AGC fuse (glass tube, 1/4" × 1-1/4")
The AGC is the standard American glass tube fuse. It is 6.35 mm (¼") in diameter and 31.75 mm (1¼") long. It is found in electronics, older appliances, and panel fuse holders throughout North America.
Specifications
| Property | Value |
|---|---|
| Standard designation | AGC (UL 248-14) |
| Body diameter | 6.35 mm (¼ in) |
| Overall length | 31.75 mm (1¼ in) |
| Body material | Glass |
| End caps | Nickel-plated brass |
| Voltage rating | Up to 250 V AC |
| Amperage range | 1/16 A to 30 A (common) |
Fast-blow vs slow-blow
| Type | Code suffix | Behavior | Use case |
|---|---|---|---|
| Fast-blow | AGC or AG | Opens almost instantly at rated current | Sensitive electronics, signal circuits |
| Slow-blow (time-delay) | AGS or MDL | Handles brief inrush current before opening | Motors, transformers, devices with startup surges |
Fast-blow and slow-blow fuses of the same amperage rating are not interchangeable. A slow-blow in a fast-blow circuit may not protect adequately against faults. A fast-blow in a slow-blow circuit will trip on normal startup currents.
Common applications
- Consumer electronics (amplifiers, power supplies, turntables)
- Older US appliances and panel fuse holders
- Test and measurement equipment
- Power strips with replaceable fuses (usually in the IEC 320 inlet)
How to read the markings
The amperage and voltage rating are printed on one or both end caps. Common formats: "5A 250V", "5 Amp", or "5A T" where T denotes time-delay/slow-blow. The wire element is visible through the glass body — a broken element confirms the fuse has blown.
Holder compatibility
AGC fuses fit panel-mount fuse holders, in-line fuse holders, and fuse clips designed for the ¼" × 1¼" form factor. The European equivalent (IEC 60127) fuse is 5 × 20 mm and is not compatible with AGC holders — both diameter and length differ.
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