Relationship between fuse block and switch panel breakers

M

Marco Flamingo

Active member
I'm putting my electrical system back together and I'm not sure if the prior owner had things set up correctly. And I'm not sure how the fuse block works with the switch panel (both of which appear to be stock on the CD 16).

The switch panel doesn't seem to be still produced by Blue Seas. It has 6 switches (cabin lights, radio, depth sounder, etc.). It has reset breakers that aren't marked, but the present Blue Seas panels are all 15A breakers.

The separate fuse panel holds 6 blade fuses and has a negative bus bar. It was basically unused. I think the prior owner added a lighted compass and a cigarette style plug-in (that wasn't fused).

There were a couple of in-line "add-on" fuses of the AGC glass tube variety and some spares on board. For instance, the positive wire coming from the depth sounder switch had an inline fuse.

The setup seems a little clunky. What does a 15A breaker do for the depth sounder switch when a 3A inline fuse is still needed? And the nearly empty fuse block could have a 3A blade fuse in one of the slots, but how to integrate this (if needed).

I'm just trying to simplify, simplify. Maybe the 15A breaker for the depth sounder could be (or has been) replaced by a 3A breaker and the inline fuse wasn't needed? Maybe all 6 of the connections in the fuse panel were for use in adding aftermarket gadgets?

Mark
 
Yes, often the wiring in the C Dory is confusing, and not consistent from boat to boat.

Generally those circuits with switches are protected by the breaker on that circuit. The size of the fuse, is generally keyed to the size of wire, or max current which will be run thru that circuit.

In some cases, there are electronics which "require" that a separate smaller fuse be put in place. This is the reason that there is a 3 amp fuse, in line with the depth sounder. Is it necessary? Yes, because if there is a current draw more than 3 amps, it means that there is a problem (short) in the depth sounder, and thus the fuse should protect the circuit (and boat from fire).

Many of the boats, will have a circuit which has "instruments". In that case, then each GPS, Radio, Fish Finder, Radar, should have its own fuse, but you will run all of these devices off the one switch. You may want to turn all of the instruments on and off. But for example. for my current Garmin radar, I don't want the radar scanner turning, if I am running the depth sounder and GPS for an anchor alarm. Thus, I put in a separate switch for the radar.

How to handle the fuses? I like to either put in another fuse panel, or expand the size of the panel available. In my current C Dory I put in two of the 12 fuse blocks:
k2-_cde7e905-41a5-4320-96d6-38f1200b3393.v1.jpg


This allows each circuit/device to have its own fuse, and gets rid of the "dangling" fuses.

I also added additional switches. For example, the above radar. Also I have several extra LED lights: one is a forward flood light, one is a cockpit light, one is an interior red LED as a night light. I can reach these switches from the bunk, since they are down low on the panel, and if I want a red light before I get up in the middle of the night, i push the switch--same if I want floodlights.
 
Then it looks like most of my equipment was wired correctly but maybe not the simplest method.

It just seems odd. I turn on my plotter dash switch, which has a 15A breaker. Because the breaker is so large, I also have an inline fuse right behind the 15A breaker. And turning on the plotter dash switch doesn't do anything, I still have to turn on the plotter. Meanwhile, I have a slightly smaller fuse block than shown in your picture, which could easily hold the plotter fuse in one of the unused slots (only one of 6 is used). I would still just turn on the plotter at the plotter.

It seemed like the only advantage of wiring my plotter through the dash breaker system is that there is a red light that shows when the plotter might still be on. But then I did a little more research and found that Blue Seas makes smaller breakers (http://www.pbsboatstore.com/Blue-Sea-Sy ... fgodL6UL6Q). The picture shows a 15A breaker (which comes standard with the Blue Seas breaker switch panel like I have), but 3A, 5A, 7A, and 10A breakers are available.

It looks like C Dory simply doesn't customize the Blue Seas breaker panel to fit the equipment (if they even know what the first owner wants). Since new electrical equipment always comes with a properly sized in-line fuse, there isn't really any need. But once an owner knows what the electrical equipment will be and the proper fuse size, it is possible to go with just a breaker and eliminate the in-line fuse behind that switch.

I was surprised to see that the cost is basically the same as purchasing an inline fuse holder and a supply of fuses. The benefits would be two fewer electrical splices in each panel circuit and fewer fuses on board. It will require that my present radio in-line fuse (6A AGC glass tube type) be replaced with a 5A breaker, as the next size up in the Blue Seas series is 7A. The breakers aren't available in a slow-blow type, but I don't think any of my inline fuses are slow-blow, not even the wipers.

My boat came with a stash of random fuses, which made me a little suspicious. Then I looked in my own electrical kit and found a mess of styles and amperages of fuses going back to the old VW style. I probably only used one out of each package. Time to stop accumulating fuses.

Mark
 
Yes, the factory puts in one universal panel, because they don't rig the electronics. The dealer or owner does that.

Often there will be more than one circuit on the "instruments" switch--this might include the radios for some folks. Back to the examples I gave--and why each instrument will still have its "turn on". Just like "lights"--you don't want all of the cabin lights to come on. I leave the light over the galley, "on", and when I hit the "lights" switch, that is usually the light I want. I know that the 3rd switch down is the lights, in the dark.

The Blue Seas fuse blocks in the series I illustrated comes in 6 and 12 fuse types. For the 16 a single 6 may be enough.

Probably best, when you expand, to allow room for future owners to also expand, without re-wiring the boat. Often the factory wiring can be tidied up. I have seen poor crimps, and even crimps which did not make contact with the wire...In the past quality control was a bit lacking. It seems to be much better as of late.
 
Mark, I agree with what Bob says, in fact I have redone much of my wiring as I've added so much electronics. My original "switch board" broke as I was drilling into it to add a few more switches. So I ended up fabricating a new one, closely resembling that old one. The original switches and breakers are all there. Those would be the horn, nav & anchor lights, bilge pump, windshield wipers, and cabin lights. I've since added switches for my radar (as I don't want it constantly on every time the multi-function display is on), a second bilge pump, my NMEA 2000 network, and autopilot. For those switches, I bought the appropriate sized push button fuses that match the other original ones. Then I have a 12 place fuse panel on the berth side of the helm bulk head that has fuses for my antenna splitter, two GPSMAPS, two VHF's, berth fan, AIS transmitter, cockpit accessory plug, am/fm radio, spot light and a few others I can't remember. I also ran a much heavier 6 gauge battery wire from the battery to the fuse block. There is a shut off fuse located at the battery for that one. You can see photos of the fuse block and new switch panel in my Midnight Flyer album. (I think...) Colby
P.s. just looked, it's a few photos in the middle of the Autopilot Installation album.
 
Pulled all of my breakers and they aren't all just the stock 15A. It appears that the older style of breaker didn't have the amperage printed on the reset button. That makes it a little difficult, as you have to pull them to see what they are. Mine were between 3A and 10A, some circuits over fused and some under fused. By moving them around, all I need to buy is a 3A for the AFI wiper (it was on a 10A) and a 15A for my new bilge pump (it was under fused on a 6A, although the float switch was on a 7.5A in-line fuse).

So much for me assuming that the breakers were all the same.

Mark
 
Back
Top