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Discussion Starter · #1 · (Edited)
Rewiring my 1977 Santana 28 - fuses, charging, buss bars... oh my!

I've been doing a bunch of reading and figured I'd begin some documenting and Q&A as I rewire my 1977 Santana 28.

Pictures is the back of the main panel with 1-2-B switch and cabin/ nav switches. I didn't get a before pic, but this is after removing about 25lbs of wire left behind from past PO projects

ImageUploadedByTapatalk1396352926.363930.jpg

I think maybe a buss bar or two, and some fuses are in order? Only fuse I found in the entire boat was inline on the old solar panel line direct wired to one battery.

My questions to get this started:

For the Cabin and Lighting shown, can I fuse this with a single fuse in the common line to the switches? Switches cover: Cabin Lights and Fresh Water Pump, Running Lights, Spreader Light (Led), Anchor Light (LED), Steaming Light.

Ground - existing all went to that long thin mounting screw you see bottom left of the pic, with a ground wire straight to the engine (diesel Westerbeke). I plan to setup a buss bar for ground, should that go to the battery ground, engine, or both?

For additional power (radio, GPS, etc), should those each be individually fused, and run off the common pole from the 1/2/B switch? I've seen a few different options documented in my reading.

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If you can edit the subject title you might get a better response. Theres some great whiz kids on this forum but they dont have time to read every thread and may better find your question.


Mark
 

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You need to size fuses to cover the wire on each circuit. You should have a fuse (or circuit breaker) per circuit. I would expect the cabin lights and freshwater pump circuit to use larger gauge wire and require a larger amperage fuse than the other circuits. You can't count on a single battery fuse to cover the entire boat, because it would be oversized for any individual circuit. You should have a battery fuse in addition to per-circuit fuses.

Individual fuses and switches give you increased flexibility and protection. You should decide what can share a circuit and what can't. On my boat I have nav electronics on one circuit and VHF on another, but they could potentially go together since they are generally used together. I personally wouldn't put cabin lights and freshwater pump on the same circuit, they aren't used at the same times and have different failure modes.

There are some good marine electrical books available which will help you out. They are a minor cost compared to the wire, circuit breakers, and fuses that you'll be buying.
 

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Further to Alex W:

Your criteria for a branch circuit (that is, the wires that go to each load.)
  1. Load distribution. Just like in your house where most branch circuits are 15 amp the idea is to use lots of low current carrying circuits so you don't have to run big wires around the entire boat. Just like in your house you may have a couple of special circuits - 30 amp and 50 amp in homes for air conditioners and electric dryers are not uncommon.
  2. Overload protection - that is to be able to turn off a circuit if something goes wrong.
  3. Isolation - to make sure that one bad load does not bring down the entire system.
  4. Switching - many people use the circuit breakers as the "on/off" switches for various circuits - e.g. navigation lights.

In your planning of individual branch circuits isolation is the key. Keep in mind that if something on a branch circuit fails you lose the entire branch. So if you designed a circuit that had both your navigation lights and your depth instrument you would lose both if one failed. Navigation lights are more prone to failure - they are out in the wind and wet. So by lumping them with the navigation lights you are increasing the likelihood that you will lose your depth sounder over the alternative of having them on a different branch circuit.

Take a look at the Traditional Metal Panels - Blue Sea Systems panels. They have labels that will give you an idea of how most boat builders set up power distribution.

If you are going to rewire the boat put in all the wires both AC and DC that you might want to add in the future. What you will give up in cost of wire you will make up in future hassles if you decide you want to upgrade.

One final thought - you have a 37 year old boat. If you intend to sell it anytime soon remember that you will only get 10% to 20% of the cost of the materials (not your labor) in the selling price of the boat. So don't go overboard with costly upgrades.

Fair winds and following seas.
 

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Discussion Starter · #6 ·
Thank you both for your thoughts and info on this.

I hadn't thought much about the AC side. We do have shore power to 3 GFI outlets in the boat. Used primarily to run fans and lights at the dock. But no fuses anywhere in that system either.

I like the idea of using breakers for the switches as it fills both needs. I will do some digging into the products listed and update as I proceed.

One follow on question: I have a Group 27 and a Group 24 Battery. Am I best off using the 27 for house and 24 for reserve/ start or vice versa?

Tom
 

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Re: Rewiring my 1977 Santana 28 - fuses, charging, buss bars... oh my!

I've been doing a bunch of reading and figured I'd begin some documenting and Q&A as I rewire my 1977 Santana 28.

Pictures is the back of the main panel with 1-2-B switch and cabin/ nav switches. I didn't get a before pic, but this is after removing about 25lbs of wire left behind from past PO projects

View attachment 25970

I think maybe a buss bar or two, and some fuses are in order? Only fuse I found in the entire boat was inline on the old solar panel line direct wired to one battery.

My questions to get this started:

For the Cabin and Lighting shown, can I fuse this with a single fuse in the common line to the switches? Switches cover: Cabin Lights and Fresh Water Pump, Running Lights, Spreader Light (Led), Anchor Light (LED), Steaming Light.

Ground - existing all went to that long thin mounting screw you see bottom left of the pic, with a ground wire straight to the engine (diesel Westerbeke). I plan to setup a buss bar for ground, should that go to the battery ground, engine, or both?

For additional power (radio, GPS, etc), should those each be individually fused, and run off the common pole from the 1/2/B switch? I've seen a few different options documented in my reading.

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Those "switches" look like breakers to me. If they are, and if they are rated properly - 15 amps or less for 14 gauge wire - that is sufficient for the hot side. A picture of the front would confirm this.

All negatives are common. The negatives of each battery should be connected at a bus and from there to the engine block with a single wire the same gauge as the positive wires. From the bus one wire the size as the small wire to the switches or breakers to a smaller bus near the panel with each load's negative fed from there.
 

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Assuming that the condition of the batteries is equal the 24 for starting and the 27 for house loads.
 

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Discussion Starter · #9 ·
Re: Rewiring my 1977 Santana 28 - fuses, charging, buss bars... oh my!

ImageUploadedByTapatalk1396440348.452085.jpg

ImageUploadedByTapatalk1396440369.735618.jpg

Attached is pic of the switches which appear pretty old. Appreciate guidance on whether they may be/ have breakers.

Also, on topic off in fusing, In the attached schematic, trying to determine if I need breakers between battery isolator and 1/2/B switch if I am using terminal fuses at both batteries. Or if there's a better config in this case for fuses.

Also, how/ where and should I fuse the wire from common in 1/2/B to Starter?


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Discussion Starter · #10 ·
Re: Rewiring my 1977 Santana 28 - fuses, charging, buss bars... oh my!

Ok, did more Googling and sound that these are in fact breakers all rated 20 amp. I'm running primarily 14ga wire with some 16ga for cabin lights. It seems this *should* be ok, but wondering where I may have any risk at 20 vs say 5-10 amps that I see a lot of reference to in the forums.


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Breakers loaded on Blue Seas panels are 15 amp. 16 gauge wire is used most commonly. 16 gauge wire has an ampacity of 25 amps outside engine spaces so the 20 amp breakers are ok. The breaker is there to protect the wire. If you add any wiring use 14 gauge wire, it's a better choice for voltage drop.

Do you have the isolator in the schematic? If so get rid of it and get an Echo Charge instead. There is a voltage drop through the isolator and the batteries will take a lot longer to be charged. The Echo Charge has no such issues. It does change the wiring from the alternator - for the better. The alternator output goes direct to the house bank. The Echo Charge is wired between the batteries positive posts. This changes the switch to a use switch with no effect on charging - charging both batteries will be totally automatic regardless of switch position.The Echo Charge comes with a fuse for each positive wire so breakers are not needed.
 
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