Calculator Inputs
Example Data Table
| Input | Example Value | Meaning |
|---|---|---|
| Source voltage | 24 V | Supply voltage applied to the series chain. |
| Series loads | 4 Ω, 6 Ω, 2 Ω | Resistance values connected end to end. |
| Wire length | 10 m | Total conductor length in the circuit path. |
| Wire area | 2.5 mm² | Cross-sectional area of the conductor. |
| Internal resistance | 0.1 Ω | Resistance inside the source or supply path. |
Formula Used
Total resistance is found by adding every series resistance.
Rtotal = R1 + R2 + R3 + Rwire + Rinternal + Rcontacts + Rextras
Current is calculated with Ohm’s law when source voltage is known.
I = Vsource / Rtotal
Voltage drop across each item uses the same series current.
Vdrop = I × Ritem
Power loss or load power is calculated by current squared times resistance.
P = I² × R
Wire resistance is temperature corrected.
Rwire = ρ × L ÷ A × [1 + α × (Toperating − Tbase)]
How to Use This Calculator
Choose whether you know the source voltage or the circuit current.
Enter supply data, wire data, temperature data, and limits.
Add every load in the same order as the real series circuit.
Use contact resistance for terminals, connectors, switches, or joints.
Press calculate. The result appears above the form.
Review voltage drop, load power, wire loss, and efficiency.
Use CSV for spreadsheets. Use PDF for printable reports.
Series Voltage Drop Guide
Why Series Voltage Drop Matters
A series circuit has one current path. The same current passes through every load. Each resistance takes part of the supply voltage. The division depends on resistance. A larger resistance gets a larger voltage drop. This makes series circuits simple to model, but it also makes poor connections important. One weak joint can reduce the voltage available to every load.
What This Tool Checks
This calculator estimates current, total resistance, load voltage, wire voltage, and power. It also includes source resistance, extra series resistance, and contact resistance. These values are useful in practical wiring. Real circuits are not ideal. Wire has resistance. Terminals have small losses. A supply may have internal resistance.
Wire and Temperature Effects
Conductor resistance changes with material, length, area, and temperature. A long wire increases voltage loss. A small wire area also raises loss. Heat usually increases metal resistance. The tool applies a temperature correction factor. This helps when the circuit works in warm panels, machines, vehicles, or outdoor cabinets.
Power and Design Margin
Power is important because heat follows power loss. A resistor, wire, switch, or contact must handle its wattage safely. The calculator compares load power with your selected limit. It also compares loss voltage with your selected drop percentage. These checks do not replace a code review, but they help you find weak points early.
Reading the Result
The load voltage is the useful voltage across the series components. Loss voltage is the part spent in wire, source resistance, contacts, and extra resistance. Efficiency shows how much supply power reaches the loads. A low value means too much energy is becoming heat. Reduce length, increase wire area, improve contacts, or lower current when needed.
Practical Use
Use this calculator during design, testing, troubleshooting, and report preparation. Enter measured resistances when possible. Use conservative values when data is uncertain. Check the hottest expected operating temperature. Then export the result for records. Good records make later maintenance easier and safer.
FAQs
1. What is voltage drop in a series circuit?
It is the voltage used across each series resistance. The drops add together and equal the applied source voltage, including wiring and internal losses.
2. Does every series component get the same voltage?
No. Every component gets the same current. Voltage divides according to resistance. Higher resistance creates a higher voltage drop.
3. Why add wire resistance?
Wire resistance can reduce load voltage. It also creates heat. Long wires and small conductors can make this effect large.
4. What is contact resistance?
Contact resistance is the small resistance at terminals, switches, connectors, and joints. It can matter in high current circuits.
5. How is power calculated?
Power is calculated as current squared times resistance. The same formula works for loads, wires, and internal resistance.
6. What does efficiency mean here?
Efficiency compares useful load power with total supply power. Higher efficiency means less energy is lost in wires and unwanted resistance.
7. Can I use known current instead of source voltage?
Yes. Select known current mode. The calculator then finds the required source voltage for the entered total resistance.
8. Is this suitable for final electrical approval?
It helps with estimation and design review. Final approval should follow local codes, equipment ratings, and qualified engineering judgment.