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Commercial and Industrial Wiring and Raceway Calculator
Formulas
- Conversion Formulas
- Electrical Formulas Based on 60 Hz
- Parallel Circuits
- Series Circuits
- Transformer Amperes
- Voltage Drop
- Code Rules
Conversion Formulas
- Area of Circle = πr2
- Break-even Dollars = Overhead Cost $/Gross Profit %
- Busbar Ampacity AL = 700A sq. in. and CU = 1,000A sq. in.
- Centimeteres = Inches/2.54
- Inch = 0.0254 Meters
- Inch = 25.40 Milimeters
- Kilometer = 0.6213 Miles
- Length of Coiled Wire = Diameter of Coil (average) × Number of Coils × π
- Lightning Distance in Miles = Seconds between flash and thunder/4.68
- Meter = 39.37 Inches
- Mile = 5,280 ft, 1,760 yards, 1,609 meters, 1.609 km
- Millimeter = 0.03937 Inch
- Selling Price = Estimated Cost $/(1 - Gross Prom%)
- Speed of Sound (Sea Level) = 1,128 fps or 769 mph
- Temp C = (Temp F - 32)/1 .80
- Temp F = (Temp C × 1.80) + 32
- Yard = 0.9144 Meters
Electrlcal Formulas Based on 60 Hz
- Capacitive Reactance (XC) in Ohms= 1/(2πfC)
- Effective (RMS) ac Amperes = Peak Amperes × 0.707
- Effective (RMS) ac Volts = Peak Volts × 0.707
- Efficiency (percent) = Output/Input × 100
- Efficiency = Output/Input
- Horsepower = Output Watts/746
- Inductive Reactance (XL) in Ohms = 2πfL
- Input = Output/Efficiency
- Neutral Current (Wye) = √(L12 +L22 +L32 )-[(L1 × L2)+(L2 × L3)+(L1 × L3)]
- Output = Input × Efficiency
- Peak ac Volts = Effective (RMS) ac Volts × √2
- PeakAmperes = Effective (RMS) Amperes × √2
- Power Factor (PF) = Watts/VA
- VA (apparent power) = Volts × Ampere or Watts/Power Factor
- VA Single-Phase = Volts × Amperes
- VA Three-Phase = Volts × Amperes × √3
- Watts (real power) Single-Phase = Volts × Amperes × Power Factor
- Watts (real power) Three-Phase = Volts × Amperes × Power Factor × √3
Parallel Circuits
- Note 1: Total resistance is always less than the smallest resistor
RT = 1/[(1/R1) + (1/R2) + (1/R3) .. ] - Note 2: Total current is equal to the sum of the currents of all parallel resistors
- Note 3: Total power is equal to the sum of power of all parallel resistors
- Note 4: Vollage is the same across each of the parallel resistors
Series Circuits
- Note 1 : Total resistance is equal to the sum of all the resistors
- Note 2: Current in the circuit remains the same through all the resistors
- Note 3: Vollage source is equal to the sum of vollage drops of all resistors
- Note 4: Power of the circun is equal to the sum of the power of all resistors
Transformer Amperes
- Secondary Amperes Single-Phase = VA/Volts
- Secondary Amperes Three-Phase = VA/(Volts × √3)
- Secondary Available Fault Single-Phase = VA/(Volts × % Impedance)
- Secondary Available Fault Three-Phase = VA/(Volts × √3 × % Impedance)
- Delta 4-Wire: Line Amperes = Phase (one winding) Amperes × √3
- Delta 4-Wire: Line Volts= Phase (one winding) Volts
- Delta 4-Wire: High-Leg Voltage (L-to-G) = Phase (one winding) Volts × 0.50 × √3
- Wye: Line Volts = Phase (one winding) Volts × √3
- Wye: Line Amperes = Phase (one winding) Amperes
Voltage Drop
- VD (Single-Phase) = 2KID/Cmils
- VD (Three-Phase) = √3 KID/Cmils
- Cmils (Single-Phase) = 2KID/VD
- Cmils (Three-Phase) = √3 KID/VD
Code Rules
- Breaker/Fuse Ratings - 240.6(A)
- Conductor Ampacity - 310.15 and Table 310.15(B)(16)
- Equipment Grounding Conductor - 250.122
- Grounding Electrode Conductor - 250.66
- Motor Conductor Size - 430.22 (Single) 430.24 (Multiple)
- Motor Short-Circuit Protection - 430.52
- Transformer Overcurrent Protection - 450.3
Legend
Find all values for the information listed under formulas here.
Legend
- π(Pi) = 3.142 (approximately)
- √2 = 1.414 (approximately)
- √3 = 1.732 (approximately)
- f = frequency
- r = radius
- d = diameter
- C = Capacitance (farads)
- L = Inductance (henrys)
- Cmils = Circular Mils
- VD = Volts Drop
- I = Amperes of load
- D = Distance one way
- K75°C = (12.90 ohms CU) (21.20 ohms AL)
