Glass Tube Fuses, Fast and Time-Delay Types
Glass tube fuses are replaceable, one-shot overcurrent components with a visible glass body and metal end caps or axial leads. This collection focuses on small cartridge formats, especially 3.6 × 10 mm, 5 × 20 mm and 6 × 30 mm, with fast-acting (F) and time-delay (T) current options, assorted packs and compatible holders. A glass body makes the element visible; it does not establish a fuse's fault-interrupting capacity or make differently rated parts interchangeable.
Choose the physical form first
- Cartridge fuses: end-cap tube versions are intended for the correctly sized clips or holder. Listings include common 5 × 20 mm and 6 × 30 mm formats and smaller 3.6 × 10 mm versions. Nominal dimensions, contact style and actual mounting clearance should match the equipment.
- Axial-lead glass fuses: pin or wire-lead versions are intended for suitable PCB mounting. Verify body dimensions, lead spacing, lead geometry and specified soldering limits; a leaded fuse cannot simply be substituted for a clip-in cartridge.
- Single-rating and assortment packs: some selections are F0.1A, F1A, T500mA, T3.15A or other exact current/speed options; other listings bundle several values. Pack labels from 5 to 200 pieces occur in the assortment. Confirm whether the selected option is a mixed set or one rating repeated.
- Fuse holders and clips: BLX-A, BF-012, screw-cap, inline wire and PCB socket listings belong here as accessories. Check 5 × 20 mm versus 6 × 30 mm compatibility, contact/current/voltage rating, panel or board dimensions, wire gauge and whether a fuse is included. The holder alone does not interrupt a fault.
Fast-blow versus slow-blow
Fast-acting F fuses and time-delay T fuses have different time-current behavior. A time-delay device can withstand a specified short inrush event, while a fast-acting part may open sooner under a comparable overload. This difference is defined by the exact component's characteristic and test conditions, not by glass appearance. A printed 5 A on two fuses does not mean they open at the same time or can be swapped in the same equipment. For replacement, use the specified current, response, dimensions, voltage, interrupting rating and manufacturer's part, not merely the same amperage.
Selection sequence
- Identify the original fuse or circuit requirement. Record normal current, startup or inrush profile, supply voltage and whether the circuit is AC or DC; determine the available prospective fault current.
- Match the fuse's rated current and documented F/T or other time-current characteristic to the equipment specification. If the original marking cannot be identified, do not guess from the appliance type.
- Verify the voltage rating and breaking capacity for the specific AC or DC application. “250 V” on a seller title alone cannot confirm safe interruption of a particular fault current, and a glass tube is not inherently high- or low-breaking-capacity without the part documentation.
- Confirm 3.6 × 10, 5 × 20 or 6 × 30 mm body dimensions, end cap or lead format, holder contact condition, ambient temperature and installation fit. A near-matching length can still make unreliable contact.
- Choose the exact variant and quantity. Some shared listings combine size, F/T response, amperage and 10/20/30/50/100-piece pack options; select each attribute rather than relying on an expansive title.
Use and safety boundaries
A fuse is a one-time protective device, not a resettable circuit breaker, thermal switch, surge protector or proof that a damaged circuit is safe. Do not bypass or up-rate a fuse to stop repeated opening. A ceramic fuse with the same dimensions may have a different breaking capacity and construction; do not equate ceramic and glass solely by size, or infer approval from generic seller labels. For mains-powered equipment, fault diagnosis and replacement should follow the device service specification and qualified electrical practice. No universal wiring instructions are provided for these products.
Buying checklist
Keep the full original marking or manufacturer part number, current in A or mA, F/T response, voltage with AC/DC context, interrupting capacity, body size, end-cap or axial lead format, expected fault conditions, required holder rating, selected pack quantity and traceable approval evidence if required. Verify all claims for the exact selected part.
Frequently asked questions
Can I use a T2A fuse instead of an F2A fuse?
Not without circuit and manufacturer approval. Equal current marking does not mean equal opening behavior during overload or inrush.
Does a 5 × 20 mm 250 V fuse fit every 5 × 20 mm holder?
Physical size may match, but the holder's contact, current, voltage and mounting ratings must also suit the application.
Is a transparent glass fuse suitable for high-fault-current circuits?
Transparency proves nothing about interrupting capacity. Check the exact fuse's documented breaking rating against the circuit.
Does a mixed kit contain every value shown in its title?
Not necessarily. Read its selected size, speed and package contents before ordering.
