4 Pack, 15A Type S Plug Fuse, Non Tamp, Time Delay Fustat,Boxed. Size rejection feature helps to prevent overfusing. Heavy duty dual-element construction. Superior overload and short-circuit protection. From theManufacturer Heavy-Duty Type S fuse for critical circuit protection. Used forair conditioners, furnace blower motors, swimming pool pumps, deep freezers orany circuit where motors frequently turn on and off. Used for all commercialapplications, the Type S rejection base plug fuse is an industrial strengthproduct. It provides superior protection, yet will not open under repeatedmotor startups. Available in a wide amp range to permit exact sizing for motorprotection. The rejection base threads prevent a larger amp fuse from beingused. Example: A 30 amp fuse cannot be installed in a 20 amp receptaclebecause of the different sized threads. Heavy-duty fuse. These fuses threadinto fuse receptacles. Threaded fuse type: Rejection Base (porcelain threads).Not interchangeable with Edison Base (brass threads) type. Heavy-duty (S)category plug fuse. The heavy-duty fuse (S) is an industrial strength productfeaturing the exclusive Cooper Bussmann dual-element construction. This springloaded design provides superior short-circuit and overload protection. The Sfuse has more time-delay than the medium-duty fuses in order to better protectmotors and critical residential circuits. Plug fuses are rated for a maximumof 125Vac. Plug fuses are often used in residential and industrial branchcircuit and motor protection. Fuses are used to protect furnace blower motors,pumps, power tools, garage door openers, etc. Motor protection fuses areusually used in conjunction with branch circuit protection. The fuse is oftenlocated in a box cover unit. Plug fuses provide a compact and inexpensivemethod to prevent damage to electrical motors. They help reduce downtime andlower maintenance costs by opening the circuit when a dangerous overload ispresent. When used for residential branch circuit protection, fuses aretypically located in the main fuse panel.