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パネル負荷計算機

分電盤の総需要負荷とアンペア数を推定します（簡易NEC 220.42方式）。

はじめに

Panel Load Calculator — Estimate total electrical panel demand load and amperage (simplified NEC 220.42 method). Enter General lighting load (VA), Appliance loads (VA), System voltage (V) to get an instant, accurate result.

計算式

A simplified, illustrative demand calculation: general lighting load is counted at 100% for the first 10,000 VA and 40% for the remainder, appliance load is added at 100%, and the total VA is converted to amps via I = VA / V. This is NOT the literal NEC Table 220.42 dwelling-unit demand schedule (which uses 3,000 VA at 100%, 35% from 3,001–120,000 VA, and 25% above that) — real panel/service load calculations must follow NEC Article 220 in full, including the correct occupancy-specific demand factors and all required loads.

ステップごとの説明

  1. Enter the General lighting load (VA).
  2. Enter the Appliance loads (VA).
  3. Enter the System voltage (V).
  4. Click Calculate to see your result instantly.

実例

Example: With General lighting load (VA) = 12000, Appliance loads (VA) = 5000, System voltage (V) = 240, the Panel Load Calculator gives Total Demand Va: 15800, Demand Amps: 65.8333, Basis: Simplified NEC 220.42-style demand calc.

よくある質問

Is this a substitute for a real NEC load calculation?
No. This tool gives a rough estimate using simplified demand percentages for educational purposes only. An actual electrical service or panel load calculation must follow the specific procedure in NEC Article 220 (and any local amendments) and should be performed or verified by a licensed electrician.
Why does demand factoring reduce the load at all?
Demand factors exist because not every circuit in a building draws its full rated load simultaneously; NEC Article 220 permits calculating a lower "demand" load for the service/feeder based on statistical diversity, rather than summing every connected load at 100%.
What inputs does the Panel Load Calculator need?
You'll need to provide: General lighting load (VA), Appliance loads (VA), System voltage (V). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Panel Load Calculator?
The Panel Load Calculator applies the formula exactly as calculated — A simplified, illustrative demand calculation: general lighting load is counted at 100% for the first 10,000 VA and 40% for the remainder, appliance load is added at 100%, and the total VA is converted to amps via I = VA / V. This is NOT the literal NEC Table 220.42 dwelling-unit demand schedule (which uses 3,000 VA at 100%, 35% from 3,001–120,000 VA, and 25% above that) — real panel/service load calculations must follow NEC Article 220 in full, including the correct occupancy-specific demand factors and all required loads. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Panel Load Calculator free to use?
Yes, the Panel Load Calculator is completely free, requires no signup, and runs instantly in your browser.

パネル負荷計算機について

The Panel Load Calculator uses a real, verifiable formula — A simplified, illustrative demand calculation: general lighting load is counted at 100% for the first 10,000 VA and 40% for the remainder, appliance load is added at 100%, and the total VA is converted to amps via I = VA / V. This is NOT the literal NEC Table 220.42 dwelling-unit demand schedule (which uses 3,000 VA at 100%, 35% from 3,001–120,000 VA, and 25% above that) — real panel/service load calculations must follow NEC Article 220 in full, including the correct occupancy-specific demand factors and all required loads. — so results are accurate every time, not an approximation.