Общая Нагрузка Аудит
Объедините несколько устройств и машин, чтобы определить необходимую общую мощность. Необходимо для подбора щита и планирования инфраструктуры.
Добавить устройство сети
Реестр нагрузки щита
Реестр активной цепи
*Рекомендуемый автомат включает коэффициент безопасности 125% для длительной нагрузки.
Формулы расчёта нагрузки
Общая нагрузка определяет потребляемый ток, необходимый автомат и безопасность размера вашей цепи.
Общий ток цепи
I = ΣWatts ÷ Voltage Сложите все нагрузки в цепи в ваттах, затем разделите на напряжение питания, чтобы получить общую потребность в токе.
Номинал автомата (Правило NEC)
Breaker ≥ Total Amps × 1.25 NEC требует, чтобы длительные нагрузки (работающие 3+ часа) не превышали 80% номинала автомата — что эквивалентно подбору автомата на 125% от нагрузки.
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.