We’re all familiar with how circuit breakers work in a home or apartment, but how exactly do marine circuit breakers operate? What’s the difference between DC and AC circuit breakers, and in what instance can you use them? Should you have both a DC and AC circuit breaker, what’s a residual current circuit breaker? I will be answering all these questions for you in this post.
A circuit breaker, at its core, is an electrical switch that is automatically operated to protect electrical circuits from being short circuited or overloaded. The default, automatic response is to cease operation until manually or automatically reset. Circuit breakers have been designed for a multitude of items; I will deal primarily in those relating to Blue Seas Circuit Breakers. Keep in mind that every boat requires a different type of circuit breaker system, while 12-volt direct current circuit breakers are by far the most widely used in marine vessels.
Blue Seas DC Circuit Breakers – DC short for direct current; originally the main means of distributing electrical power was through direct current so DC circuit breakers were the first circuit breakers for our energy needs. Direct currents flow has one and one only ‘unidirectional’ flow of electrical charge one a constant direction, e.g. batteries or solar cells so the DC circuit breaker must respect that one direction charge. Reversing polarity would result in safety issues and irreversible damage. DC circuit breakers must be built to maintain arc voltage that will interrupt the current, at low currents. DC currents are constant currents, while AC is sinusoidal current (alternates current waves + or – 60 or 50 times. To interrupt DC flow, it must be forced to zero by the circuit breaker.
Blue Seas AC Circuit Breakers – alternating current circuit breakers are what are typically used in houses and complexes. Alternating current is named such due to its rapidly changing directional nature. AC circuit breakers must be able to stop current that may reverse direction at any moment. Like direct current, alternative current circuit breakers must break the flow of energy in dangerous situations. On board generators can power ac circuits. The stopping system for alternating current is much more complicated than direct current. The arc must be interrupted with metal and non-metal components in a series of basic physical steps. The components are composed of switches, contact locations, catches, electromagnets, and terminals. In a nutshell, charge flows through the fuse wire which is designed to disintegrate when temperature rises above a certain point, a dangerous temperature. With the destroyed fuse, the circuit is then opened and contains the energy to stop damage to the surrounding area.
AC/DC Circuit Breakers – some boats implement a system of both AC and DC energy, thus having AC/DC circuit breakers is necessary in preventing electrical emergencies. A power inverter can convert alternating energy into direct current, or vice versa.
Residual Current Circuit Breakers (GFCI & ELCI) – These kinds of circuit breakers parent circuits to determine a balanced relationship between electrical currents. When that relationship is no longer balanced between the energized and neutral conductors indicates a grounded body or person has come into contact with the energized part of a circuit, preventing electrocution. It also detects current leakage in small amounts before it can cause electric shock.
To answer the previously broached questions, whether or not you have both DC and AC currents implemented on your boat determines the kind of circuit breakers you should have installed. If you have both direct and alternative current in use on your boat, you will need circuit breakers for both. All boats are created different, made up of varied components. Let your boat determine for you your Blue Seas Circuit Breaker needs.