What is the max backbone length for a mid cable?

• A. 100 meters
• B. 75 meters
• C. 250 meters
• D. 500 meters

Answer: (C)

The backbone length for a mid cable is limited by the CAN bus electrical characteristics used in NMEA 2000. The mid-cable segment acts as the main trunk between devices and must maintain proper signal integrity and timing. Keeping this segment to 250 meters ensures the differential signals stay within spec, the voltages remain detectable, and reflections are minimized with the ends properly terminated. If the mid cable were longer, signal attenuation and timing skew could cause corrupted or lost messages, so 250 meters is the practical maximum. Shorter options would merely constrain how many devices or spurs you can place along the trunk, while a length like 500 meters would exceed what the network can reliably support.