# Logic behind Fuse Sizing for the Multiplus 3000/12/120

**URL:** <https://community.victronenergy.com/t/logic-behind-fuse-sizing-for-the-multiplus-3000-12-120/55669>\
**Category:** Q&A and troubleshooting\
**Tags:** professional, multiplus, lithium\_battery\
**Created:** [29 March 2026 11:41 UTC](https://community.victronenergy.com/t/logic-behind-fuse-sizing-for-the-multiplus-3000-12-120/55669 "2026-03-29T11:41:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![TheVanConversion](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@TheVanConversion](https://community.victronenergy.com/u/TheVanConversion)\
**Post date:** [29 March 2026 11:41 UTC](https://community.victronenergy.com/t/logic-behind-fuse-sizing-for-the-multiplus-3000-12-120/55669/1 "2026-03-29T11:41:11Z")

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Hi folks,

I’m trying to wrap my head around the logic for the fuse sizing for the Multiplus 3000/12/120.

The numbers give ~278A continuous from the battery (3000W ÷ 12V at 90% efficiency).

But Victron recommends a **400A MEGA fuse** , yet the recommended cables (~100mm²) are rated well below 400A.

I understand the fuse needs headroom above continuous draw to avoid thermal fatigue from repeated surges. But that creates a window (~280–400A) where the cable isn’t protected by the fuse against sustained overcurrent.

Is the correct interpretation that the inverter is a **self-limiting load** — it shuts down on overload before the cable is ever at risk — so the fuse is purely for **short-circuit protection** , and cable overcurrent protection is effectively delegated to the inverter’s firmware?

I just can’t understand why we don’t fuse at 300A for the continous current and then also be able to protect the cable with the fuse. **The 300A MEGA fuse should be able to ride through the surge current which lasts just a couple of seconds.**

Appreciate any insight.

Shane

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**Author:** ![Dusan](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/dusan/32/104_2.png) [@Dusan](https://community.victronenergy.com/u/Dusan)\
**Post date:** [29 March 2026 12:57 UTC](https://community.victronenergy.com/t/logic-behind-fuse-sizing-for-the-multiplus-3000-12-120/55669/2 "2026-03-29T12:57:54Z")

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Hi, I have had 2 x 200A mega fuses on each 95mm cable for over 6 years. I also have a 12/3000/120-16 inverter and it works fine.

 ![20260329_145321](https://europe1.discourse-cdn.com/victron/original/3X/a/3/a3a56202a67f18a10ffdde1f2d532b699ccb379e.jpeg)

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**Author:** ![M\_Lange](https://dub1.discourse-cdn.com/victron/user_avatar/community.victronenergy.com/m_lange/32/16_2.png) [@M\_Lange](https://community.victronenergy.com/u/M_Lange)\
**Post date:** [29 March 2026 13:11 UTC](https://community.victronenergy.com/t/logic-behind-fuse-sizing-for-the-multiplus-3000-12-120/55669/3 "2026-03-29T13:11:57Z")

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The MultiPlus has a peak power of 6000W that’s more than 500A for a few seconds.  
It can also be overloaded to 130% for around 30min if the input voltage is stable.

The fuse is a short circuit protection.