Working with Wiring Diagrams not have it in stock is 45 minutes away. What do you do? Often, one or more of the various colors for wiring to the ABYC recommendations may not be readily available at the time you perform a repair, and substitution may be the only practical solution. It’s perfectly OK to use one of the other colors provided you code both ends of the replacement wire with the proper color and then make a prominent note on the wiring diagram. The best code medium in this case is colored heat-shrink tubing, but, of course, brown heat-shrink is less likely to be available than brown wire. In this case you could make do with a written label wrapped around the wire and protected with waterproof tape. When you substitute wire colors, circuit ID becomes doubly important.
Expanding the Basic Circuit Expanding the elements of the basic circuit to include the components shown in figure 2-6, you end up with something that looks very much as it might look if it were wired on your boat, even though this might be hard to see in this compressed state. In this diagram, I am illustrating what the wiring for a bilge blower circuit would look like if we backtracked to the master switch panel on the boat. Figure 2-7 on page 20 illustrates what the power supply circuit to a master switch panel should look like, with a circuit protector (fuse or breaker) and battery master switch installed. I should point out, however, that many boats do not use a battery master switch, and many installations don’t have the fuse or breaker installed either. The latest version of the ABYC’s electrical standard E-11 states that “A battery switch shall be installed in the positive conductor or conductors from each battery or battery bank with a CCA rating greater than 800 amperes.” You’ll have a lot more information on batteries and battery banks in chapter 5. For the moment, suffice to say that many small runabouts with only one small battery could easily fall below this 800-amp threshold, and would be exempt from the recommendation for a battery switch. I should also point out that even though switches are not recommended for these
Negative Bus Bars
Bilge Blower Showing positive and negative return wires through switch panel
Circuit Breakers/ Switches Positive Bus Bars
Fig. 2-6. A bilge blower circuit highlighted on the switch panel, with the key components identified. When looking at large clusters of wires in an arrangement like this, it’s important to focus on only the components and wires that are important to you at the moment. To begin your search, start at the wiring at the back of the switch or breaker labeled “blower” in this example and carefully tug on the wire to follow it through any bundling at the back of the panel. Once you’ve identified all the wiring behind the panel, locate the component in question on your boat. A good wiring diagram may indicate a relative component location on the boat, but don’t count on it: usually you have to search on your own to find all the components in a given circuit.
small batteries, 800 CCAs is more than enough current to start a fire and cause serious burns in the event of a short. Thus, a means of quickly disconnecting these small batteries is no less important than it is for the big guys, in my mind. All batteries, regardless of CCA rating, should have a master shut-off switch.
Chasing Circuits Remember that the distribution panel (or panels— sometimes there are more than one) on your boat is the point at which most of the circuits on your boat come together in close proximity, and the situation 19
