Formula Used
Temperature adjusted resistivity: ρT = ρ20 × [1 + α × (T - 20)]
Single conductor resistance: R = ρT × L ÷ A
Parallel group resistance: Rgroup = Rsingle ÷ number of identical runs
Equivalent resistance: Req = 1 ÷ Σ(1 ÷ Rgroup)
Current sharing: Ipath = Itotal × [(1 ÷ Rpath) ÷ Σ(1 ÷ Rpath)]
Voltage drop: Vdrop = Itotal × Req
Power loss: Ploss = Itotal² × Req
Current density: J = current per run ÷ conductor area
How To Use This Calculator
- Enter the total load current and source voltage.
- Add each conductor path with length, area, material, and temperature.
- Use runs when one path contains identical parallel conductors.
- Select Custom when entering your own resistivity and coefficient.
- Set limits for voltage drop and current density.
- Press Calculate to show results below the header.
- Use CSV or PDF buttons to save the report.
Example Data Table
| Path |
Material |
Runs |
Length |
Area |
Temperature |
| Conductor A |
Copper |
1 |
25 m |
35 mm² |
75°C |
| Conductor B |
Copper |
1 |
25 m |
35 mm² |
75°C |
| Conductor C |
Copper |
1 |
25 m |
35 mm² |
75°C |
Parallel Conductor Planning Guide
Parallel conductors are used when one conductor is not enough for a load. They divide current between two or more paths. The sharing is not always equal. Resistance controls the current in each path. A lower resistance path carries more current. This calculator compares those paths before installation or review.
Why Resistance Matters
Resistance depends on material, length, area, and temperature. Copper has lower resistance than aluminum. A longer conductor has higher resistance. A larger area lowers resistance. Temperature also changes resistance. Most metallic conductors increase resistance as they become hotter. This tool adjusts resistivity by temperature before finding each path resistance.
Current Sharing
Current flows through parallel paths by conductance. A path with higher conductance receives more current. Matched conductors share current better. Unequal lengths, sizes, materials, or terminals can cause imbalance. Imbalance can overload one conductor while the total load seems acceptable. The calculator shows group current, current per run, and density.
Voltage Drop And Loss
Voltage drop is important for performance. High drop can reduce equipment output. It can also increase heating. Power loss is found from current squared times equivalent resistance. That loss becomes heat in the conductors. Lower resistance reduces wasted energy. The selected voltage drop limit helps judge whether the design needs larger or shorter conductors.
Practical Use
Use the result as an engineering estimate. Confirm final conductor sizing with applicable codes, installation rules, terminal ratings, and safety standards. Real installations include connection resistance, conduit grouping, ambient temperature, insulation limits, and protective device settings. For best sharing, use conductors with the same material, size, length, route, and termination method. Always let a qualified professional review critical electrical work.
FAQs
What does a parallel conductor calculator do?
It estimates equivalent resistance, current sharing, voltage drop, power loss, and current density for multiple conductor paths connected in parallel.
Why do parallel conductors not always share current equally?
Current sharing depends on resistance. Shorter, larger, cooler, or lower resistance conductors carry more current than higher resistance paths.
Can I mix copper and aluminum conductors?
The calculator can compare mixed materials. Actual installations must follow local electrical codes, terminal ratings, and approved connection methods.
What is current density?
Current density is current per conductor divided by conductor area. It helps compare loading stress across different conductor sizes.
Why does temperature affect the result?
Conductor resistance changes with temperature. Most common metals have higher resistance at higher operating temperatures.
What does voltage drop percent mean?
It is voltage drop divided by source voltage, then multiplied by one hundred. Lower values usually mean better delivery performance.
What is equivalent resistance?
Equivalent resistance is the single resistance value that represents all active parallel conductor paths combined.
Can this replace professional electrical design?
No. It provides estimates only. Final work should follow applicable standards and be checked by a qualified electrical professional.