Example field question
Use this calculator when a design review or site issue requires a quick engineering check before a detailed manufacturer selection.
VoltCheck24 Engineering Calculator
DC Wire Size Calculator
Use this DC wire size calculator to estimate voltage drop and compare AWG or mm2 conductor sizes from load current, one-way cable length, and system voltage.
How to use this calculator
- Collect the values below from the equipment nameplate, data sheet, or field measurement.
- Enter values using one consistent unit system and use worst-case operating conditions.
- Review the result, margin, and engineering note before selecting hardware.
- Cross-check the result with the related calculator and save the review for your project record.
Input checklist
- System voltage: 12V, 24V, 48V, or custom
- Load current and startup current
- One-way cable distance
- Allowable voltage-drop percentage
Common mistakes to avoid
Do not mix nominal values with measured worst-case values. Keep units consistent and include cable, temperature, duty, and derating assumptions where applicable.
Standards and validation
Review the result against local codes, IEC/NEC/NFPA/ISO practices when applicable, project specifications, and the latest manufacturer data sheet.
Formula and Inputs
DC voltage drop is estimated from load current multiplied by round-trip conductor resistance, then compared with the allowable voltage-drop percentage.
Industrial Use Cases
Use this DC wire size calculator for control circuits, battery wiring, LED strips, 12V and 24V equipment, solar DC runs, and low-voltage field devices. Enter one-way cable distance; the tool accounts for the outgoing and return conductors.
Engineering Note
Use the actual one-way cable length, conductor material, installation temperature, and local electrical code. Final conductor ampacity and protection must be verified from current standards and manufacturer data.
DC wire sizing workflow for global projects
DC wiring problems usually start with a simple question: will the load still receive enough voltage after current flows through a long conductor? VoltCheck24 treats wire size as a voltage-drop and verification workflow, not only a gauge lookup. Start with the real load current, one-way route length, system voltage, and acceptable voltage drop. Then compare the result with ampacity, fuse or breaker size, terminal limits, insulation temperature, and local code requirements.
DC source+Supply conductor resistance+Load current=Terminal voltage margin
| Use case | Common search intent | What to verify after voltage drop |
|---|---|---|
| 12V battery, RV, marine, LED | 12V wire size calculator, battery cable size | Fuse location, flame rating, vibration, wet or outdoor environment |
| 24V PLC, sensor, solenoid, IO-Link | 24V cable calculator, sensor voltage drop | Device minimum voltage, inrush current, shared returns, SMPS tolerance |
| Solar DC and off-grid wiring | solar DC cable size calculator, PV voltage drop | UV rating, connector current, temperature derating, PV code rules |
| International panel wiring | AWG to mm2, wire size calculator DC | AWG/mm2 conversion, terminal range, IEC or NEC project standard |
Important: voltage-drop calculators support preliminary sizing only. Final conductor selection must be checked against the latest local electrical code, manufacturer data sheets, protection coordination, and measured field conditions.
Generic DC wire sizing
Use this page when the main decision is conductor area. Start with current, one-way distance, voltage, and a target drop, then compare the result with ampacity and protection.
Worked field question: Example: a 24V, 1.2A field device 80m from the panel. Record the route, return path, ambient temperature, and terminal range before selecting a cable.
FAQ
What size wire do I need for DC?
Start from load current, one-way cable length, system voltage, allowable voltage drop, and conductor material. The calculator estimates voltage drop and helps choose the next practical AWG or mm2 size.
Should I enter one-way or round-trip cable length?
Enter the one-way cable distance when the calculator states that loop resistance is calculated internally. If a tool asks for loop length directly, use the full out-and-back distance.
What voltage drop is acceptable for DC wiring?
Many preliminary designs use about 3% for sensitive loads and up to 5% for less critical loads, but the final limit must follow the project specification and applicable code.
Preliminary engineering reference only. Confirm final selections against current standards, project specifications, and manufacturer data.