FB Wiring Mainship 400

[Dougcole]

Hey All,


In a somewhat recent thread about Mainship's wiring practices, I lamented that the "Bridge Main" CB on my main panel doesn't seem to do anything at all. I got some good advice that I should look into the wiring under the helm so this weekend I spent some time under there with my multi meter.


What I found is that there are two pretty large single positive power posts mounted under the helm, one on the port side and one on the stb.



The port side post has a single cable going into it and a single wire going out. It is controlled by the bridge main CB. The switches on the port side are tied to this post. They are accessory items, spreader lights, courtesy lights, and the upper trim tab switches. Nothing with any sort of high draw that I can discern.



The stb side post also has a single cable coming in and a single wire out. It controls the switches on the stb side of the helm; electronics, engine start and shutdowns, battery combiner and the micro commander electronic throttles. It is not controlled by the "bridge main" CB, the "DC main" CB or either of the engine CB's. I couldn't find any way to shut down the power to that post. My guess is that it may be on a CB on the panel in the engine room, but I forgot to check there.


The throttles and engine switches are relayed through the other switches on the stb side, they are not tied directly to the stb post.


Any thoughts on this setup? I'd kind of like to be able to control everything on the upper helm with the bridge main CB, so I'm considering running everything to the port post, but I don't want to overload that breaker. I'd also like to be able to shut down the power to the upper helm when not in use without having to climb down into the ER.


Thanks,
Doug

 

[Comodave]

Why not just add a circuit breaker on the one that doesn’t have one? You can get surface mount breakers that would do the job. Just have to add a short jumper to power post. Just calculate what size breaker the wiring will support, size and length of wires.

 

[Dougcole]

Why not just add a circuit breaker on the one that doesn’t have one? You can get surface mount breakers that would do the job. Just have to add a short jumper to power post. Just calculate what size breaker the wiring will support, size and length of wires.

Isn't the CB supposed to be close to the power source, not the termination of the wire?

 

[DavidM]

I think that those upper helm, starboard side circuits are powered from the engine room panel. That is the way I recall it on my 2006 Mainship 34t.


Also there has to be some breaker in the circuit. I have heard of bone headed electrical systems, but I don't think even Mainship went that far. And yes any breaker is located near the source to protect the wiring all the way up to the devices.


David

 

[Comodave]

When I suggested adding a breaker up top, I was assuming that there is one at the source in the engine room. Then you could use the breaker up top as basically a switch. It may be more difficult to find a switch that would be rated for say 40 or 50 amps other than a battery switch. A surface mount circuit breaker would be much smaller than a battery switch so it may fit more easily.