| Ampere Interrupting Capacity (AIC)
| A fuse rating that establishes the level of fault current it can interrupt. In an application, a fuse must be able to sustain the application’s largest potential short circuit current. |
| Ampere Rating
| A rating of a fuse’s continuous current-carrying capability. |
| Arc
| The effect generated when electrical current bridges the air gap between two conductors that are not touching. |
| Break Distance
| The point at which the arc is extinguished. |
| Circuit Breaker
| An electrical safety device. When the current passing through it exceeds a certain amperage, the breaker trips, breaking the circuit. |
| Clearing Time
| The amount of time a fuse takes to blow. This amount of time is inversely related to the level of overcurrent. |
| Current Limiting Fuse
| A type of fuse that incorporates features or dimensions for the rejection of another fuse of the same ampere rating, but with a lower interruption rating. |
| Double Throw
| A safety switch type that switches two loads or power supplies. |
| Dual Horsepower Rating
| A safety switch rating of its standard and maximum horsepower ratings. |
| Element
| The part of a fuse that melts to break the circuit. Typically, it is a thin strip of metal. |
| End Blade
| A type of cartridge fuse where the terminals resemble blades. It is meant to be installed by sliding the blade terminals into slots. |
| Fault Current
| The current that may flow in any part of a circuit under specific abnormal conditions. |
| Ferrule
| Another name for end blades. |
| Fuse
| An electrical safety device. When the current passing through it exceeds a certain amperage, the element melts, breaking the circuit. |
| Fusible
| Capable of being fused or melted by heat. A fusible safety switch uses a fuse. |
| General Duty Safety Switch
| A safety switch used primarily for residential or light commercial applications. |
| Heavy Duty Safety Switch
| A safety switch used primarily for commercial and industrial applications. |
| Knife Blade
| The hinged movable contact in a safety switch that actually makes and breaks the circuit. So named for its shape. |
| National Electrical Code
| Abbreviated NEC. Regulations governing construction and installation of electrical wiring and components. |
| NEMA
| Abbreviation for National Electrical Manufacturers Association. An organization of manufacturers of electrical products. |
| Non-Fusible
| Not capable of being fused or melted by heat. A non-fusible safety switch does not use a fuse. |
| Nontime-Delay Fuse
| A fuse type used in applications where high inrush currents do not occur. It is designed to blow as quickly as possible. |
| Overload (or Overcurrent)
| A condition in which current is in excess of the normal load being drawn. |
| Pole
| Refers to the number of wires that the switch disconnects at one time. |
| Safety Switch
| A device used to open and close a circuit. |
| Service Entrance
| The point at which electricity enters a building. |
| Short Circuit
| An electrical fault created when two exposed conductors touch. |
| Single Throw
| A safety switch type that switches one load. |
| Solid Neutral
| Abbreviated S/N. A solid metal bar mounted within the safety switch enclosure, designed to accept incoming and outgoing neutral conductors. No current flows through it. |
| Time-Delay Fuse
| Fuse type designed primarily for use in circuits containing motor loads. It has a time-delayed element to keep it from blowing under high inrush currents. |
| Underwriters’ Laboratory
| Abbreviated UL. An independent laboratory that tests equipment to determine whether it meets certain safety standards when properly used. |
| Voltage Rating
| A fuse rating for the level voltage it can handle. The voltage rating of a fuse must be at least equal to the circuit voltage. It can be higher than the circuit voltage, but never lower. |
