
Mersen Fuses

Mersen Class J time-delay fuses provide IEC Type 2 “no damage” protection to main, feeder and branch circuits, as well as protection for motor and transformer inrush currents. They are available with SmartSpot visual open fuse indicator.
Mersen Class L fuses are 20 percent more current limiting than any other Class L fuse on the market. The A4BQ fuses protect service entrance equipment and protect downstream circuit components against short-circuit let-thru current. A4BQ fuses’ built-in 4-second time-delay (at 500 percent of rated current) accommodates harmless in-rush currents with no nuisance opening. The A4BT fuses protect mains, feeders and general circuits. The 10-second time-delay (at 500 percent fuse rating) is ideal for large motors and other loads with high in-rush currents.
Mersen Class K5 general purpose fuses provide low cost protection for feeder and branch circuits serving heating, lighting and other non-motor loads. They will safely interrupt available short-circuit currents up to 50,000 amperes in all ratings.
Mersen Class RK1 time-delay fuses provide IEC Type 2 “no damage” protection to mains, feeder and branch circuits serving motor and non-motor loads. They will open fast enough under extreme fault conditions for short-circuit protection to prevent damage to switches, motor starters and other circuit components, while still providing the time-delay needed for motor in-rush currents.
Mersen Class RK5 current-limiting time-delay fuses provide overcurrent protection for service entrance equipment, feeders, branch-circuits, motors and transformers. The time-delay safely handles harmless in-rush currents.
Products
Fuses are safety devices that are intended to provide protection to both equipment and people in the event of a power surge or an overcurrent situation. A fuse can provide this protection by using a small piece of wire that is sacrificial, and is intended to burn up when too much current is passed through it. When this happens, the fuse eliminates the flow of electricity in that circuit until it is replaced. The size and type of wire that is used in the fuse will dictate how much current can pass through that individual fuse. So the main thing to remember is, when a fuse blows, it must be replaced and cannot be reused.
Circuit breakers are intended to be reused after they are “tripped” during a power surge or an overcurrent situation. Much like fuses, circuit breakers are designed to trip at a certain current level. This is intended to protect both equipment and anyone in the area of that particular circuit. Circuit breakers can be found in just about any variation from single phase, low current applications to three phase, and high current applications.
As a general rule: fuses are more simplistic and reliable. They cost less initially and are better suited for individual circuit protection. However, they can create more cost over time with each use and may create hazards due to the exposed connection points. Whereas circuit breakers offer better branch circuit protection and do not need to be replaced after each use. They are more expensive initially and, because of their complexity, are more prone to failure over time.