The Electrical Side of Boating


Tips about Marine Wiring, Crimp Connectors and More By Jack and Alex Wilken


The scope of this month’s article


is to cover some of the elements of marine wiring. These include wire, crimp connectors, cable ties and tape. By starting with appropriate materials and tools you will have the possibility of doing a professional job.


Stranded marine-grade wire is


required for AC (120 volt) circuits on boats. AC circuits on boats must use 600 volt 3 conductor stranded and sheathed marine grade cable Cable Ties- Both DC or AC wiring


Figure 1 Marine wire is multi-strand and preferably tinned—not single strand (Romex).


Wire- Marine wiring requires both


flexibility and resistance to corrosion. House wiring is protected by walls so it is not subject to movement and vibration. Wiring and connectors in boats, however, are bounced about constantly, vibrated, and subjected to high temperatures, water, and chemicals — some corrosive. Solid wire (Romex) and wire nuts used in houses are explicitly banned by ABYC. (Figure 1) For flexibility and corrosion resistance, marine wiring consists of multiple copper wires in a common insulating jacket. It is not required that wiring be tinned but that does reduce or slow corrosion. Wire size for 12 volt DC systems are calculated by adding the distance from the source, the DC breaker or buss to your device, and back to ground — the round trip distance. If you need to determine amperage from watts, it is calculated as Amps = Watts divided by 12 volts. ABYC tables give you the minimum size wire required for amperage load. Wire size used on the ABYC table is measured in gauge (AWG = American Wire Gauge), the larger the number the smaller the diameter wire. AWG 16 is the smallest gauge wire approved by ABYC for any DC wiring. Check ABYC specs for exceptions.


48° NORTH, AUGUST 2011 PAGE 32


must be secured in such a way as to minimize movement and to prevent it from falling against anything that could damage the insulation. The most common method of securing wiring is with plastic cable ties (also called zip ties or tie wraps). These must be spaced at no more than 18 inches apart. The wires need to be slack enough to put no strain on connectors or cause insulation to chafe or degrade but not so loose as to be able to fall into anything that would harm the insulation. Use wire ties with an included screw connection


weight from the wire without it coming out of the crimp fitting. To meet this you must use the proper crimp tool. This means using marine CCs with nylon jackets and attaching them using a ratcheting crimper. (Figure 3) The use of crimp fittings with vinyl jackets and inexpensive crimping tools which are typically used on automobiles do not meet marine standards and are not safe.


Marine CCs have nylon jackets that


are much more rugged and puncture resistant. They are easy to recognize by their semi-transparent jackets, and come in a full range of sizes. Ratcheting crimpers can be found at marine suppliers for around $75 to $100. For applications where the wire is


to be screwed down, ring connectors should be used. Curling the wire into a hook is not an acceptable solution for marine use. A ring connector is not required with some equipment that uses a compression plate with screws or nuts to squeeze the wire, but it is still a good idea. The flat forked connectors are banned by ABYC, but forked connectors with small hooks on the end of the forks are acceptable in cases where it is hard to remove and replace the screw. (Figure 4) Butt connectors are to be used to


Figure 2 Wire terminals must be crimp type connectors.


or a separate cable tie mount to secure wiring against bulkheads. Split wire harness conduit or spiral wrap helps secure and protect wire runs. A battery terminal must have a


mechanical connection that does not depend on a spring. Crimp connectors- (CCs) are the


preferred method of splicing wires or connecting wires to circuit breakers, buss bars or equipment. (Figure 2) ABYC standards specify that once crimped, the connector must withstand a certain force attempting to pull the connector off the wire. For example, an AWG 14 wire and connector that might be used to power a bilge pump must be able to withstand 30 pounds of force attempting to pull the connector off. This means the ability to hang a 30 lb.


splice two wires. This is a tube where the two wires are inserted into the two ends and then crimped. Step- down butt CCs are available that allow two different wire sizes to be spliced together; however, in most cases, the same size wire should be used throughout a project.


Figure 3 Use a ratcheting crimp tool, not the cheaper automotive type.


When using CCs that may be


exposed to water such as applications in bilge, engine spaces, or above decks, nylon CCs are available with


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