bypass: ensure area is free of fumes, set all CBMD12 switches to OFF, connect DC power to the 1/4"-20 stud, unplug J1 from the CLMD12, and plug J1 into the CBMD12. The included red 6AWG jumper wire (A3720) connects the CBMD12 to the CLMD12's main DC (+) source when mounted adjacently. Switch labels on the CBMD12 correspond to CLMD12 breaker numbers — not sequential left-to-right — so use the label under the ABS cover to identify which switch controls which load.