Wire It Right
More breakdowns can be traced to electrical failures than to any other cause. Whether you're troubleshooting an engine or have an equipment problem, the first thing to check is the electrical power supply. Of course, it helps if you understand your boat's electrical system. You should become familiar with wiring basics if for no other reason than electrical faults can result in deadly consequences ? namely, fire. Never tackle electrical repairs without knowing the principles and techniques that apply.
Knowledge of home wiring systems does not translate directly into a grasp of marine procedures because the two environments ? especially if you do your boating in salt water ? are so different. Water, vibration, high heat, sunlight and oil are all detrimental to wiring. Never hire a home electrician to work on your boat unless you know that he is also schooled in marine wiring and repair. Again, when working on electrical problems yourself you must first understand the circuitry involved. That goes double for the AC system.
Wiring know-how does not only come in handy if a problem occurs on the water, but it can also save you money. Qualified marine electricians usually charge more than do the land-based variety. If you know what you're doing, you can install electronics, bilge pumps, lights, outlets, etc. You can also replace substandard wiring and turn a rat's nest of wires into a neat installation.
The first rule of marine wiring is to use the right materials and tools. Home improvement stores may stock some of these, but marine supply stores are where you should shop for your wire, terminal fittings or connectors, switches and breakers. Water and fire resistance are paramount. Ancor is a time-honored brand for marine-grade electrical supplies. You can find them at marinco.com. The second rule is to remember that each step is equally critical and to reject any shortcuts. The more protection you can provide to keep wires from overheating, the better.
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Step-By-Step TAKE IT OFF. Wire stripping is a delicate process. Never use a razor blade or a pocketknife to remove insulation because of the potential to also remove some strands of wire or nick the wire, which leads to quicker corrosion. Always use a wire stripper. Various types of wire strippers are available, including the pistol-grip automatic type. The pair shown here is handy because it is compact and can get into tight places, such as around gauges. Make sure that your wire stripper is for AWG wire and not SAE wire, which is smaller. As for the wire itself, use only stranded (not solid), tinned (silver-colored), copper wire that is rated BC5W2. This should be printed on the wire along with size, temperature capacity and the words OIL RESISTANT. The ABYC stipulates particular colors and color combinations for various uses that may be applicable to your boat. This information, as well as the proper size wire to choose for different amperages and run lengths, is available at the Ancor web site under Support/Wire Tech Data. After stripping the end of the wire, always make sure to twist the strands tightly together before inserting them into the connector. TERMINAL TALK. For the best connection, use heat-shrink, crimp-style, tinned- copper terminal fittings for attaching wires to gauges, terminal blocks and electrical panels. Butt connectors are commonly used to splice wires. While the best connection is made using a terminal block, which lessens the chance of separation and lowers current resistance, damaged or severed wires can be repaired with butt connectors. Never use wire nuts or electrical tape to splice wires. Terminals should be matched to wire by size, although they usually serve more than one size (e.g., 12-10). Note that wire size increases as the numbers get lower (18-gauge wire is larger than 22-gauge wire). Shown here are a ring connector and a butt terminal. Terminals are color-coded according to size (e.g., yellow: 12-10 AWG; blue: 16-14 AWG). Strip off only enough insulation so that the wire fills the metal barrel of the terminal. Hold the insulated wire end next to the terminal to see how much to strip. Step-down butt connectors can be used for joining wires of different sizes. PROPER PRESSURE. Before crimping the connector, slip a length of heat-shrink tubing over the wire ? long enough to go from the terminal's head to at least an inch past its insulation. Heat-shrink connectors are many times more costly than non-heat-shrink connectors, which is why you're likely to find the latter type on your boat. If you choose to use the less-expensive type, perhaps because you're doing extensive rewiring, then use heat-shrink tubing. Here, it's redundant. But the use of both heat-shrink connectors and heat-shrink tubing forms the most watertight connections. Heat-shrink tubing comes in various diameters, lengths, colors and shrinkage ratios. Use either 3:1 or 4:1 with an adhesive lining (dual- or heavy-wall). Use crimpers that are marked to correspond to connector sizes. Avoid using punch-type crimpers made for bare metal crimps. Instead, use "compression" or eliptical crimpers (shown here) because they will not puncture the insulation. To test a crimped connection, simply tug hard on it. You should not be able to pull the wire out of the terminal. TURN UP THE HEAT. Some electricians still prefer a soldered connection, but a properly made crimp connection is often less brittle than a soldered connection and just as strong. After crimping, use a butane torch to shrink the terminal's insulation tightly around the wire. Never use an open flame in an area where fumes could possibly be present. The space should be well ventilated and no fuel or solvent should be nearby. Safer than a torch is a hot-air gun with a nozzle made specifically for the task. You can hold the heat gun in your hand and work in tight spots where an open flame might affect something nearby. The heat gun can also be placed in a stand, freeing up both your hands to control the wire. Apply heat carefully, especially with a torch, to avoid burning the insulation. GIVE IT A NAME. Push the heat-shrink tubing up to the terminal itself and shrink it tightly onto the terminal and wire. Always label your connections. White heat-shrink tubing can be written on with a marker to label wires. Another method is to make small labels and cover them with clear heat-shrink tubing. A ring terminal (shown here) is far superior to a spade (forked) terminal and should always be used to make connections to a post if possible. The ring should fit tightly around the post. If it's loose, it can result in a poor connection. When attaching more than one connector to a post, separate them with nuts. Use a lock washer under the final nut. When connectors must be attached with screws, a magnetic or split-shank screwdriver will hold the screw in places that your fingers can't get to.. OUTSIDE SUPPORT. Wires should be supported so that they don't sag, move or contact water. One method is to use wire ties to hold them in place and to fasten them to sidewalls, headliners and bulkheads. For fastening to a surface, use wire ties that have screw holes in them. Between these ties, which should be spaced about a foot apart, use regular wire ties when running two or more wires. Wire ties hold wires in place but do not protect them from chafing or from damage by something or someone contacting them. Use split-loom or plastic spiral wrap, or some other type of "raceway" over the wires to protect them, and use rubber grommets wherever wires pass through a bulkhead. Whatever type of conduit you use, make sure that it won't burn. In addition to wire ties, a variety of plastic (not metal) clips are available for support. Always keep wires as high as possible in the bilge so that there is no chance they can become submerged. |
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More Wiring Tips ? Shut off all power before working on the electrical system. |
