Fuses are normally provided only in the circuits supplying auxiliary loads, such as horns, running lights, cabin lights, spotlights, and communications equipment.

All other circuits, such as the starting motor circuit, solenoid switch control circuit, battery charging circuit, and power supply to the distribution panel, are unfused. This is because the possibility of short circuits or leakage currents is reduced by use of the following equipment, components, and systems:

1. Two-wire, ungrounded electrical system instead of single-wire, grounded

2. Two-wire, ungrounded electrical com-ponents of such rugged construction as to make grounding of internal wiring or terminals difficult under normal service conditions

3. Watertight components, such as battery connection boxes, a distribution and control panel, and a starting motor solenoid switch

4. Cables between batteries and starting motor of sufficient size to carry high inrush currents and provided with terminal lugs and end sealing to prevent penetration of moisture

5. Splash guards for attached generators/ alternators

6. Sealed meters or transparent splash shields to protect instruments such as battery charging ammeters

7. Fusing of auxiliary load circuits so that faults in these circuits can be isolated

When you are working around an engine or boat, it will be to your advantage to pay particular attention to how a unit is wired and what type of wiring is used. These observations will make your job of finding and repairing troubles much easier.

When you are on a small boat away from the ship, it will be rather difficult for you to check out a system completely because all the required test equipment will not be available. However, you can check for such things as loose or corroded connections, broken wiring, faulty switches, and burned out lamps or fuses. You can obtain detailed information pertaining to a particular installation from the appropriate NAVSEA technical manual.