Junction box size calculator
Use our junction box size calculator to calculate accurate size and measurement values instantly.
Calculator
Estimate feeder current from total load and voltage, then apply 125% sizing factor.
Formula: Current = P/V (single phase) or P/(sqrt(3)V) (3-phase); panel size approx = 1.25 x current
What each field means
- Total Load (kW): Enter a valid value for this field.
- Voltage (V): Enter a valid value for this field.
- System Phase: Enter a valid value for this field.
Estimated Panel/Fuse Rating (A)
Your result will appear here.
About Junction box size calculator
The Junction box size calculator helps you estimate cable and electrical values quickly using consistent assumptions and practical calculation rules.
Formula Explanation
Current = P/V (single phase) or P/(sqrt(3)V) (3-phase); panel size approx = 1.25 x current
Inputs You Need
- Required measurement values relevant to this calculator
- Unit selection: Total Load (kW), Voltage (V), System Phase
- Optional tolerance, safety, or scenario values if applicable
Step-by-Step Usage
- Enter your known values in the calculator fields.
- Select units and options that match your scenario.
- Click Calculate to generate your output.
- Copy, save, or share the result for later reference.
Example
Run the tool with realistic values from your use case and compare the output against expected ranges for cable and electrical calculations.
Frequently Asked Questions
Is this Junction box size calculator accurate?
Yes, when correct inputs and units are provided.
Which units does this calculator support?
This tool is optimized for Total Load (kW), Voltage (V), System Phase.
Can I use this calculator on mobile?
Yes, the form is optimized for touch inputs and smaller screens.