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DC Wiring - Neutral Wire

Jul 9, 2018
65
Catalina 25 Lake Monroe
I've just purchased a 1983 Catalina 25 with only basic electric systems (only cabin lights and navigation lights). It doesn't currently have a depth finder, etc.

The previous owner did an immaculate job restoring most of the boat, except for the wiring. The wiring technically works, but there's a billion splices that aren't up to snuff, with wires that are spliced and change colors once or twice down the line.

I've diagrammed all the current wiring and am planning to rewire the boat since it's all currently accessible. I found the attached chart which identifies the appropriate color to use for each system, which I intend to follow. I find life is much simpler when I can look at a wire any point along the way and determine what the wire is for.

In the chart, there's only a listing for one black (or yellow) wire for the neutral return. I'm purely doing DC wiring.

The question is... is it normal to use a single black neutral wire for all the systems that's spliced together where necessary? Or would you use a separate black neutral wire for each system and somehow color code it (for example, add dark blue nail polish marks every 12" so you know which system the neutral belongs to)?
 

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Jan 19, 2010
8,272
Hunter 26 Charleston
I think the best way would be to create a neutral busbar

Something like this



And direct all of your neutrals to this one busbar. Then make sure the busbar is very well grounded with a 9 or 10 gauge wire to ground.
 
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Feb 6, 1998
11,228
Canadian Sailcraft 36T Casco Bay, ME
DC does not use a neutral as terminology it is referred to a negative conductor. 120V AC would have a HOT and NEUTRAL and DC has a POSITIVE & NEGATIVE.

For most DC circuit wiring, other than those listed, it will be red for positive conductors and black or optionally yellow for DC negative. If starting from scratch, and I would advise simply gutting the existing wiring and starting from scratch, it would never be a bad idea to use yellow for DC negative. Most new boats are wired using yellw for DC negative to avoid confusion. This way if you ever were to add AC then there is no confusion between AC Hot and DC negative.

I would strongly urge you to purchase a book such as Charlie Wings Boatowner's Illustrated Electrical Handbook - Second Edition and digest & comprehend it thoroughly before starting. 55% of boat fires are electrical in nature with DC being a huge portion of this..

There is a lot more to marine DC wiring than just choosing wiring color. Charlie's book follows the applicable ABYC standards better than most and is pretty simple to grasp.
 
Jun 8, 2004
8,099
-na -NA Anywhere USA
I had a costumer who had purchased a used boat from a dealer in another state years ago who installed a second battery for a two battery system with all black cables. Thankfully she was wearing glasses as one battery blew up in her face.

AC hot and DC negative are both black. There have been many other incidents due to this confusion. Dealers to include myself demanded an industry wide change for color coding on new boats. The color yellow was adopted for DC negative which dramatically cut down these types of incidents.

Therefore gut all the old wiring and start new using yellow for DC NEGATIVE ONLY
 
Jul 9, 2018
65
Catalina 25 Lake Monroe
Thank you for the advice on the yellow negative and correct terminology. That's really great advice. I've also ordered the book and will read through it as well.

The panel on the boat has a bus-bar for the negative lines which is where I plan to put them. I was thinking more along the lines of does each system need it's own negative wire (since they're all being attached to the same bus-bar) or can they share an appropriately gauged negative wire.

My goal is to be able to easily identify a wire anywhere in the system without having to trace it. The boat is currently empty and it still took about 2 1/2 hours to follow and map all the current wiring. It would be much more difficult to troubleshoot in the future if I have to follow wires to guess where they go when the boat is loaded with other things. Color coding wires correctly solves this problem, but if I have multiple systems with multiple neutrals that are all yellow, I would have to mark the yellow wires to know which system that particular negative belonged to.
 
Jan 11, 2014
5,605
Sabre 362 113 Fair Haven, NY
y goal is to be able to easily identify a wire anywhere in the system without having to trace it.
Label each end of the wire. An easy way to do this is with write-on heat shrink tubing. The link is to Amazon, I've also found it at Lowe's and Home Despot.

Also follow the ABYC color coding. If you are really obsessive you could add labels in the middle of the run.
 
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capta

.
Jun 4, 2009
3,737
Pearson 530 Admiralty Bay, Bequia SVG
If I were building a boat, each positive wire for each use would be a different color. That way, anywhere on the boat you saw a blue/purple, for example, you would immediately know it was the mast head anchor light. I think the hardest part of this is finding tinned boat cable in a variety of colors.
 
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Jul 7, 2004
6,642
Hunter 30T Cheney, KS
Main has some good electrical advice on his site. I bought my crimper from him. Crimpers that work on 'regular' crimps do not work well on crimps with heat shrink sleaves on them.
 
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Jan 11, 2014
5,605
Sabre 362 113 Fair Haven, NY
Like these. These also work well on DC positive in case you don't use several different colors.
I started using the number approach, but then I would forget what the numbers meant. This was especially an issue on the battery terminal, is red #3 the Smart Guage sense wire? Or is it the Regulator sense wire? or the Battery monitor sense wire? :doh:

I found it much easier and quicker to use real word labels. At first I used a label maker and then covered the label with clear heat shrink. But I was always overheating the heat shrink which caused the label to turn black. Now I use the write on heat shrink unless I forget to put it on before putting on the terminal end, then out comes the sharpie.
 
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Jul 7, 2004
6,642
Hunter 30T Cheney, KS
One of my projects for the upcoming off season is to remove the daisy chained negative cables on my 3 batteries, charger and nearby distribution panel to a common buss bar beside the batteries. I'm not liking the stacked connections on the battery posts.
 
Jun 4, 2004
388
Hunter 23.5 and 25 Stockton State Park Marina; MO
Always use a separate negative wire for each circuit. Only exception is for multiple like items on a circuit such as cabin lights for example; with 1 positive and one negative coming from the switch panel bus and connecting to each light via a parallel spur. The main wires must be sized to carry the load of all lights on the circuit.
Dennis
 
Mar 6, 2008
519
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
The best answer I can provide for homerun negative or common side of circuits is to provide separate ones when it is in a circuit that draws high current. When there are several devices that take high current the voltage available at the device will be less as wire will act as a resistor. For such devices as motors, bilge pumps, auto helm use separate wires. Use nickle plated stranded wires only including the spades. Connect one circuit at a time, test then move to the next circuit. For labling, I use white plastic 2"X2" make notes with permanent marker and tywrap to the wire.
 
Last edited:
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Feb 6, 1998
11,228
Canadian Sailcraft 36T Casco Bay, ME
At first I used a label maker and then covered the label with clear heat shrink. But I was always overheating the heat shrink which caused the label to turn black.
You're most likely just using the wrong tape. When using a Brother P-Touch you want to use the TZe tape. If you're burning TZe tape you're simply applying too much heat or using a blow torch.

Wire Labeling (LINK)
 
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Jan 11, 2014
5,605
Sabre 362 113 Fair Haven, NY
You're most likely just using the wrong tape. When using a Brother P-Touch you want to use the TZe tape. If you're burning TZe tape you're simply applying too much heat or using a blow torch.

Wire Labeling (LINK)
I'll have to check the tape. The phase change goes quickly, everything is good and then it starts turning color. It is still legible, but looks worse than my poor handwriting. I use a heat gun, usually on a lower setting.
 
Jun 8, 2004
8,099
-na -NA Anywhere USA
When it came to labeling wires for example all red or black, some folks don’t bother to look at stickers and there are times stickers come off. I will disagree with anyone otherwise. Why? I use to be an insurance investigator and handled cases wherein incorrect wiring cost injuries and sometimes death in the mines leading to huge awards.
While as a dealer, I was able to speak privately to the adjusters about boat claims and was told about cases for the above due to improper color coding to AC and DC systems that most of you never hear about.
I strongly suggest proper color coding of wires and then label each wire as to what it is
 
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Jul 1, 2010
728
Seaward 25, Catalina 350 Erie, Pa
The question is... is it normal to use a single black neutral wire for all the systems that's spliced together where necessary? Or would you use a separate black neutral wire for each system and somehow color code it (for example, add dark blue nail polish marks every 12" so you know which system the neutral belongs to)?
In addition to what has already been said, in most cases you would be using duplex marine grade wire for runs through the boat, so no confusion among grounds. A particular circuit's ground is grouped with its hot wire inside the insulation jacket for the wire. Label at the ends. If you're thinking like automotive dc wiring, not like that at all.
 
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Feb 26, 2004
21,073
Catalina 34 224 Maple Bay, BC, Canada
I've also ordered the book and will read through it as well.

The panel on the boat has a bus-bar for the negative lines which is where I plan to put them. I was thinking more along the lines of does each system need it's own negative wire (since they're all being attached to the same bus-bar) or can they share an appropriately gauged negative wire.
Wait for the book, read it, then decide.

The three words I try to avoid: never, ever, always.

I minimize offered advice if they start with any of those three.

You should also get the Catalina 25 manual, which has a GASP! wiring diagram in it. Get it from the helpful skippers at the C25 Association website:

http://catalina-capri-25s.org/forum/default.asp?CAT_ID=1

Good luck, none of us was born an electrician. You can do it! :)
 
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Jun 8, 2004
8,099
-na -NA Anywhere USA
The old style Catalina 25 which I use to sell as a dealer too used the basic red (+) and black (-) for DC wiring. Suggest switch to yellow for black for today’s proper coding.