Blue Sea Systems Class T Fuse 300A 125V DC

The Blue Sea Systems Class T Fuse is built for the high fault currents found on inverter feeds and large lithium-ion or TPPL battery banks. At 300A and 125V DC maximum, it delivers a 20,000A interrupt rating and an extremely fast short-circuit response — the reason most inverter manufacturers specify Class T protection ahead of their equipment.

Key features

• 300A rating, 125V DC maximum
• 20,000A interrupt capacity (AIC)
• Extremely fast short-circuit trip response
• UL listed to standard 248-15

This fuse mounts in a Class T Fuse Block with an insulating cover, sized for either the 110-200A or the 225-400A block depending on amperage. It's typically installed as close to the battery bank as practical on the positive feed to an inverter, DC-DC charger, or other high-current load.

Because Class T fuses are UL listed and carry such a high interrupt rating, they're the usual choice when a system's short-circuit current could exceed what an ANL or MRBF fuse is rated to safely clear — most commonly on lithium battery banks capable of very high discharge currents.

Torque the stud connection to spec when landing the cable lug — an under-torqued connection at this amperage can generate enough resistive heating to nuisance-trip the fuse or damage the block over time. If you're sizing a Class T fuse for a new inverter install, check the inverter manufacturer's recommended main fuse rating first, since it usually calls for a specific Class T amperage rather than leaving it to a general wire-gauge calculation. Keep spares on hand at your working amperage since a blown fuse must be replaced, not reset.