Breaker and in-line fuse questions

[Radiozephyr]

I’m planning to install a i70s instrument pack, as well as a EV-200 autopilot, and I’ve run into a question I can’t seem to solve. I’ve decided that I’m going power the SeatalkNG backbone independently (i.e., not through the ACU-200) by running a SeatalkNG Power Cable from the iTC-5 to the “Instrument/Radar” breaker on my breaker panel. I plan to check the rating of that breaker, and will replace it with a 5 amp if it isn’t already (is that right?).

My question may seem a bit obvious, but I can’t seem to figure it out: how do I install a fuse for this connection? The manual is clear that “the distribution point should be fed from the vessel’s primary power source by 8 AWG cable,” and that it needs to be protected by a 5 amp fuse. However, I can’t find any in-line fuse holders that use 8 AWG cable and also can hold a fuse as small as 5 amp. Am I totally wrong to think that adding a fuse holder with a smaller gauge wire will create a bottleneck?

Also, the autopilot should be connected to a 20 amp breaker, correct?

Thanks!

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Radiozephyr,

Q1. I’ve decided that I’m going power the SeatalkNG backbone independently (i.e., not through the ACU-200) by running a SeatalkNG Power Cable from the iTC-5 to the “Instrument/Radar” breaker on my breaker panel. I plan to check the rating of that breaker, and will replace it with a 5 amp if it isn’t already (is that right?).

My question may seem a bit obvious, but I can’t seem to figure it out: how do I install a fuse for this connection? The manual is clear that “the distribution point should be fed from the vessel’s primary power source by 8 AWG cable,” and that it needs to be protected by a 5 amp fuse. However, I can’t find any in-line fuse holders that use 8 AWG cable and also can hold a fuse as small as 5 amp. Am I totally wrong to think that adding a fuse holder with a smaller gauge wire will create a bottleneck?
A1. The referenced 8 AWG cable would be used to supply power to the vessel's breaker / fuse DC electrical distribution panel. Lighter gauge wire would then typically be used to supply power to the vessel's individual marine electronics circuits. Should one desire to create a dedicated circuit to power the SeaTalkng backbone and should the vessel's breaker / fuse DC electrical distribution panel be able to accommodate a 5A breaker, then the SeaTalkng Power Cable would be connected directly to the electrical distribution panel ... this would be considered to be the best practice option.

However, should one desire to use one the the panel's higher amperage circuits to power power the SeaTalkng backbone, then you may want to consider connecting the heavier gauge wire exiting the panel to a bus bar having a pair of terminals capable of handling ring connectors capable of handling ring terminals for the heavier gauge wire and also having an additional smaller terminal(s) to accommodate other lower amperage circuits (ex. the 5A circuit for your SeaTalkng backbone) to be powered by the same breaker. In the case of such lower amperage circuits, they should each individually be protected with an fuse of the appropriate amperage rating.



Q2. Also, the autopilot should be connected to a 20 amp breaker, correct?
A2. This subject is addressed in section 4.4 ACU-200, ACU-300, ACU-400
connections of the Evolution EV-1 and ACU Installation Instructions. In the case of the ACU-200, the circuit which is supplying the ACU-200 with power should be protected with a 20A fuse or breaker.