[CA] [CA11] New installation multiple power inputs

[pfrank]

I have searched the forums and could not find a ready answer, so please forgive me if this is old news.

I recently had a Raymarine dealer install a new Evolution autopilot system, a p70 control head, a wheel pilot and an Axiom 9 to my 1995 32' sailboat . Since these were the first modern electronics on the boat (although my existing ST60+ Wind and Tridata instruments were integrated into the new system), the dealer installed both SeaTalkng and NMEA 2000 networks (which were interconnected).

Contrary to what I see in manuals and on these forums, the dealer installation included multiple power supplies to the networks. Fused power circuits were connected to 1) the ST60+ Wind (which was daisy chained to the ST60+ Tridata which was then connected to the Seatalkng backbone through an E22158 converter), 2) to the Seatalkng backbone itself, and 3) to the NMEA 2000 backbone itself.

To experiment, I pulled the fuses for both NMEA 2000 backbone and the ST60+ Wind and everything on the network still apparently works as it should. This seems to verify that I only need ONE power supply for the network (even if it is an interconnected SeaTalkng and NMEA 2000 network) AND the ST60+ instruments also get their power from the network as well.

My questions are:

A) Is there a reason why my dealer/installer would provide multiple power inputs as described?

B) What harm occurs from having multiple power inputs as described?

C) The power input to the NMEA 2000 backbone is an open circuit when the fuse is pulled. Should I pull that power cable off of its backbone connector and replace with a NMEA 2000 terminator?

Thanks!

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum pfrank,

Q1) Is there a reason why my dealer/installer would provide multiple power inputs as described?
A1) Some third party NMEA 2000 networking components utilize power conductors of insufficient wire gauge. Should such networking components be used within the system's powered and properly terminated SeaTalkng / NMEA 2000 backbone, then a second power insertion spur connected to the same circuit supplying the first may be installed.

Q2) What harm occurs from having multiple power inputs as described?
A2) A ground loop could be created. Ground loops may result in intermittent, erroneous, or no communications between devices which have been interfaced to the SeaTalkng network. As you have suggested, a single power insertion spur, located at the approximate midpoint of the backbone's LEN load, should be installed within the backbone. It is recommended that the power insertion to the ST60 instruments and second SeaTalkng / NMEA 2000 Power insertion be removed.

Q3) The power input to the NMEA 2000 backbone is an open circuit when the fuse is pulled. Should I pull that power cable off of its backbone connector and replace with a NMEA 2000 terminator?
A3) Negative. Termination plugs should only be installed within a backbone's two unoccupied backbone sockets (one at each end). Unoccupied SeaTalkng spur sockets should be filled with SeaTalkng blanking plugs to protect the socket.

[pfrank]

Thanks, Chuck, for your gentle reply. I should have been able to figure out on my own about ground loops and termination plugs vs blanking plugs. I am learning.

I have attached schematics showing my original installation and a proposed modified installation. We have already discussed removing the additional power sources as shown.

However, what about moving the Axiom 9 spur from the existing NMEA 2000 circuit to the STNG bus that exists right in the instrument pod? Any advantage in doing this? I have no idea why my installer originally went back to the NMEA bus, except that he saw the NMEA end on the Axiom 9 cable and thought that is where he had to go.

Of course, I could (and will) ask my installer about all of this, but want to be completely knowledgeable before I do.

Thanks again. You are THE MAN!

[Chuck - Raymarine - Moderator]

pfrank,

Q1. What about moving the Axiom 9 spur from the existing NMEA 2000 circuit to the STNG bus that exists right in the instrument pod? Any advantage in doing this?
A1. You're definitely on the right track here. When dealing with pedestal / pod mounted equipment, the object should be to pass as few cables / wires through the pedestal tubes as is permissible. Please click here to view a FAQ addressing expanding on this subject.

Q2. Comments on diagram:
A2. Regarding both diagrams, the NMEA 2000 backbone featuring the Fusion stereo components cannot be interfaced to NMEA 2000 backbone featuring the Raymarine component via a spur cable as is shown within your diagram. Please click here to view a FAQ addressing how these backbones may be joined to one another by using a SeaTalkng Backbone Cable and a field installable DeviceNet Micro-C plug of the correct gender to match the backbone socket of the end T-piece of the the NMEA 2000 backbone featuring the Fusion stereo. The resulting combined backbone would then feature two Termination Plugs ... one in the last backbone socket on the Raymarine side of the combined backbone and the other in the last backbone socket on the Fusion side of the combined backbone.

[pfrank]

Thanks, Chuck,

Regarding the Fusion stereo, I understand your point and see that the spur cable from STNG to NMEA is incorrect and should be a backbone cable instead.

Interestingly, the Fusion is currently controllable (still in my original wiring config) from the Axiom but maybe that is because both are currently connected with spurs to NMEA. Make sense?

[Chuck - Raymarine - Moderator]

pfrank,

Q. Interestingly, the Fusion is currently controllable (still in my original wiring config) from the Axiom but maybe that is because both are currently connected with spurs to NMEA. Make sense?
A. Results such as you have reported are not uncommon in incorrectly constructed SeaTalkng/NMEA 2000 backbones, but results vary and performance is generally unreliable.

[pfrank]

Again, many thanks, Chuck!

I have attached the final arrangement for my system (along with the original layout for reference). Changes are:

1) Remove power supplies to the ST60+ Wind and NMEA 2000 backbone, leaving only one power supply to the STNG backbone

2) Rewire the Axiom 9 from the NMEA 2000 backbone to the existing STNG converter in the instrument pod using an A06045 adapter cable

3) Wire the Fusion stereo directly to the STNG backbone using an A06075 cable

All this allowed me to remove a large chunk of wiring including the complete NMEA backbone and the incorrect spur formerly connecting the NMEA backbone to the STNG backbone.

Two days of hard sailing this past weekend and all worked great!

[Chuck - Raymarine - Moderator]

You're welcome.