VALICALC · ENGINEERING WORKFLOW
DC wire selection by voltage drop
Choose a conductor area or maximum one-way cable length for a DC circuit using an explicit voltage-drop budget and wire geometry lookup.
Start this workflowWhat do I need to know first?
- DC source voltage and operating load current
- One-way cable length, copper or aluminum and conductor temperature
- Allowed drop percentage from the equipment or project specification
Goal and model boundaries
Compare DC cable length and area against a voltage-drop budget, independently of ampacity.
- Two current-carrying conductors of the same size and material are included.
- Connector/contact losses, ampacity and protection need separate checks.
Set a DC drop budget
Read the equipment voltage tolerance and operating current.
Allowed drop = source voltage × target percent / 100.
- Expected output
- An explicit voltage budget and design current.
- Next step
- Use Minimum Conductor Size mode for the measured cable run.
Solve the wire or cable run
Select DC and Minimum Conductor Size or Maximum Cable Length mode.
The same resistive drop equation is solved in reverse; standard sizes are rounded upward where provided.
- Expected output
- A voltage-drop-limited area or length, plus the achieved drop.
- Next step
- Look up the proposed gauge and then perform the independent installation review.
Check size and resistance
Compare the selected area with AWG or metric geometry.
Temperature-adjusted resistance increases as metal temperature rises.
- Expected output
- A documented size and resistance assumption.
- Next step
- Check connector loss, fault protection and ampacity with qualified project data.
Units and context
- Use metres or feet for one-way length; the engine includes the return conductor.
- Supply volts and target percent are different inputs. A 3% budget at 12 V is only 0.36 V.
Common mistakes to avoid
- Doubling a one-way length twice
- Assuming a low drop proves thermal suitability
- Using room temperature when conductor temperature is substantially higher
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