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Power (Ohm’s Law & voltage drop)
Electrical tool — Power step: one grid for Ohm’s Law, BTU/hr, and voltage drop.
Last two inputs
- The last two of Voltage, Current, Resistance, Power (W), or BTU/hr that you type are the inputs.
- Every other field that those two values can determine updates live and highlights.
- Power (W) and BTU/hr are the same quantity (1 W ≈ 3.412 BTU/hr). Typing both only converts; it does not invent V, I, or R.
- Length, phase, and material do not steal those two roles — they only refresh voltage drop.
Voltage drop
- Needs Voltage, Current, and one-way length (ft).
- Minimum AWG is sized for load ÷ 0.8 (continuous), then the smallest size with drop ≤ 3% — e.g. 15 A → #12.
- If even 4/0 cannot stay under 3%, length and drop % show Exceeds safety (strike-through) until you enter a valid run.
Disclaimer: Field-reference only. Final wire sizing by a licensed electrician or professional engineer. These tools do not apply full CEC requirements and must not be used to work outside your licence. Terms §3.1.