What does the minimum viable power distribution panel setup look like?

[PNW]

Preface: I made a couple of posts about the mess of wiring issues I found on this new boat, but I only had the energy to post in the intro thread I had made so it was hard to get precise feedback, thus it was rec'd to me to make narrower questions in the specific forum for that category. This is my first chance to do a proper post like that, as I have been spending all of my available time doing actual work on the boat when I had only energy for either working or writing about the issues I found.

What I've done so far: I was able to figure out most of the system interfaces just by doing logical breakdown physically of the lines going here and there, but the one thing that has me stumped is the power distribution panel (circuit breaker panel? DC panel?). I have spent a fair amount of time just removing the super old wires that were just dangling there from yesteryear, and removing the old cable management system which was obscuring everything useful from my view and hiding a lot of really messed up bits and bobs like bundles of ends shoved into wire nuts or entire lengths of cable with only duct tape for insulation/shielding. I had to remove the primary battery selector switch and battery cables and batteries, so now I am left with mostly current (no pun intended!) wiring that contains still-useful endpoints (i.e. temp guage, indicator light, engine room air blower, water pumps, bilge pumps, horn, etc) BUT no batteries or big thick cables or 1-2-both-off selector.
and I have the ~1 AWG wires coming into the helm area from the bow to send power to the windlass (and it is properly controlled and fused at the bow already so just assume two cables at the helm are the endpoint here) and these used to be hooked up to the battery selector switch, thus bringing power from the old start battery bank, which had been used as the 12v side of the power system, to the windlass allowing the old batteries to be used for starting, all the 12v components, and powering the windlass, but remember I no longer have those batts, cables, or switch hooked up because it was melted from corrosion resistance heat.

Project reqs: I want to use the 12v components on the boat that still work fine.
I am not using shore power.
I am also not using the genset or the inverter/charger.
I want the engine start batts isolated so that each engine alternator charges it's own start battery, 1 battery right next to each engine, this is already set up and working. These are well-maintained engines so no I don't care about a "cranking for a long time" backup plan at this time.
I just need to be able to install a 12v battery directly at the helm where the distribution panel is, and have that battery power everything that has a DC breaker and is wired correctly.

The problem: I don't understand what I'm looking at when I need to hook the panel up to the battery. I see the shunt and I believe that thicker cable coming off of it goes to the POS(+) side of the battery, but I just am not putting together the mental pieces necessary to understand the other side of the diagram the NEG(-) side. So far no matter which black ground looking cable I try hooking up to the (-) terminal, I can't get any of the breakers to work, and am not measuring voltage at any of the points where I know what is supposed to happen there. I know that I am missing some understanding of where else to look for voltage to track down this (-) end cable and finish hooking up this panel, but instead of sitting there with my multimeter trying to figure it out through process of elimination, I would like for someone to just explain to me what is going on with the wires, jumpers, bus bars, terminal strips, and whatever else exists at the backside of the panel! I have watched a bunch of videos and looked at tons of forum posts and examples of bad and good wiring but I still don't understand what is the most basic version of this that has multiple circuit breakers but is not just a huge bundle of untraceable wires in a loom. My only other option is to just keep disconnecting things until I have something so basic that it's the same as if I just started from scratch and put a new panel together.

What I want: A written explanation of the basic I/O of DC breakers in a panel, without the inclusion of the AC side or shore power or any other extraneous parts. Or a diagram of this MVP of a battery hooked directly up to a panel without a selector switch or involving the engines or house bank at all. Or a picture annotated showing what the foundational parts are in said MVP design.

I will include two photos but for the rear of the panel it's nearly impossible to photograph right now with how tight all the wires are...also the panel doesn't have a hinge or anything so it's kind of tough to tell how to get better access. I will try today to remove the screws from the panel edges to see if it is possible to take better photos and have space to move wires and see where they all go. But I would love to get things at least energized today so I can move on to the system stuff that requires 12v.

Thanks in advance anyone who read through it all, I really want to understand this instead of just making it work and moving on!

 

[O C Diver]

For the future, write in short sentences and enclose more pictures. It's very difficult to understand you with long run-on sentences.

To your situation: the battery for all your accessories needs to be located in the engine room.

A red wire 1/0 or 2/0 comes from the battery to the main breaker on the 12VDC panel. There needs to be a fuse or circuit breaker where the red wire connects to the battery.

A yellow or black wire of the same size, goes from the battery to the negative buss (where all the black wires are connected behind the circuit breaker panel).

If you accomplish the above, you should have power to all the 12VDC panel circuits.

I can't tell from the picture if the two vertical rows of circuit breakers are all 12 VDC or if there are any 120VAC breakers. Obviously, they need to remain isolated from each other. What are the green wires going to? Green wires are for the boat's bonding system or 120VAC ground. They must never be connected together!!! Some older electronics (12VDC) have chassis grounds that must not be connected to the 120VAC ground buss!!!

How you plan to charge that battery wasn't clear from your post.

I'm assuming that hiring a qualified marine electrician to do some of this for you, isn't in the budget?

Ted

 

[PNW]

Consider it an R&D boat. No the batteries do not "need to" be in any location because I'm trying to learn how this thing works not just get it to work, I'm not even off the dock yet.

This post is about a desire to understand a concept, in this case distribution and circuit breaking of 12v power on a boat. Imagine you're going to build a boat but didn't have the hull yet, and you just have your engine on a stand and hook it up to a Jerry can of gas and then you hook the starter up to a battery on the shop floor. That's what I'm trying to do here: get all the parts working and understand the architecture so I can modify it.

What you said about there being a "main breaker" is likely the concept piece I was missing, so thanks for that tip and I now know where to start on it today.

If I still have problems I'll come back more photo-heavy, is just damn hard to get a focal length under the helm cabinet there.

 

[Flatswing]

Consider it an R&D boat. No the batteries do not "need to" be in any location because I'm trying to learn how this thing works not just get it to work.

This post is about a desire to understand a concept, in this case distribution and circuit breaking of 12v power on a boat. That's what I'm trying to do here: get all the parts working and understand the architecture so I can modify it.

"A red wire 1/0 or 2/0 comes from the battery to the main breaker on the 12VDC panel. There needs to be a fuse or circuit breaker where the red wire connects to the battery.
A yellow or black wire of the same size, goes from the battery to the negative buss (where all the black wires are connected behind the circuit breaker panel).
If you accomplish the above, you should have power to all the 12VDC panel circuits."

As was just explained to you by OC Diver, this is the way almost every boat is wired for 12v systems. The engine starter/alternator is wired to the battery; large (high ampacity) B+ & B- cables connect that battery to the appropriate bus(es) near the dash/distribution panel. B+ should be red cables, B- will most likely still be black (Modern systems and new work now use yellow so as not to confuse with AC hot which is also black).
From that B+ bus should be a fairly large ampacity cable from the B+ bus to the line side of the 12v Breakers in the distribution panel. All the respective B- wires from various 12v devices congregate at the B- bus(es). Shunts are typically on the B- side. Since there is a limit to how many wires can connect to the load side of each breaker, more complicated boats usually have a second distribution panel (no fuse or breakers) more a series of terminal strips that allows multiple loads to be connected to each breaker line output.

Note that typically the B+ & B- for each engine's gauges (tach, volts, oil pressure and temperature) are carried separately in the wiring harness from the engine to the engine control panel(s) occasionally you will find some devices B+ connected to the ignition switch if present.

 

[Delta Riverat]

Yes, I see where the 1-2-all-off switch was. This is the start point. The 2 house battery positives are on 1 and 2 on the back of the switch. The common goes to the 2 buss bars you see on the 2 columns of breakers just below. Once you get that fixed the breakers should all work. Should is the operative word here -

 

[PNW]

It's not obvious where the main breaker is for the 12v section. In the uppermost panel there were 3 breakers labeled a single pole 1x"DC control" and the other two had two poles each 2x"shore power" and a 2x"generator". But I don't have shore power or a generator so all I'm looking for is a very standalone isolated setup so that I can move forward with cleaning, inspecting, and repairing/replacing other systems. Currently what I'm worried about is that I cannot move the boat around under its own power. I need to be able to run the engines, shift into gear, and be able to add/subtract 12v components as I run tests throughout the summer.
I see what you're saying and clearly I need to sit down with the Nigel Calder books and a pen & paper and really make sure I know what the architecture design is and what each piece means.
Thanks everyone for the guidance; I'll slow down, say less, practice multimeter more.
Cheers

 

[PNW]

Sorry it's been a long day. The point of saying I found those 3 breakers is that they do LOOK LIKE main breakers but the DC control one was not wired up to anything. The other two I specifically am isolating because I'm not using those methods of power generation.

 

[Delta Riverat]

My boat doesn't have a DC main breaker. It does have a main 400A fuse which is down in the engine room. It will have fuses on all the house batteries before the selector switch. The DC circuits are all protected by the branch breakers. You could add a main breaker to your panel also but that would be a long way from the batteries.

 

[PNW]

I did also manage to finally get a good picture of the bottom row which was another 115V AC? Panel. The labels indicate that these breakers controlled the AC side of the inverter output? I guess?

Going home now to read the manual again and make some crude sketches.

 

[PNW]

My boat doesn't have a DC main breaker. It does have a main 400A fuse. It will have fuses on all the house batteries before the selector switch. The DC circuits are all protected by the branch breakers. You could add a main breaker to your panel also but that would be a long way from the batteries.

I don't have any house batteries yet but I will keep this in mind, thanks

 

[CharlieO.]

I don't have a breaker for the dc panel, my panel is fed from the 1/2/both/ off switch

 

[Delta Riverat]

Yup, same as mine.

 

[O C Diver]

I did also manage to finally get a good picture of the bottom row which was another 115V AC? Panel. The labels indicate that these breakers controlled the AC side of the inverter output? I guess?
View attachment 155828
Going home now to read the manual again and make some crude sketches.

One of the things to understand about boat electrical wiring is that amps are amps regardless of voltage. As a result, 120 VAC breakers are often the same breakers used on the 12 VDC circuits. The ones on my Paneltronics panel are all the same model just different amperages. So it's really important to verify which voltage section you're on.

The other challenge to older boats is wire color. Most older boats used red (positive [+]) and black (negative [-]) for DC wiring. In addition, AC wiring is black (hot), white (neutral) and green (ground). The boat's bonding system is also green to help confuse things.

Newer boats have yellow as the negative (-) for DC wiring. So you will likely have a mix of old and new. Double check every circuit with a black or green wire. Wire color mistakes can make for impressive failures!

Ted

 

[Bmarler]

I did also manage to finally get a good picture of the bottom row which was another 115V AC? Panel. The labels indicate that these breakers controlled the AC side of the inverter output? I guess?
View attachment 155828
Going home now to read the manual again and make some crude sketches.

Many times the ac panel would be split so that the inverter would power only a few specific circuits.

 

[Bmarler]

If you just want to power up the panel you can bring a battery to it and put wires to the buss.
Be sure that there’s a fuse on that wire.
All of the breakers should be connected to the dc positive buss. That buss should have a place to attach the power feed from the battery/battery switch.
There should also be a dc negative buss nearby to connect the negative terminal of the battery.
Keep in mind though, you need to be sure there are no other cables on the positive buss that aren’t accounted for. You don’t want to energize a loose ended wire.

 

[PNW]

Yeah that all checks out, lots of green and black wires from each past decade stashed and stacked and half of them ending up adrift wires.
I'm not using any of the breakers from the two panels that say AC on them. I guess now the metal bars going between all the DC breakers is the positive bus, but was wondering why some have piggybacked wires coming off it, now what you're saying makes sense because someone just wanted power without taking more time so they just attached it to the nearest positive and negative bus bars. I had tried to hook a battery up as your described but the multimeter readings just didn't make sense to me, but I think I had the flow backwards mentally. I'll return today after some coffee and take my notebook along and label more wires as I remove them. Thanks for all your help everyone.

 

[Bmarler]

Yeah that all checks out, lots of green and black wires from each past decade stashed and stacked and half of them ending up adrift wires.
I'm not using any of the breakers from the two panels that say AC on them. I guess now the metal bars going between all the DC breakers is the positive bus, but was wondering why some have piggybacked wires coming off it, now what you're saying makes sense because someone just wanted power without taking more time so they just attached it to the nearest positive and negative bus bars. I had tried to hook a battery up as your described but the multimeter readings just didn't make sense to me, but I think I had the flow backwards mentally. I'll return today after some coffee and take my notebook along and label more wires as I remove them. Thanks for all your help everyone.

If there are wires hooked directly to the positive buss they were likely added by previous owners. If the builder didn’t build the panel with expansion capability you have to get creative.
Some will just wire to the buss and fuse the individual device instead of adding a sub panel and breakers.

 

[O C Diver]

I had tried to hook a battery up as your described but the multimeter readings just didn't make sense to me, but I think I had the flow backwards mentally.

A recommendation would be to turn all the breakers off including the main, and the check for resistance with a multi meter before hooking up the battery. After confirming no resistance, turn on the main breaker you may see some resistance if there is a volt meter.

Before hooking up the battery, turn the main breaker off. Then hook up the battery. Then turn on the main breaker. You should see voltage if there is a volt meter. Then go one by one through the breakers to prove out each circuit.

Ted

 

[wkearney99]

With electrical problems there's a fine line between figuring out what's wrong, and just doing a rip-and-replace. It can take HOURS (if not DAYS) to troubleshoot electrical circuits. Sometimes it's faster and less expensive (long term) to take steps closer toward 'starting over'.

Your killers with old wiring are unknown connection distribution points and corrosion (and often a combination of the two). One challenge is narrowing down all of the places where wires are being connected to a distribution bar. Next is checking that you're not losing too much voltage between them and their battery source.

Wire loses voltage over distance. Larger gauge (thicker) wire loses less. You can measure this with a simple volt meter. While there's an active load on the wire the voltage at points along the way will drop. More than about .2 volts can be a problem. Corrosion, loose connections and undersized wire for the load can all contribute to voltage loss.

This is a pretty good video that discusses it:

If you're thinking about continuing to use existing wires at least be sure they're up to delivering the load you plan on putting through them. TEST THEM. This includes both the positive AND the negative wiring. The current has to circle back to the battery, and sometimes people neglect to check that their negative wiring is in good working order.

 

[wkearney99]

Meanwhile take pictures and PUT LABELS ON EVERYTHING. Videos can help too, as it might cover things that get missed in still pictures.

You don't have to get all fancy with heatshrink and label makers, though those are nice long-term. Blue painters tape won't stick forever but it's good enough during troubleshooting. Know that tape WILL get pulled off of wires if you pull things around them. So more permanent/secured markings are helpful. Black and a silver Sharpie markers are also handy for scribbling something useful on the cable insulation.

And if you find need to remove/add wires through tight spots understand that they can get entangle/braided and that movement of them against other wires can cause damage to the insulation on them. Especially if there's a connector left on the end. You don't want to have something pulling past good wires causing damage to them. If you can't feed the wires through easily then it may require a different plan.

 

[PNW]

Thanks Bill, great tips.

I am already regretting now that I didn't just pay the thousand bucks for a new cable initially, but I had ambitions for finding a way to run it shorter because it didn't make sense to me how they ran it. That's when I started testing my understanding and once I realized I was wrong I had already taken too much stuff out to go back.

New goal is to just finish my task now of understanding power distribution concepts, re-tip the base systems wires with good ends, label as many as I can, and take notes along the way.

I'm not worried about figuring it out I'm just bummed to disappoint the wife by missing my goal deadline.

 

[PNW]

I also did find the original wiring diagram but I'm seeing exactly as mentioned earlier that many patches have been baid-aided on top of what's drawn. Looks neat though.

 

[Delta Riverat]

About missing your goal...

That's what causes big problems, a schedule and a rush. You did the right thing. Better to do it right and be sure than to rush and don't know.

Better that your boat not running and tied up secure then to have it out with a problem and now securely piled up on some rocks.

 

[wkearney99]

Thanks Bill, great tips.
View attachment 155849
I am already regretting now that I didn't just pay the thousand bucks for a new cable initially, but I had ambitions for finding a way to run it shorter because it didn't make sense to me how they ran it. That's when I started testing my understanding and once I realized I was wrong I had already taken too much stuff out to go back.

New goal is to just finish my task now of understanding power distribution concepts, re-tip the base systems wires with good ends, label as many as I can, and take notes along the way.

I'm not worried about figuring it out I'm just bummed to disappoint the wife by missing my goal deadline.

With boats and planes you never want to have artificial deadlines. You get there when you get there. Remember that when land schedules start making you think you should rush things on the water. Wind, waves and water do not care about when you "need to be somewhere".

As to that picture, YIKES. That's a prime example of corrosion. No doubt that wire can no longer pass it's rated load. I'd be extremely skeptical of it's long-term resistance against more corrosion. I'd prefer seeing closed-end terminals not that open-end style. And proper heat shrink. The problem is for larger gauges of wire you need to have some pretty heavy duty cable crimping tools in order to make a tight fit. For the wires carrying high current I'm inclined to have them made to order rather than struggle to make them on my own.

 

[Docktopus]

Thanks for all this information, I don’t have much to add, but I learn a lot from this discussion.

My only addition is, if you are into podcasts, listen to Cautionary Tales episode “Danger: Rocks Ahead”. It is all about the problem of having a plan while under way.