DC Distribution Panel Rehab

[Foswick]

I looked behind the DC distribution panel, for the first time, the other day. Found out it was originally wired by H.P. Lovecraft:

I am going to replace the panel, but not this year. I am designing a replacement panel, but likely won't finish it any time soon. Just one of those things that will never make it to the top of my list.

In the meantime, I want to do some tidying.

To my mind, the panel should have short wires leading to one or more connectors that, in turn, connect to one terminal block for each circuit. That way, I can remove the panel cleanly by disconnecting those connectors. And, I can access any of those circuits by their terminal block, without doing any wire splicing. This eliminates all of the spaghetti.

What I don't know is what connectors and terminal blocks to use. I am thinking of something like Deutsch DTP 4-pin connectors to connect every four circuits to four separate terminal blocks. Those are 25-amp connectors, and I don't think any existing circuits exceed that. (I'm not on the boat right now.) I also like Anderson Powerpole connectors, but they are a bit bulky and more vulnerable to the elements.

As for terminal blocks, I don't know. What the boat currently has is a mash-up of awkward splices and both positive and ground bus bars - mostly uncovered. What I want is:

• Easy to add/remove load devices/circuits to each terminal block. (I like screw terminals. Spring-loaded terminals are even nicer, but I don't know that I've ever seen them except for very low-current loads.)
• Corrosion resistant
• Relatively compact, since I will need about 12. (Currently, the DC panel only supports 8 circuits, but I want to expand to at least 10.)
• No exposed positive contacts (like an uncovered bus bar)

Recommendations?

If my goal isn't clear, I'll provide a schematic, but I think it's pretty straightforward, even if I'm not explaining it well.

 

[mermike]

Yep, that's ugly. I would be concerned about inserting any additional connectors into the circuits. Each connector adds resistance and voltage drop, How often will you need to remove the panel, and why? If you still want the panel to be detachable, terminal strips with heat shrink fork terminals will work. Label everything!

 

[Foswick]

Yep, that's ugly.

I'm afraid I'm going to turn to stone every time I look at it.

I would be concerned about inserting any additional connectors into the circuits. Each connector adds resistance and voltage drop,

Yeah, but at such low current, we are talking about millivolts - probably not measurable on my multimeter and well within the tolerance of anything I have attached to that circuit.

Label everything!

That's one thing that drive me nuts about that mess. A bunch of that wiring is actually labelled with a modern label maker, which means that someone, at some point "upgraded" that wiring? I mean, it is original wiring, for the most part, but someone got in there and decided, "Oh, I'll put some labels on these wires and shove them back in there." I'm glad they did label, but couldn't they have at least brought some order to it? It couldn't have been trivial to figure out what everything went to, so why not take another couple of hours to do it right?

<sigh>

OK ... breathe ...

Point well taken about the optionality of connectors between the panel and the terminal blocks. I don't really need to remove the panel except probably once when I replace it. I might do just as well to wire directly to the terminal blocks. Slightly simpler.

 

[TrapperJohn]

I can see why you're concerned and I think I understand what you're trying to do.

CAVEAT: I've not had to rewire a marine breaker panel yet (it's in my future plans), but I have had 30 years of experience in industrial instrument and control wiring in some very hostile environments.

I'd be concerned about the 4-circuit plugs in addition to the terminal strips. It just adds another point for corrosion to add resistance to the line 10 years from now.

If it were me, I'd make sure the field cables are good, them re-terminate with a good quality ring terminal to the terminal strips. From the terminal strips, I'd go strait to the breaker panel with one size larger wire from the terminal strip leaving enough to pull the panel off for inspection as your current picture shows. You can tie the wires together by rows of breakers so you don't have them all twisted around each other. Then when you need to pull the panel again, you can do it by groups and they stay as one unit. I would avoid spring-loaded connections. Over time, those springs could become corroded or weakened by fatigue possibly adding resistance to the circuit.

If you you did use the plugs, I would again go with the higher rated wire/plugs between the field terminal strips and the panel, apply some dielectric grease to the plug connections and then seal the plug together with tape or adhesive shrink tubing. You may want to group your field wiring to the terminal strips by wire size; e.g., all the 14 ga wire to one strip, 16 ga to another etc. That simplifies your plug selection.

Label everything as you go.

For me, the end goal would be that the breaker panel end be the least likely cause of voltage drop or overheated connections. That leaves you with just the field wiring to the terminal strip.

That's just my humble opinion. Take it for what it's worth.

Oh, and it you're installing terminal strips, buy extra screws and keep them as spares for the inevitable (for me) dropped screw. Maybe this only happens to me.

 

[sailcapt340]

I don’t have a lot of photos of behind my panel for you to see.. But I was in there just recently to connect a new power cable to a new VHF I just installed.
Prior to that I haven’t been “in there” for years. Once to replace a fuse for the utility plug. No real need to open it up aside from replacing a faulty breaker.

To my mind, the panel should have short wires leading to one or more connectors

What I can tell you is, mine has short wires as you mentioned.
When I remove the screws holding the panel on, the panel will drop down and forward about 1 inch and that’s it. Making it very difficult to access the lower breakers in the line.
So use caution if you choose to shorten your wiring, plan for future openings to get in there.
Mine is a 2000 Hunter 340, prior to that, the earlier year Hunters had a panel with a piano hinge mounted on the bottom. You simply had to remove 5 screws and fold the panel down to work on it. Great idea! What ever happened to that? I did try to add the same piano hinge design to mine years ago, but the wires were “too” short to allow it. Again, use caution in your ultimate goal.

While mine, compared to yours, is neater looking, it is still a birds nest of wiring to say the least. But when you do get into this project, you should be able to isolate each breaker, one by one, add your new connectors and neaten up the wiring. Time and patience, nice off season project.
So this was really just a couple of ideas for you to consider going forward and an opportunity to see behind another panel as a comparison. Can’t hurt to look, as there may not be a lot of photos of this particular area.

buy extra screws and keep them as spares for the inevitable (for me) dropped screw. Maybe this only happens to me.

No it isn’t just you…. definitely take these words of wisdom!

In my case, the VHF breaker is the 5th one down. Again, given the short wiring, there are 2 screws down in there somewhere??
The string you see is a pull I placed to pull the new power cable through once the radio was mounted. It was 5 feet from the breaker to the radio and in the back of a 4 foot deep hanging closet. No easy access at all.
Hope this helps you somehow but at a minimum you have some visuals.

 

[Foswick]

So use caution if you choose to shorten your wiring, plan for future openings to get in there.

My current "plan" is to allow enough to pull the panel about about 6-12 inches, but that was my reasoning for having the panel go straight to connectors - so I can just unplug it and set it aside. But, as Mike rightly pointed out, that might be unnecessary complexity for the occasion once every few years when this might be a little bit more convenient, but still unnecessary.

... nice off season project.

That would be the sensible thing to do. But now that I know that is back there, I can hear its sinister whispers at night, keeping me awake.

But ... yeah ...

Like I said, I am designing a new custom panel. So, maybe I should just finish that and do everything at once.

 

[mermike]

The Curse of the Dropped Screw is why I use flanged fork terminals for connecting to a terminal strip, instead of ring terminals.