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Interactive calculator

Fuse sizing calculator

Estimate a standard fuse size and visualise how normal current compares with the selected protection rating.

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1Tell us what you knowUse the simple fields first.
2See the recommendationSolarLab explains what the number means.
3Refine or downloadContinue only when the result makes sense.

Inputs

i
Battery and PV circuits are normally DC. AC output circuits use AC-rated protection.
i
Voltage the fuse must safely interrupt. Example: 51.2 V nominal for a 48 V-class LiFePO4 battery bank, or a higher-voltage PV string.
i
Expected normal current through the fuse. Example: 60 A.
i
Margin above normal current. Example: 125% means the fuse is sized at 1.25 times normal current.
Visual aid

Fuse loading visual

The coloured fill represents normal operating current as a percentage of the selected standard fuse rating.

Example

Example calculation

SolarLab uses the current project values to show how the recommendation changes.

Common mistake

Do not rely on one number alone

Check the result against actual equipment and site conditions.

Frequently asked

Is this installation-ready?

No. It is a planning estimate that should be verified by qualified professionals.

How was this calculated?

Calculation method

Formula

The calculator uses the displayed inputs and standard planning relationships.

Important assumptions

Verify the final design against actual equipment data sheets, site conditions, and applicable requirements.

Read the full methodology and update history →
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