Glossary

MEGA fuse

Unit A · Also MIDI fuse, ANL fuse

What is MEGA fuse?

A bolted high-current fuse for feed cables in the hundreds of amps. It is mounted directly on studs and is one of the usual designs for the main fuse.

What matters about MEGA fuse in practice?

Besides the rating, the interrupting capacity is decisive: it must be above the short-circuit current the battery bank can deliver. With large lithium or AGM battery banks this is not always enough — there, a fuse with a higher interrupting capacity belongs at the battery.

The bolted connection needs the specified tightening torque. A loose high-current fuse creates exactly the contact resistance it is supposed to prevent.

For which currents are MEGA fuses available?

Ratings of about 40 to 500 A are common. They therefore cover the supply cables to inverter, anchor windlass, bow thruster and sub-distributions. For smaller currents there is the related MIDI format.

MEGA, ANL or Class T?

  • MEGA and ANL: bolt-down high-current fuses for most main cables.
  • Class T: very high breaking capacity, the usual choice directly at large lithium or AGM battery banks.
  • What matters is that the breaking capacity exceeds the battery’s possible short-circuit current.

How is it mounted correctly?

In a suitable holder with cover, as close as possible to the battery, tightened to the torque specified by the manufacturer. Choose the rating for the protected cable, not for the load. More on selection on the page boat fuses.

Related terms

All terms from A to Z

Still unclear?

We are happy to explain it for your specific case.

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