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Circuit Breaker Size Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.

公式

Breaker Size = Load Watts / Voltage × 1.25 (125% NEC rule)

ステップバイステップガイド

  1. 1Calculate total load in watts, divide by voltage, multiply by 1.25
  2. 2Apply the formula using your project measurements
  3. 3Add required safety factors or waste allowances per code

解いた例

入力
2400W load, 120V circuit
結果
Breaker = 2400/120 × 1.25 = 25A → use 30A breaker

避けるべきよくある間違い

  • Not applying code-required safety factors or derating
  • Forgetting to account for waste and cut losses in material estimates

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