Wiring A Boat 101

Bamby

New member
If you have training or experience in electricity and electrical circuits;
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I am only going to very briefly cover the basics of the electrical standards found in the US Federal Regulations and ABYC Standards here. Contact ABYC and the Coast Guard to get the standards for Electrical systems. Canadian, ISO, and Australian standards are very similar. Go to Ike's List
In any case you should have books on marine electrical systems, My Book Store on Amazon.com , and get a copy of ABYC Electrical Systems E-11 .
Also ABYC has available U. S. Coast Guard Compliance Guidelines: Electrical Compliance Guideline.
The following are not verbatim from the regulations. It is my own wording. Print a copy and read the regulation!
First a note about the reasons behind the fuel, electrical and ventilation standards. Why is all this stuff necessary


The Federal electrical system standards apply to
Boats with permanently installed inboard gasoline engines for:
Propulsion
Generators
Auxiliary Equipment
This does not apply to:
Outboards:
Portable Equipment
Having said that, that is, the electrical system regulations don't apply to outboard powered boats, this is only in the Federal Regulations. The industry follows the ABYC standards, which are tougher than the Federal standards. ABYC electrical system standards apply to outboard powered boats, diesel powered boats and inboard gas powered boats. If you ever have to go to court, that's what the complainants attorney will ask you. "Do you meet ABYC standards"? So follow the ABYC electrical standards, even if you're making an outboard powered boat.
Canadian, ISO and RCD standards are very similar. See Ike's List. But follow the standard that applies in the country where you build your boats.


BATTERIES:
Each battery must be installed so that metallic objects cannot come into contact with positive terminals. (Or the negative terminal if you use a negative ground.) How can this be accomplished?
Battery Boxes
Boots on the positive terminal.
A cover over the terminals.
Use your imagination. There are other ways. The whole point is that you do not want a wrench or screwdriver of something metal that falls on the battery (like a metal portable gas tank) to come in contact with the positive terminal. This could cause a large arc and possibly a fire or explosion. It is best avoided.



Hydrogen gas discharged by a battery during charging must not be trapped in the boat, but free to make it's way out of the compartment to the atmosphere. Hydrogen gas is extremely flammable. The slightest spark will set off an explosion. So the obvious solution is to vent it from the boat. Make sure the battery compartment is ventilated. If you put the battery in a box, make sure the box is vented and the gas has a way to escape from the compartment where the battery is located. Hydrogen is lighter than air and will travel up until blocked. A simple hole in the top of the compartment will work.


With the proliferation of sealed batteries some people have asked, well, if the battery is sealed why do I have to ventilate the battery? Because sealed batteries can vent hydrogen. They are what is known as Sealed Valve Regulated or SVR batteries. The valve is there to vent hydrogen if the battery overheats and overpressures. Under normal operating conditions they don't, but they can. The space that the battery is in needs to be vented.


The battery has to be secured so that it can't move around. That means it can't move more than one inch forward and aft, sideways, or up and down.
Again, a battery box will help but then the box has to be secured. Most battery boxes or trays come with a strap to hold them down.
If a metallic fuel line passes within one foot of the top of a battery there must be some sort of shield to keep the battery terminals from making contacting with the battery terminals, and so if there is a fuel leak it won't drip or flow onto the battery.
A battery cannot be installed directly over or under a fuel tank, fuel line fitting, or fuel filter. That's pretty obvious. Keep the battery away from fuel system components.
Battery terminal connectors must not depend on spring tension to stay connected. Use the type of battery cables that tighten with a bolt.


IGNITION PROTECTION:
Each electrical component that is in a space where fuel fumes can accumulate must be ignition protected.
If an electrical component is in the engine room, fuel tank space, or space where there are fuel lines, then the electrical component must be ignition protected. What does ignition protected mean? It means that a spark from the device will not ignite a fuel/air mixture in the same space. In simpler words, it won't cause an explosion.
This means that alternators, generators, circuit breakers, battery switches, electric fan motors, electric fuel pumps, distributors, etc. must be ignition protected. How do you know if it is? If you buy a marine engine from any of the major suppliers of marine engines, they come with ignition protected equipment. Make sure you buy only marine components. The automotive part may look the same but it just might kill you. Also, many marine suppliers have their parts tested by Underwriters Laboratories. Look for the UL Marine Label. If there is no label, and the manufacturer cannot satisfy you that it is ignition protected, don't buy it.
If you are marinizing or rebuilding marine engines, you must install ignition protected electrical components. So when you order be sure to specify that they be marine parts.
DO NOT use staples. Don't staple the wire to bulkheads and stringers. The metal staples cut through the insulation. They create a HARD SPOT. That's a point where stress is concentrated. That's where the wire breaks.
DO USE good marine grade clamps or straps to hold the wire in place, or use conduit or wire loom. However


WIRING: General
Each conductor must be insulated, stranded copper wire.
DO NOT use solid conductor, aluminum conductor, ROMEX, or anything other than a good copper marine grade wire. Wiring in boats is subject to severe shock, vibration and flexing. Stranded wire is required because it is more flexible and if one or two strands break, you still have a connection. Use UL boat cable labeled UL 1426.
*Each conductor or group of conductors must be supported by clamps or straps not more than 18 inches apart. or:
*The conductor or group of conductors may be enclosed in a rigid duct or conduit.
*The clamps or straps must not chafe or abrade the conductors.
*The above three rules are not Federal Regulations, they are ABYC standards. In fact they were part of the Federal Regulations until the mid 1980's when the Coast Guard took them out of the regulations to comply with the Reagan administration's policy on deregulation. However they are good practice when installing wiring. Wiring should not be just snaked through the boat. You want it to be neat and run in bundles so it is easily traced if there is problem, and easily replaced. Plus it is protected against vibration and shock when bundled. You don't want it getting in the way of access to the engine or other components so give some thought to how it is routed and secured in place. You may use more wire this way but it makes a much better, safer installation.

DO NOT just hang the wire through the boat. Support it. You don't want the wiring moving around, swaying back and forth, and loose in the boat. This is dangerous. It will cause the wiring to fatigue and break, and chafe against other parts of the boat.
DO NOT use staples. Don't staple the wire to bulkheads and stringers. The metal staples cut through the insulation. They create a HARD SPOT. That's a point where stress is concentrated. That's where the wire breaks.
DO USE good marine grade clamps or straps to hold the wire in place, or use conduit or wire loom. However, if you use wire loom use wire loom that is self-extinguishing.

Continued Next Post


 

Bamby

New member
Low Voltage Wiring: Less than 50 volts
Low voltage conductors must comply with SAE standard J1127 and J1128 and the insulation temperature rating of SAE J378b or UL standard 1426.
Look at the labeling on the wire. Does it say UL Marine? Does it have an SAE or ISO rating? If there is no label on the wire is the spool or package labeled? Many wire manufacturers don't label the wire but they do label the package it comes in.
DO NOT use wire that has no labeling on the wire or on the spool or packaging.
DO NOT go to your local auto store and buy automotive wiring off the shelf! Get your wire from a marine supply. Ask them if it is labeled and what the label says.
DO NOT USE ROMEX.
DO USE UL BOAT CABLE.


High Voltage Wiring: 50 Volts or more.
High voltage wires have specific standards as well. They must meet one of the following standards:
(1) A conductor that has insulation listed and classified moisture resistant and flame retardant in Article 310, NFPA No. 70, National Electric Code;
(2) A flexible cord type SO, STO, ST, SJO, SJT, or SJTO listed in Article 400, NFPA No. 70, National Electric Code;
(3) A conductor that meets IEEE Standard 45.
(4) A conductor that meets UL Standard 1426.
If it meets one of the above it can be used in high voltage circuits. The most commonly used wire is UL 1426 boat cable. For 120 Volt AC systems the recommended wire is UL Boat Cable triplex wire. On the outside this looks just like triplex wire used in houses. Look at the labels on the wire. It should say UL 1426 or UL Boat Cable.
DO NOT USE HOUSE WIRING.


Where the nominal circuit voltage of each of three or more current carrying conductors in a duct, bundle, or cable is 50 volts or more, the amperages of each of those conductors must not exceed the value in table 5 multiplied by the correction factor in note 2 to Table 5 for the number of conductors that carry 50 volts or more.
What that means, is that wires in a bundle or in ducting can a higher current than single wires. See the notes on the table. Table of Allowable Amperage of Conductors


Exceptions: This section does not apply to communication systems; electronic navigation equipment; resistance conductors that control circuit amperage; conductors in secondary circuits of ignition systems; and pigtails of less than seven inches of exposed length. So the above does not apply to the wiring inside your radios, GPS, radars or to the ignition wires on the engine.


Continued on next post
 

Bamby

New member
Ignition Wire:
Sec. 183.440 Secondary circuits of ignition systems.
(a) Each conductor in a secondary circuit of an ignition system must meet SAE Standard J557.
Since this regulation was published the standard has changed but the Coast Guard has not updated the Federal Regulation to match the SAE standard. SAE standard J557 no longer exists. The current SAE standard for marine ignition wiring is SAE J2031, which also covers road vehicle ignition wiring.
(b) The connection of each ignition conductor to a spark plug, coil, or distributor must have a tight fitting cap, boots, or nipple.
ABYC P-4 Marine Engines and Transmissions Says.
4.6.14.4 High tension ignition cable assemblies shall conform to SAE J1191, High Tension Ignition Cable Assembly.
4.6.14.5 Ignition distributors shall conform to SAE J1294,Ignition Distributors or UL 1120, Marine Engine Ignition Systems and Components.
So all ignition wiring, wiring assemblies, distributors and the boats caps and nipples should be made for marine use.



If you purchase engine packages from one of the marine engine suppliers then the engine wiring will be pre-installed and meet all of these standards. You are responsible for making sure wiring leading to the engine complies with the regulations. However, if you do your own marinizing, or engine rebuilding then you must make sure the wiring on the engine is up to the standard.


Protecting Conductors:
Wires need to be protected from shock, vibration, abrasion, and flexing. In addition they should be laid out so they do not make sharp corners. They should be laid out neatly so there is easy access, and easy replacement, and do not make contact with hot parts such as exhaust manifolds, or hang in the bilges.
(a) Each conductor or group of conductors that passes through a bulkhead, structural member, junction box, or other rigid surface must be protected from abrasion.
Wires should be supported using clips or straps, at least every 18 inches (45.5 cm), throughout their, length, and where they pass through bulkheads or other structure should be protected from abrasion by grommets or some other non-abrasive material. You do not want a wire abrading through particularly if it passes through something that is conductive like metal panel boxes or metal boat structure.
(b) Each ungrounded terminal or stud that is continuously energized must meet Sec. 183.455 or must have a boot, nipple, cap, cover, or shield that prevents accidental short-circuiting at the terminals or studs.


Positive terminals, such as the positive terminals on the starter, solenoid, alternator and other electrical equipment must be covered with a rubber boot, cap or nipple so that metal tools won’t accidentally come in contact with them. Battery terminals were already discussed, but just as a reminder they need to be covered as well. The amount of energy released when a wrench or screwdriver accidentally comes in contact with one of these terminals can be truly frightening, and start a fire or cause an explosion if fumes are present.


Connections:
Solder must not be the sole means of connection between two or more conductors or between a conductor and a connector.
What? I can't use solder? Yes you can, BUT, it must not be the only connection. You must also have some sort of mechanical connector, such as crimp type connectors, that hold the two wires together. When you solder the wire it becomes essentially a solid single conductor wire. It forms a hard spot in the wire that concentrates the stress at that point and becomes prone to breaking. So use a connector as well as soldering. Some marine wiring experts even advocate not using solder at all. But this is a matter of opinion. Some think the acids in the solder cause corrosion, others disagree. So if you do solder, use an acid free solder and make sure it is good solid solder not a "cold solder"


The same applies to connectors inside of junction boxes and electrical panels.


DO NOT USE WIRE NUTS! They do not supply a good mechanical connection and they are prone to vibrating off. They also allow moisture to collect inside the wire nut, causing accelerated corrosion of the wire. The corrosion raises the resistance of the wire creating heat, and causing a large voltage drop at this point, which means you will not be getting full voltage down stream, at the appliance. Low voltage at the motor, light, or other appliance you are running causes the item to overheat and burn out.
This is another item that was in the Federal Regulations, but was taken out in the deregulation process. However, it is still good practice not to use wire nuts. There are some manufacturers of wire nuts who claim their product can be used on boats. Don't do it. They have the same problems as regular wire nuts.


ABYC is very specific:
11.16.3.6. Twist on connectors, i.e., wire nuts, shall not be used.


Exception. Sometimes wire nuts are used inside of appliances such as refrigerators and washers and dryers. These do not have to be removed.


Continued on next post:
 

Bamby

New member
OVER CURRENT PROTECTION:
Each ungrounded current carrying conductor must be protected by a fuse or by a manually reset trip-free circuit breaker.
This means that the hot wire, that is the positive wire in DC systems, must be protected. The negative wire does not have to be protected. However, you can use circuit breakers that break the connection in BOTH positive and negative at the same time for even better protection. There is often confusion here. The circuit breaker or fuse is not there to protect the motor or appliance. CIRCUIT PROTECTION IS THERE TO PROTECT THE WIRE. Too much current in the wiring causes it to get hot, melt the insulation and start a fire.


If there are still any positive ground systems out there in the world, everything is then reversed from what I am saying here.
What in the world is a manually reset, trip-free circuit breaker? Obviously it is a circuit breaker, but what does the rest mean. Well, it means it can't automatically reset itself. You have to manually reset it. Trip free means you can't hold it in the on position while there is still a fault. If the circuit is going to trip the breaker, it must trip whether you are holding it place or not.


Look for the UL MARINE listing on the package.
DO NOT USE circuit breakers intended for house wiring! They are not designed for marine use and are not ignition protected.
DO protect all circuits.
The only exception is the starter motor circuit.


Location of Overcurrent Protection
The fuse or circuit breaker must be within seven inches (17.8 cm) of the source of power.
Exceptions:


Exception 1. If it is physically impractical to put the fuse or circuit breaker within seven inches of the source of the power it can be up to 40 inches (101.6 cm) away, if the wire is contained for it's entire length between the source of power and the circuit breaker, in a sheath or an enclosure.
This has been interpreted many ways. The obvious is a conduit. But who uses conduit on a boat? Maybe on really big boats. Putting a sheath such as wire loom or heat shrink wire covering over the wire works. Some even say that wrapping it in electrical tape is ok. I think that this is really a shoddy way to do it and not very professional. There are many different wire sheaths available, some that are fire resistant. Also if the wire is in an enclosure such as a panel box or electrical box then it is ok. The whole idea here is to protect the wire in such a way that if it overheats it doesn't set the boat on fire. Here are some links so you can see what I'm talking about.


The following links are not an endorsement of these products by the author. The are just presented as examples of products available.
CableOrganizer.com Oxide.com Heat Shrink Tubing
Exception 2. Each ungrounded output conductor from a storage battery must have a manually reset, trip free circuit breaker or fuse, unless the conductor is in the main power feed from the battery to the cranking motor. The fuse or circuit breaker must be within 72 inches (182.9 cm) of the battery, unless it has a battery disconnect switch.


The above distances are measured along the wire. In other words we are talking about wire length, not the straight line distance from the power source to the fuse or circuit breaker. Also note, this is only in the output conductor (wire) from the battery to the cranking motor (starter). The obvious solution here is to install a battery switch as close to the battery as possible and that is what most boats have. Just make sure you use a good quality UL listed switch. There are a lot of cheap, poor quality fakes on the market. Buy a good brand name. Why? Because a lot of current flows through this switch, and when the switch is thrown sometimes arcing occurs. You want a switch that can stand up to this. I have seen cheap ones that melted or caught fire.


Sizing Circuit Breakers or Fuses:
Circuits of less than 50 volts: (DC Circuits)
A circuit breaker of fuse should not be rated for more than 150% of the amperage that the circuit is rated for. Suppose you have a 30 amp circuit. Then the circuit breaker or fuse should be no more than 45 amp. This is so it will blow, but not blow for the occasional spike in current that occurs when you first turn on a piece of equipment. You don't want it rated higher than this because then the wire may burn before the breaker trips.
Circuit breakers in low voltage DC circuits should break only the positive wire.


Circuits of 50 volts or more: (AC circuits)
The circuit breaker or fuse should be sized at the same amperage as the circuit. If you have a 30 amp circuit then the breaker or fuse should be 30 amps. If you can't get the exact size then it should not exceed 150%. Sound familiar? But it is best to rate it at the amperage rating for the circuit.



Circuit Breakers in AC circuits should be double pole, that is, break both the black and white conductors at the same time.
For all circuits the voltage rating of the fuse should be the same as the circuit voltage. It the circuit is 12 volts then the breaker or fuse should be 12 volts. If it's 120 volts then it should be rated for 120 volts. Do not mix breakers. Yes, you can use a 120 volt breaker on a 12 v circuit, but definitely don't use a 12 volt breaker on a 120 volt circuit. But you should use a breaker or fuse sized for the correct voltage.


Special Applications:
There are some special circumstances that permit a variance from the above.


If it is the power feed from the battery to the starter it does not have to be fused. However, make sure the wire is sized correctly because this circuit carries a lot of current when you try to start the engine. Also try to locate the battery so that this wire is as short as possible. Don't get fanatic about it, but the shorter it is then the less resistance the wire has and the more power you get to the starter.


Today most engines have alternators (AC) rather than generators (DC), And most alternators have a built in regulator that makes them self limiting, but there are still some around that aren't. If the alternator or generator is not self limiting then there must be a fuse or circuit breaker on the output, and the breaker or fuse cannot be rated for more than 120% of the maximum current output at 60 degrees C. This is generally not something the boatbuilder or owner has to worry about because most buy an engine package from one of the engine manufacturers and all this is done by them. But you should be aware of it. If the alternator or generator is self limiting then this requirement doesn't apply. Ask the people you buy the package from if the alternator is self limiting, that is does it have a built in regulator.

Continued next post:


 

Bamby

New member
WIRE SIZES:For wire sizes see the table listed below.
Table of Allowable Amperage of Conductors
What do we mean by wire size? It means the actual physical size of the wire in mils, usually stated as wire gauge. Simply, how thick or thin is the wire? The concern here is resistance and voltage drop. Resistance and voltage drop are are caused by two things, the size of the wire and the length of the wire. The thinner the wire the more resistance it has and the longer the wire the more resistance it has. So, there is not much you can do about the length of the wire except move things closer but that is often not an option. So then you have to size the wire so that it has the least resistance and less voltage drop. Here is link to Wikipedia that explains American Wire Gauge.


Why? All electrical and electronic equipment is designed to work at a specified voltage. If the voltage is too high it can burn out the equipment. If the voltage is too low it can also burn out the equipment. We are concerned with too low. If a wire has too much resistance the voltage will drop from the high of say 12 volts to maybe 11 or 10 volts at the other end. For example, starters require a constant voltage and high current. If the voltage drops they slow down, and get really hot. So we need to make the wire the right size to give the starter the right voltage. This also causes the wire to heat up and if it gets too hot, melt the insulation and set things on fire.


Wire comes in various sizes from really big at 000 gauge (ga) (sometimes shown as 3/0) to really small at 22 gauge and even smaller sizes. The smaller the size the bigger the number of the gauge. On a boat, the smallest you can use is 16 gauge. Except, you may use 18 gauge in sheathed wire bundles. This would make you think, the bigger the better. That's not the case. The best way is to figure the wire size you need and then go one size bigger (smaller gauge). For example battery cables are typically 4 gauge but can be as large as 0 gauge. It depends on the battery capacity.


How To Calculate Wire Size .
Wiring Color: Electrical Color Codes:
See a sample wiring diagram here . This is a basic wiring diagram and only meant to be used as a training aid.


See sample US Coast Guard Wiring diagrams:
USCG-WiringDiagram-Inboard-IO_Runabout.pdf
USCG-WiringDiagram-Cruiser-LowV-DC.pdf
USCG-WiringDiagram-Cruiser-AC-DC.pdf
USCG-WiringDiagram-Aux.Sailboat.pdf
InstrumentWiring.pdf
Diagram4Harness.pdf


Reference Guide to Periodical Articles. My own page of references to articles in boat building and boating magazines. Many of these are on electrical systems.


Basically that's it. These are the requirements. But remember that this is the minimum you must do. If you really want to do electrical systems right it is best to follow ABYC standard E-11, DC and AC Electrical Systems For Boats. Also on Ike's List you will find references to electrical sites on the internet, and references for books on electrical systems for boats.


Last Post of the original series. Had a brief description of post topic originally that had to be deleted to post formatted material in a sensible way here. Hoping some of you find it useful resource when working on your boats, or modifications.
 
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