Panel-to-Panel Cable Check
Derated ampacity + voltage-drop check (XLPE Cu 4C×95) for this run — both must pass.
Sub-panel feeders accumulate breaker upgrades until the cable is the weakest link. Verify the run against the upstream breaker's new rating — protection must protect the cable, not just the load.
Two checks, both must pass: thermal ampacity (derated) and voltage drop (≤3% for feeders is the common design norm). Long runs usually fail on voltage drop first — the cable that carries the current still can't deliver the volts.
Planning estimate only — interconnection, protection settings and compliance must be reviewed and signed off by a licensed electrical engineer and your utility before energisation.
Use the free Panel-to-Panel Cable Check online — Derated ampacity + voltage-drop check (XLPE Cu 4C×95) for this run — both must pass. Runs instantly in your browser: no signup, no upload, mobile-friendly.
About Panel-to-Panel Cable Check
Sub-panel feeders accumulate breaker upgrades until the cable is the weakest link. Verify the run against the upstream breaker's new rating — protection must protect the cable, not just the load.
How to use Panel-to-Panel Cable Check
- 1Pick the cable/conductor and enter the load and run length.
- 2Set an honest derating factor.
- 3Read utilization, voltage drop and the combined verdict.
Why use Panel-to-Panel Cable Check?
- ✓Two checks in one: derated ampacity AND voltage drop — both must pass
- ✓Real cable data for common Indian sizes and overhead conductors
- ✓Derating slider for grouping, soil and temperature reality
- ✓3% drop norm enforced with the verdict logic
Frequently asked questions
How do I check if a cable can carry my load?+
Two gates: load current (kW ÷ (1.732 × 415 × PF) for three-phase) must stay under the DERATED ampacity, and voltage drop (mV/A/m × current × length) must stay within ~3%. Long runs usually fail on drop while passing ampacity — this tool runs both gates.
Why derate cable ampacity from the catalogue value?+
Catalogue ratings assume one cable, standard soil/air at reference temperature. Reality groups cables in trays, buries them in hot dry soil, and runs Indian summers — each factor multiplies capacity down. 0.8–0.85 combined is a routine honest derating; ignoring it is how 'rated' cables run hot for years.
What voltage drop is acceptable?+
Common design norms: ≤3% for feeders, ≤5% total to the farthest load. Beyond that, motors start poorly and burn out faster, and every percent of drop is I²R energy you buy without using. For revenue circuits (solar plants), designers target 1–2% — lost volts are lost billing.
The cable passes ampacity but fails voltage drop — now what?+
Upsize for the run, not the load: friction... resistance falls with conductor area, so one size up typically halves the drop. Alternatives: shorten the route, raise the distribution voltage for the trunk, or move the load's supply point. Never 'fix' drop by ignoring it — the symptom bills monthly.
Embed Panel-to-Panel Cable Check on your website
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<iframe src="https://tooljolt.com/tools/panel-to-panel-cable-calculator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Panel-to-Panel Cable Check — ToolJolt" loading="lazy"></iframe>Related Energy tools
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