Cable Type Name Lite Mid Heavy
Signal Wire 24-AWG 20-AWG 18-AWG
Power Wire 22-AWG 16-AWG 15-AWG
Connector type Micro Micro or Mini
Mini
Current Capacity 3-Ampere 4-Ampere 8-Ampere
or 8-Ampere
Maximum Backbone 100 250 250
Length Meters
Max. Drop Cable 6 6 6
Length Meters
NMEA-2000 Cable Standards
NMEA-2000 Cable Standards
The cable used in wiring NMEA-2000 network backbone wiring is now governed by the following specifications:
Re: NMEA-2000 Cable Standards
We look at the power distribution specifications and try to make some inferences. The maximum length of the network backbone is 300-meters or 328-feet. The maximum total power with LITE cable is 3-Amperes. We assume the power is inserted in the middle of the network. This means the farthest a device could be from the power insertion is 164-feet. We assume the power consumption on the network is split evenly between the two branches being fed, so the maxim power in one branch is half the total power, or 1.5-Amperes.
By specification, the maximum power a device on the network can draw from the network is 20-LEN, (or 1-Ampere). We assume that the worst case is this 20-LEN device is at the maximum distance from the power insertion point. For a network using LITE cable, the voltage drop that will occur in 164-feet of 22-AWG conductor when a current of 1-Ampere flows will be
Wire resistance = 16.14-Ohm/1000-feet x 328-feet = 5.3-Ohms
Current = 1.0-Ampere
Voltage drop = 5.3-Volts
According to NMEA specifications, the maximum allowed voltage drop if using 15-Volt power is 5-Volts, and we infer that the minimum voltage for a device is thus 10-Volts. From that we can calculate that the LITE cable would just about meet the specifications for power delivery at the maximum distance and maximum load characteristics, but the network would need a 15-Volt power supply.
If the network runs off a battery, and we assume only 12.0-Volts, NMEA says the maximum allowed drop is reduced to only 1.5-Volts. To keep our worst-case very-long network in compliance, we would have to reduce the power consumption of that most-distance (and only) device on one branch to be not more than 0.280-Ampere or 5-LEN. And, in all these calculations, that device would be the only device on that branch of the network.
In a typical small boat (less than 30-feet), the maximum distance from the power node to a device is probably about 15-feet. This suggests the maximum resistance of the 22-AWG power circuit would be
Wire resistance = 16.14-Ohm/1000-feet x 30-feet = 0.5-Ohms
With that resistance and with 12-Volt power, to reach a voltage drop of 1.5-Volts would require a current of
Wire resistance = 0.5-Ohm
Maximum drop = 1.5-Volts
Current = 3-Ampere
This suggests that there is really no need to use anything but LITE cable on a small boat, with one possible exception. If you have a tall mast and need to install a network-powered device at the mast head that consumes the maximum allowed 20-LEN (1-Ampere) you would have to pay attention to the wiring for that segment. To maintain not more than 1.5-Volt drop from 12.0-Volts with 1-Ampere using LITE cable, the maximum length of that circuit would be 51-feet.
By specification, the maximum power a device on the network can draw from the network is 20-LEN, (or 1-Ampere). We assume that the worst case is this 20-LEN device is at the maximum distance from the power insertion point. For a network using LITE cable, the voltage drop that will occur in 164-feet of 22-AWG conductor when a current of 1-Ampere flows will be
Wire resistance = 16.14-Ohm/1000-feet x 328-feet = 5.3-Ohms
Current = 1.0-Ampere
Voltage drop = 5.3-Volts
According to NMEA specifications, the maximum allowed voltage drop if using 15-Volt power is 5-Volts, and we infer that the minimum voltage for a device is thus 10-Volts. From that we can calculate that the LITE cable would just about meet the specifications for power delivery at the maximum distance and maximum load characteristics, but the network would need a 15-Volt power supply.
If the network runs off a battery, and we assume only 12.0-Volts, NMEA says the maximum allowed drop is reduced to only 1.5-Volts. To keep our worst-case very-long network in compliance, we would have to reduce the power consumption of that most-distance (and only) device on one branch to be not more than 0.280-Ampere or 5-LEN. And, in all these calculations, that device would be the only device on that branch of the network.
In a typical small boat (less than 30-feet), the maximum distance from the power node to a device is probably about 15-feet. This suggests the maximum resistance of the 22-AWG power circuit would be
Wire resistance = 16.14-Ohm/1000-feet x 30-feet = 0.5-Ohms
With that resistance and with 12-Volt power, to reach a voltage drop of 1.5-Volts would require a current of
Wire resistance = 0.5-Ohm
Maximum drop = 1.5-Volts
Current = 3-Ampere
This suggests that there is really no need to use anything but LITE cable on a small boat, with one possible exception. If you have a tall mast and need to install a network-powered device at the mast head that consumes the maximum allowed 20-LEN (1-Ampere) you would have to pay attention to the wiring for that segment. To maintain not more than 1.5-Volt drop from 12.0-Volts with 1-Ampere using LITE cable, the maximum length of that circuit would be 51-feet.