EZ Formula Guide



    Your easy-to-use guide on the go! Scroll through commonly used tables below.

Power Wheel

Place thumb over the unknown, select formula in that section.

Power Factor = Ratio of True to Apparent Power = W ÷ VA
Power Factor Percent = (kW ÷ kVA) × 100

Electrical Formulas for Calculating Amperes, Horsepower, Kilowatts and kVA


Table 250.66  Grounding Electrode Conductor for Alternating-Current Systems

 

Table 250.102(C)(1)

Grounded Conductor, Main Bonding Jumper, System Bonding Jumper, and Supply-Side Bonding Jumper for Alternating-Current Systems

Table 250.122  Minimum Size Equipment Grounding Conductors for Grounding Raceway & Equipment

 

310.15(B)(3)(a) Adjustment Factors

More than Three Current-Carrying Conductors in a Raceway or Cable.
Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are stacked or bundled longer than 24 in. (600 mm) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(3)(a).

CORRECTION FACTORS Table 310.15(B)(1)(1) (2023 NEC) based on 30˚C (86˚F)

 

Table 310.16. Ampacities of Insulated Conductors

Table 310.16 Ampacities of Insulated Conductors with Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried)



*See Section 240.4(D) for conductor overcurrent protection limitations.

Table 314.16(A) Metal Boxes

Table 314.16(B)(1)  Volume Allowance Required per Conductor

SINGLE-PHASE Transformers Voltage (Approx. Values) 


THREE-PHASE Transformers Voltage (Line-to-Line) (Approx. Values) 

Table 430.248   Full-Load Currents in Amperes, Single-Phase Alternating-Current Motors


The following values of full-load currents are for motors running at usual speeds and motors with normal torque characteristics. 

The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110 to 120 and 220 to 240 volts.

Table 430.250   Full-Load Current, Three-Phase Alternating-Current Motors

The following values of full-load currents are typical for motors running at speeds usual for belted motors and motors with normal torque characteristics. The voltages listed are rated motor voltages. The currents listed shall be permitted for system voltage ranges of 110-120, 220-240, 440-480, and 550-600 V.