Which statement is true about backbone lengths for mid and heavy cables?

• A. Only mid has a maximum backbone length of 250 meters
• B. Only heavy has a maximum backbone length of 250 meters
• C. Both mid and heavy have a maximum backbone length of 250 meters
• D. Neither mid nor heavy have a backbone length of 250 meters

Answer: (C)

Backbone length is the length of the main trunk of an NMEA 2000 network, chosen to keep the CAN signaling reliable and within the timing and impedance requirements of the bus. Both mid and heavy cable types are specified to support a backbone length up to 250 meters, so the maximum trunk distance is the same for either, as long as the network is terminated correctly at both ends and other North American terms (like spur lengths and device count) are respected. The heavier cable mainly affects power delivery and voltage drop for devices powered from the bus, not the backbone’s maximum distance. So the true statement is that both mid and heavy have a maximum backbone length of 250 meters.