PIPE AS 3920250 - Caterpillar

Grounding Practices
The electrical system for the vessel and the engine must be properly grounded. Proper grounding is necessary for optimum engine performance and reliability. Improper grounding will result in uncontrolled electrical circuit paths and in unreliable electrical circuit paths.Uncontrolled electrical circuit paths can result in damage to main bearings, to crankshaft bearing journal surfaces, and to aluminum components. Uncontrolled electrical circuit paths can also cause electrical noise. Electrical noise may degrade the performance of the vessel and of the radio.The negative terminals of the alternator, the starting motor, and all of the electrical systems MUST be connected to the negative battery terminal. The alternator must meet marine isolation requirements. The starting motor must also meet marine isolation requirements.For engines which have an alternator that is grounded to an engine component, a ground strap MUST connect that component to the negative battery terminal and the component MUST be electrically isolated from the engine.A bus bar with a direct path to the negative "-" battery terminal is permissible and recommended for use for all components that require a negative "-" battery connection. The bus bar should be directly connected to the negative "-" battery terminal. A bonding cable should also be connected from the cylinder block to the bus bar on the negative "-" battery connection.Use of a bus bar ensures that the Electronic Control Module (ECM) and all of the components that are connected to the ECM have a common reference point.Refer to Special Instruction, REHS1187, "Marine Engine Electronic Installation Guide" for additional information on grounding procedures.