In preparing this manual. MARINCO has relied upon electrical standards established by the National Electric Code and the recommended practices and standards for design and installation of AC electrical systems for vessels prepared by the American Boat and Yacht Council. Inc. This manual reflects practices and standards in effect at the time of publication and is intended only to be a guide to understanding common AC electrical systems used aboard boats. MARINCO will not be liable for any loss, damage, incidental, or consequential damages of any kind, arising in connection with the use of, or reliance upon, this manual.
This manual is intended to provide you with a basic understanding of AC electrical systems used by major boat manufacturers in the United States and Canada. It is also our intention to familiarize you with some MARINCO products and their installation that can make your boating activities more pleasurable.
A Glossary of Electrical Terms
- The standard unit used to measure the strength of an electric current; that is, the number of electrically charged particles called electrons that flow past a given point on a circuit each second Commonly called "amps".
Circuit Breaker - A device designed to interrupt the circuit when the current flow exceeds a predetermined value in addition to protecting the circuits of your boat, circuit breakers enable you to turn off the power in a circuit so you can work without the danger of a shock.
Ground - Ground applies to the potential of the earth's surface. which is zero
Grounded Conductor - A current carrying conductor connected to the side of the source which is intentionally maintained at ground potential This is referred to as the neutral conductor in AC electrical systems and is white in color.
A ground fault is an electrical circuit that permits current to flow from hot wire to ground Faults occur as a result of worn insulation, moisture. and deterioration in tools or appliances.
Ground Fault Circuit interrupter - A device intended to interrupt the electric circuit to the load when a fault current to ground exceeds a predetermined value (usually around 5 miliamps) that is less than that required to operate the circuit breaker of the supply circuit.
- A conductor. not normally carrying current. provided to connect the exposed metallic enclosures of electrical equipment to ground for the purpose of minimizing shock hazard to personnel. In AC electrical systems this is referred to as the ground wire and is green in color.
Kilowatt - A unit of electrical power equivalent to 1.000 watts. Used commonly as a measure of AC electrical output for marine auxiliary generators.
- A female connector providing a source for electrical current. An outlet or receptacle is a line fitting.
- A male plug containing the conductors for the power circuit and the grounding conductor for an electrical device such as a light, appliance, or electrical equipment.
- A single panel or group of panel units designed for assembly in the form of a single panel: including buses, circuit breakers. and with or without switches for the control of light. heat or power circuits: designed to be placed in a cabinet or cutout box placed in or against a wail or partition and accessible only from The front
Polarized System - A system in which the grounded (white) and ungrounded conductors are connected in the same relation to ail terminals or fixture leads on all devices in the circuit
Ungrounded Conductor - A current carrying conductor which is completely insulated from ground and connects the source of power to the utilization equipment. This conductor is connected to the "hot" side of the shore power system or to the appropriate terminal of an on-board auxiliary generator and is red or black in color.
Volt- The unit that measures the potential difference in electrical force, or "pressure" between two points on a circuit The current at most receptacles and lights is at a pressure of 125 volts. As the current moves from the hot supply wire through the load presented by the appliance or light. it loses voltage in doing the work. When the current leaves the load and enters the return circuit provided by the grounded conductor. it has lost all voltage and is at zero pressure, the same as The earth.
- The unit of power it indicates the rate at which a device Converts electric current to another form of energy. either heat or motion it is the rate at which a device consumes energy. A rule of thumb formula for figuring the approximate watts available is: amps x volts = watts