| Ampere Interrupting Capacity (AIC)
| Also “Interrupting Rating.” A rating of the amount of current that a protective device, such as a fuse or circuit breaker, can safely interrupt. |
| Ampere Rating
| A rating of the amount of current a protective device will carry continuously without deteriorating or exceeding temperature rise limits. |
| Arc
| The effect generated when electrical current bridges the air gap between two conductors that are not touching. |
| Arc Fault
| An arc fault is an electrical fault characterized by low and erratic current that might ignite combustible materials. |
| Bolt-On
| A type of circuit breaker that is bolted into place. Generally found in commercial and industrial applications. |
| Branch Circuit
| A circuit that supplies power to the electrical loads in a building and is terminated at a distribution device (panelboard, loadcenter, etc.). |
| Cable-In/Cable-Out
| A circuit breaker mounting method in which the line-side and load-side terminal electrical connections are made by cable. Method used in industrial applications. |
| Circuit Breaker
| An overcurrent protection device. After tripping to break the circuit, it can be reset to protect the circuit again. |
| Current Limiting
| A type of supplementary protector which limits the amount of damaging short circuit current. |
| DIN-Rail
| A solidly mounted, rail-type device to which any number of circuit breakers can be mounted. |
| Double Pole
| Term used to describe a breaker that draws power from two poles of a loadcenter or similar device. Double pole means that it disconnects two wires. |
| Duplex Circuit Breaker
| A specialized overcurrent protection device designed to allow two poles to fit in a standard one-pole space. Can only be installed in loadcenters equipped with notched stabs. |
| Frame
| A component of a miniature circuit breaker. Its primary function is to provide a rigid, mechanically strong, insulated housing in which the other components are mounted. |
| Front-Connected
| A circuit breaker mounting method by which a circuit breaker can be rigidly mounted to a panel from the front. Mounting bolts are usually used to hold the circuit breaker in place. |
| Hydraulic Magnetic
| A miniature circuit breaker technology often used in special applications. It is independent of the ambient temperature, and especially tolerant of vibration and impact. |
| IEC
| Abbreviation for International Electro-technical Commission. This organization is associated with equipment used internationally. |
| Individual Mounting Base
| A circuit breaker mounting method which provides a way to rigidly mount individual circuit breakers using a rear-mounted circuit breaker clip or other device. |
| Interrupting Rating
| Also “Ampere Interrupting Capacity (AIC).” A rating of the amount of current that a protective device, such as a fuse or circuit breaker, can safely interrupt. |
| Let-Through Current
| The limited amounted of short circuit current let-through by a current limiting supplementary protector. |
| Loadcenter
| A wall mounted device that delivers electricity from a supply source to loads in light commercial or residential applications. |
| Miniature Circuit Breaker
| Also “Branch Circuit Breaker.” Used to switch and protect the lowest common distribution voltage in an electrical system. Generally used in a loadcenter, panelboard, or similar device. |
| NEC
| Abbreviation for National Electrical Code. A set of electrical installation standards published by the National Fire Protection Agency. The NEC is the most widely adopted electrical code in the United States. |
| Operating Mechanism
| A component of a miniature circuit breaker. Its function is to provide the means of opening and closing the circuit. |
| Overcurrent Protective Device
| A device such as a circuit breaker or fuse. In the event of an overcurrent, this device will quickly terminate power to the circuit. |
| Overcurrent
| A current higher than the current a conductor or electrical component can safely carry. |
| Overload
| A temperature buildup caused by excessive loads on a circuit, causing damage to the conductor’s insulation. |
| Panelboard
| A wall mounted device that delivers electricity from a supply source to loads in light commercial, commercial and industrial applications. |
| Plug-In
| A type of circuit breaker that is literally plugged into the bus bar stabs. Generally found in residential applications. |
| Pole
| Refers to the number of conductors or wires that the circuit breaker disconnects at one time. |
| Short Circuit
| An electrical fault that is created when two exposed conductors touch or when conductor insulation fails. |
| Single Pole
| Term used to describe a breaker that draws power from one pole of a loadcenter or similar device. Single pole means that it disconnects one wire. |
| Supplementary Protector
| A device similar in function to a miniature circuit breaker, but not UL approved as a circuit breaker. Used in conjunction with circuit breakers. |
| Thermal Magnetic
| The predominant trip unit technology used in the United States market. A bimetal and an electromagnet work together to provide overload and short circuit protection. |
| Trip Unit
| A component of a miniature circuit breaker. It is the brain of the miniature circuit breaker. It activates the operating mechanism in the event of a prolonged overload or short circuit. |
| UL
| Underwriters Laboratory. An independent laboratory that test equipment to determine whether it meets certain safety standards when properly used. |
| Voltage Rating
| A rating of the voltage at which a piece of equipment is designed to operate. |
| Zero Point
| Also “Current Zero.” A point in the AC current sine wave where the value is zero. |
| Zero Point Construction
| A term given to a circuit breaker constructed to extinguish an arc after a half cycle, or as soon as the current passes through zero point the next time. |
