DC Wiring - Neutral Wire

Richard19068 · Nov 8, 2018

Here is a relevant article from BoatUS which essentially gives the same advice as Dennis in reply 13 suggests.

http://www.boatus.com/boattech/articles/electrical-wiring-on-boats.asp

Scott T-Bird · Nov 8, 2018

If I'm pulling new wiring through confined areas, I often use a jacketed pair of wires so that there is more protection for the wiring. Thus, I usually have a separate negative for each positive. I do have exceptions. I use a common negative for the 3 circuits that run up the mast (anchor, steamer, deck lights). That way, I can use a plug with 4 pins at the mast base. The caveat is, if you use a common ground, be sure to size it correctly for the ultimate load. I have heavier gauge downstream than the individual negatives. Even so, I don't worry much because I don't often have more than 1 of those lights on at a time.
In general though, I suggest a separate negative for each positive.

Jacktar · Nov 8, 2018

Use a separate negative from the bus bar for each circuit, you don't want the entire nav .cabin , and mast lighting system to all go down because of one bad wire common to all the circuits.

Maine Sail · Nov 9, 2018

Bill,
Some very nice work! If more folks took the time to do the job as you did we'd have a hell of a lot less electrical related boat fires...

cagreen75 · Nov 12, 2018

120 volt AC (Alternating Curent) circuits use black as hot, white as neutral, green as ground or what is commonly know as the bond wire. If you do not use any of those colors for your DC (Direct Current) circuits you will not likely cross AC and DC circuits together. Although you do find Red wires in AC circuits in a house red wires to my knowledge are not used for AC circuits in boats. Our Catalina 30 uses all red wires for hot or power for all DC circuits in the boat. Black wires are used for DC ground wires. This presents a problem because black wires on the boat are also the AC hot wires. Connecting a DC ground to AC hot is disastrous for obvious reasons. So it makes sense to me that a yellow DC ground is the way to go. You may think that color coding all the circuits in your boat is helpful but in the end if you have to troubleshoot an electrical problem color coding does not always help. For example if your port navigation light was not working but your starboard light was then you would immediately check for a burned out bulb as both of the lights get power from the same source or switch. If the bulb is ok you would then probe the connections in the bulb socket for 12 vdc. If you find no voltage in the socket there are only two things that could be wrong. Power is not getting to the socket or there is no connection to dc ground. To check the ground you could do a continuity test from the from the outer socket of the port light to the outer socket of the starboard light socket. If you get continuity between them you have a power problem to the port socket or the socket itself is the problem. The thing to take away from this is that it does not make any difference what color the wire is in this case as you have not needed to know what the color of the wire is to determine the problem. In electrical troubleshooting this is often the case. The only time color coded wires makes any difference is when you use a single power source to power two things on one circuit. It may be helpful in the case the wire is broken or cut between the two devices. For an uncomplicated wiring system such as what you discribe it seems like a lot of trouble to use color coding. One thing that is not mentioned here is the subject of grounding both AC and DC. Grounding is especially important on the AC side as without out it there is a possibility that in the event of a shorted device in the boat the case of the device could become hot. If that were to happen and you touched the device and say the water faucet you would become the ground path for that device and possibly be electrocuted. Poor or no ground from the boat to the shore power can and does energize the water around your boat and also can and does electrocute people every year. One of the reasons marinas do not allow swimming at the docks.
I have to say that if you are unsure or not at least very knowledgeable about boat wiring you can probably save yourself a lot of quality sailing time and anguish about whether you have done the job correctly. If you still want to do the job and you are comfortable doing it I highly recommend following the advice of others on this thread and thoroughly read the publications that have been suggested here. Good luck.

Seaforme · Nov 12, 2018

Very good reply Maine Sail!

yachttapper · Nov 12, 2018

Be sure you conform to all ABYC standards for wiring. Wire crimp players, marine wire, support of wires, color coding, minimum wire size= 16 Ga, etc. An surveyor may find sub par wiring at her next survey. Just saying.

LeslieTroyer · Nov 21, 2018

JetLaggedChef said:
I've found this inexpensive one ($190 https://www.amazon.com/Tripp-Lite-A...d=1542837912&sr=8-5&keywords=charger+inverter )

My questions are:

1. What are your thoughts/suggestions for reasonably priced charger inverters with the above functionality
2. As a general rule, do the charger/inverters with AC plugs actually on them normally allow you to run a wire to another AC outlet instead? The info provided online is very vague.

Thanks!

1) that’s just an inverter not a charging inverter like you were talking about. It is not marine rated. I wouldn’t have it on the boat.
2) not until you get onto the very expensive inverter chargers go yo get external wiring

If you don’t ever plan on running the inverter without being connected to shore power, then don’t install one till you know how many amps you want.

You need a breaker panel for the AC including your charger so why not get one with at least two breakers + main and install an outlet or two where you want. Be sure and budget for a galvanic isolator and a ELCI breaker + a smart plug/receptacle for your install - first two items now ABYC requirements.

Les

dlochner · Nov 21, 2018

@JetLaggedChef you have a small boat with big boat desires.

When dealing with electrical systems the first step is to realistically assess your needs and electrical demand. And then build your system to meet those demands.

Start with how you intend to use your boat. Daysailing? Weekend cruising? Short term cruising? Long term cruising? Each of those will drive your choices and decisions. If you are only daysailing, your electrical needs will be minimal. If you plan on long term cruising, i.e., weeks, months, years, you'll need a bigger boat.

For what electrical devices do you need an inverter? How much power do those devices need? How big of a battery bank do you have or can install? Inverters are not that efficient and you will need a large bank to support all but the most modest of needs.

How will the batteries be charged? From shore power? An alternator on the engine? Solar? The small charging circuits on an outboard are designed to recharge the start battery, not to recharge a large house bank.

These are the kinds of questions to ask and answer first. The answers will guide your decisions.

jssailem · Nov 21, 2018

@JetLaggedChef as @dlochner identifys, correctly, it appears your looking for a solution without understanding the problem. You do not need to spend money on the project proposed. You may of course or you could spend a little time, as suggested, to clarify and plan out your need. This likely will lead you towards the @LeslieTroyer solution.

Power for tools while on the dock is nothing more than an extension cord to the dock power source. You can wire the boat with it’s own service and AC plugs, or you can go old school and attach to the dock power only as needed with a cord. Properly sized for the app load anticipated.

Choosing to wire your boat for AC power follow the guidance of Les.

With the boat wired you can add a “charger” to power up a couple of batteries. These will provide DC power to start your auxiliary engine and DC lights for navigation or reading a book in the cabin.

Looking at what you want to power and how long you want to power it will be the stuff Dave suggests. Building a power need list. Then you can design the battery system to meet your need not a wild guess from one of us sailors.

Just thoughts. That you can access along with your new found knowledge from Nigel.

Scott T-Bird · Nov 22, 2018

I'm guessing here, but I think you really don't need an inverter. What would you do with it? Is this your solution for creating an AC power circuit without really building the AC circuit? I can understand your desire for a charger. If that is the case, then I would build the AC circuit appropriately for connecting to shore power, and get a good charger. I don't know that you can use a charger/inverter to substitute for a proper AC circuit. Besides, the price you mention seems pretty cheap for a charger/inverter combination unit. They seem to be much more expensive. I get it that marinized products are often way over priced. But I wouldn't want to be the person who finds out there is a reason why the $1 K plus units are the way to go if you want such a device.