Electrical Load Calculator

Calculator

Load Types

Formulas

Wire Sizing

Safety

Select calculation type and enter known values to calculate electrical parameters using Ohm's Law and power formulas.

⚡

Power (P)

Calculate watts from volts & amperes

🔌

Current (I)

Calculate amperes from power & voltage

🔋

Voltage (V)

Calculate volts from power & current

🎯

Resistance (R)

Calculate ohms using Ohm's Law

🏠

Load Analysis

Circuit loading & wire sizing

Circuit Type

Power Factor

Safety Factor (%)

Circuit Diagram

LOAD

→ I

Basic electrical circuit with voltage source and load

Common Electrical Loads

Typical power consumption values for common electrical devices and appliances.

Residential Loads

💡

LED Light Bulb

5-15 W

Energy efficient lighting. Replace with actual wattage from bulb rating.

❄️

Refrigerator

150-800 W

Continuous load with compressor cycling. Average 400W for calculations.

📺

Microwave Oven

800-1500 W

High power intermittent load. Requires dedicated 20A circuit.

❄️

Air Conditioner

1000-5000 W

Major load with starting surge. Motor load with power factor considerations.

🚿

Electric Water Heater

3000-5500 W

High power resistive load. Typically 240V circuit required.

👕

Washing Machine

500-2000 W

Variable load with motor and heating elements. Power factor considerations.

Commercial & Industrial Loads

⚙️

1 HP Motor

746 W

Standard motor rating. Account for efficiency and power factor (0.8-0.9).

💻

Desktop Computer

300-800 W

Variable load depending on usage and components. UPS consideration needed.

🖥️

Server Rack

2000-8000 W

High density load with redundancy requirements. Cooling considerations.

🛗

Elevator Motor

10000-50000 W

Large motor load with regenerative capability. Variable frequency drive.

Electrical Formulas

Essential electrical formulas for power, current, voltage, and resistance calculations.

Ohm's Law & Power Formulas

⚡ Power Formulas

P = V × I

P = V² ÷ R

P = I² × R

Power (P) in watts can be calculated using voltage (V), current (I), or resistance (R).

🔌 Current Formulas

I = P ÷ V

I = V ÷ R

I = √(P ÷ R)

Current (I) in amperes. Essential for wire sizing and circuit protection.

🔋 Voltage Formulas

V = P ÷ I

V = I × R

V = √(P × R)

Voltage (V) in volts. Determines insulation requirements and safety considerations.

🎯 Resistance Formulas

R = V ÷ I

R = V² ÷ P

R = P ÷ I²

Resistance (R) in ohms. Important for load analysis and voltage drop calculations.

AC Power Calculations

🔄 Single Phase AC

P = V × I × PF

S = V × I

Q = V × I × sin(θ)

P = Real Power (W), S = Apparent Power (VA), Q = Reactive Power (VAR), PF = Power Factor

⚡ Three Phase AC

P = √3 × VL × IL × PF

P = 3 × VPH × IPH × PF

S = √3 × VL × IL

VL = Line Voltage, IL = Line Current, VPH = Phase Voltage, IPH = Phase Current

📐 Power Factor

PF = P ÷ S

PF = cos(θ)

θ = arccos(PF)

Power factor ranges from 0 to 1. Lower values indicate reactive loads requiring larger conductors.

📊 Electrical Efficiency

η = Pout ÷ Pin

Loss = Pin - Pout

%Loss = Loss ÷ Pin × 100

Efficiency (η) as decimal, power loss in watts, percentage loss for energy analysis.

Wire Sizing & Circuit Protection

Wire sizing tables and circuit protection requirements based on NEC standards.

Copper Wire Current Capacity (75°C)

Wire Size (AWG)	Current (A)	Voltage Drop (V/100ft @75°C)	Typical Applications
14 AWG	15A	0.25	Lighting circuits, small appliances
12 AWG	20A	0.16	General outlets, small motors
10 AWG	30A	0.10	Large appliances, AC units
8 AWG	40A	0.063	Electric ranges, large motors
6 AWG	55A	0.039	Sub-panels, large appliances
4 AWG	70A	0.025	Main feeders, large loads
2 AWG	95A	0.016	Service entrances, large panels
1/0 AWG	125A	0.010	Main service panels
2/0 AWG	145A	0.008	Large service entrances
4/0 AWG	195A	0.005	Commercial services

Circuit Protection Requirements

🔐 Breaker Sizing

Breaker ≤ Wire Rating

Motor Load = FLA × 1.25

Circuit breaker rating must not exceed wire ampacity. Motor loads require 125% sizing factor.

📏 Voltage Drop

VD = 2 × I × R × L

%VD = VD ÷ V × 100

Voltage drop should not exceed 3% for branch circuits, 5% total. Factor of 2 for single phase.

⚡ Load Calculations

Total Load = Sum of all loads

Demand Load = Total × DF

Apply demand factors (DF) for different load types. Not all loads operate simultaneously.

🔧 Conduit Fill

Fill % = Wire Area ÷ Conduit Area

Max Fill: 40% (3+ wires)

Conduit fill percentages: 53% (1 wire), 31% (2 wires), 40% (3+ wires) per NEC.

Electrical Safety

Critical safety information for electrical work and load calculations.

⚠️ Safety Warnings

🚫 Licensed Electrician Required

All electrical work must be performed by licensed electricians and inspected per local codes. These calculations are for estimation only.

⚡ High Voltage Danger

Electrical work involves risk of shock, electrocution, and fire. Turn off power at breaker and verify with tester before working.

🔥 Fire Prevention

Overloaded circuits cause fires. Never exceed wire ratings or bypass safety devices. Use proper GFCI and AFCI protection.

📋 Code Compliance

Follow local electrical codes (NEC in US). Obtain permits for electrical work. All installations must pass inspection.

🛡️ Protection Devices

🔌 GFCI Protection

Required in bathrooms, kitchens, garages, basements, and outdoor areas. Protects against ground faults (5mA trip).

🔥 AFCI Protection

Required in bedrooms and living areas. Detects arc faults that can cause fires. Advanced protection technology.

⚡ Surge Protection

Whole-house surge protectors protect against voltage spikes. Essential for sensitive electronic equipment.

🔐 Overcurrent Protection

Circuit breakers and fuses protect against overloads and short circuits. Proper sizing is critical for safety.

⚡ Electrical Load Calculator