Owner's Manual

Powertap can handle large loads as long as no more than 8
amps is drawn through any single segment of the trunk line.
However, cable resistance may limit your application to less
than 8 amps.
3.3 Micro/Mid Power Connection
Like the Mini power connection, power is supplied to a Micro/
Mid trunk line via a Powertap, which is shown in Figure 5.
3.4 Micro/Mid Power Capability
Micro/Mid cable is rated to 4 amps but like Mini cable,
strategic placement of the power source could support
higher current. For example, 8 amps of power could be
supplied to the middle of the trunk where 4 amps is supplied
to both sides of the power tap. It can handle large loads as
long as no more than 4 amps is drawn through any single
segment of the trunk line. However, cable resistance may
limit your application to less than 4 amps
3.5 End-Powered Network
End-powered networks are typically seen on smaller vessels
with only a few NMEA 2000
®
devices. Figure 6 shows an
end-powered network.
3.6 Middle-Powered Network
A middle-powered network is typically found on larger
vessels and is any network where the power is connected
to the network at some location other than at the end. This
network consists of two legs, one leg extending in each
direction from the power insertion point. Figure 7 shows a
middle-powered network.
3.7 Maximum Power Supply Voltage Drop
The NMEA 2000
®
network is designed to work properly
as long as there is no more than a 1.5 volt difference in
the power supply voltage between any two devices on
the network. Therefore, you should perform an estimate
of the voltage drop across a network using the
following equation:
Voltage Drop = 0.1 x Network Loads x Network Length x Cable Resistance/100
Where: Network Loads is sum of Load Equivalent Numbers (LEN)
for all devices (see device nameplate)
Network Length is in meters
Cable resistance is in ohms/100 meters
Power supply voltage drop estimates resulting in less
than 1.5 volts across the entire network require no further
analysis. Likewise, estimates ranging between 1.5 and 3.0
volts require no further analysis as long as a mid-powered
network is used. Occasionally, estimated power supply
voltage drops will occur outside these limits and will require
further consideration through detailed calculations by
certified technicians.
4. Ground the Network
The NMEA 2000
®
network should be grounded at ONE
Figure 6
End-Powered Network
114
5 meters 20 meters 5 meters 3 meters 0.3 meters
Speed Log
3 meters
2 loads
TRTR
3 meter
2 loads
Depth Repeater
3 meters
2 loads
Compass Display
2 meters
1 load
Electronic Compass
Autopilot
1 meter
1 load
Power from
Battery
TR
Trunk Line
Drop Line
Device or Node
Drop Tee
TR TR
Depth Sounder
3 meters
2 loads
3 meters
2 loads
2 meters
1 load
Compass Display
3 meters
2 loads
Electronic Compass
2 meters
1 load
Speed Log
10
meters
2
meters
5
meters
3 meters 3 meters
Autopilot
Power from
Battery
TR
Trunk Line
Drop Line
Device or Node
Drop Tee