총 부하 감사
필요한 총 용량을 결정하기 위해 여러 장치와 기계를 통합합니다. 패널 사이징 및 인프라 계획에 필수적입니다.
네트워크 장치 추가
패널 부하 레지스트리
활성 회로 레지스트리
*권장 차단기에는 125% 연속 부하 안전 계수가 포함됩니다.
부하 계산 공식
총 부하는 소모되는 전류, 필요한 차단기, 그리고 회로가 안전하게 크기가 조정되었는지를 결정합니다.
총 회로 전류
I = ΣWatts ÷ Voltage 회로의 모든 부하를 와트 단위로 합산한 다음 공급 전압으로 나누어 총 전류 수요를 구합니다.
차단기 크기 (NEC 규칙)
Breaker ≥ Total Amps × 1.25 NEC는 연속 부하(3시간 이상 작동)가 차단기 용량의 80%를 초과하지 않도록 요구합니다 — 이는 부하의 125%로 차단기 크기를 조정하는 것과 같습니다.
How to Calculate Electrical Load
A load calculation determines how much current a circuit, panel, or service must supply to all connected devices. Accurate load calculations prevent overloaded circuits, nuisance breaker trips, overheated wiring, and fire hazards. They are also required by electrical codes before adding circuits or service upgrades.
The 80% Rule for Continuous Loads
Any load that operates continuously for 3 hours or more is a "continuous load" under the NEC. Continuous loads must not exceed 80% of the circuit breaker's rating. A 20A breaker can sustain no more than 16A of continuous current. This prevents breakers from operating near their thermal limit indefinitely, which reduces reliability and lifespan.
Types of Electrical Loads
- Resistive Loads: Electric heaters, incandescent bulbs, toasters. PF = 1.0. Current and voltage are in phase — easiest to calculate.
- Inductive Loads: Motors, fans, compressors, transformers. PF typically 0.7–0.9. Draw additional reactive current beyond what wattage suggests.
- Capacitive Loads: Certain electronic power supplies and long cable runs. PF leading. Less common in typical building loads.
- Non-Linear Loads: Variable speed drives, computers, LED drivers. Introduce harmonic currents that can cause overheating in neutral conductors and transformers.
Step-by-Step Load Calculation
- List All Loads: Include every device connected to the circuit or panel — lights, outlets, fixed appliances, HVAC, etc.
- Note Each Wattage: Use nameplate ratings. For receptacle circuits, NEC allows 180VA per outlet as a standard assumption.
- Classify Continuous vs. Non-Continuous: Apply the 80% rule only to loads running 3+ hours continuously.
- Sum the Total Amps: Divide total watts by supply voltage to get current. Add motor startup surge separately if needed.
- Select Breaker and Wire: Choose a breaker rated above your calculated load (with the 125% rule for continuous loads), and size wire to match using NEC ampacity tables.