What is the max backbone length of a heavy cable?

• A. 200 meters
• B. 100 meters
• C. 300 meters
• D. 250 meters

Answer: (D)

In NMEA 2000, the backbone is the main trunk of the network, and its length is limited to keep the CAN signaling reliable across all devices connected to it. Heavier cable has lower resistance and less signal loss, so it allows a longer trunk than lighter cable. The standard specifies that the maximum backbone length for this heavier cable is 250 meters. This limit helps ensure the propagation time along the trunk stays within the network’s timing and termination requirements, so messages aren’t distorted or lost as they traverse the full length. Exceeding this length would risk signal integrity and timing issues, which is why 250 meters is the accepted maximum for heavy backbone. The other options represent shorter limits or limits for lighter cable, not the maximum for heavy cable.