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Basic Electricity 1 2 3 4 5 6 7 8 9 10 11 Electrical Pages Index
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If you know little or nothing about electrical circuits go to, If you have training or experience in electricity and electrical circuits; 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!
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. 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. 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 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. See the photo at the top of the page. 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. 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. |
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