Motors & Loads calculator
Motor Control Panel Load Calculator
This page is an MCC feeder-ampacity screen. For a 480 V lineup with one 65 A largest motor, 96.6 A of remaining motors, and 3 kVA of continuous non-motor load, the required feeder ampacity screens at 182.36 A before spare capacity and 227.95 A with a 25% planning adder.
Updated July 10, 2026
A 480V MCC with one 65A largest motor, 96.6A of remaining motor FLC, and 3 kVA of continuous non-motor load screens at about 182.4A of required feeder ampacity before any planning spare capacity is added.
Feeder ampacity = 1.25 x largest motor FLC + remaining motor FLC + 1.25 x continuous non-motor current + non-continuous non-motor current.
Enter the largest motor FLC, combined remaining motor FLC, and non-motor kVA below to screen MCC feeder ampacity and a planning spare-capacity view.
Example Calculations
How to Use
What this motor control panel load calculator does
This page is for one specific question: what feeder ampacity should you screen when a motor control panel or motor control center serves multiple motors plus optional line-side non-motor load? It is not a full MCC design package, breaker selector, conductor selector, or SCCR review tool.
Feeder-load basis
The screen follows the familiar multiple-motor feeder logic used in U.S. practice: one largest motor is counted at 125%, the remaining motors are counted at 100%, continuous non-motor load is counted at 125%, and non-continuous non-motor load is counted at 100%.
Required feeder ampacity = 1.25 x largest motor FLC + remaining motor FLC + 1.25 x continuous non-motor current + non-continuous non-motor current
Inputs that matter
- Largest motor full-load current: use one motor only, even if several motors tie for largest FLC
- Combined remaining motor FLC: add every other motor on the same feeder at 100%
- Continuous non-motor load: convert the stated kVA to current at the selected panel voltage, then apply 125%
- Non-continuous non-motor load: convert the stated kVA to current at the selected panel voltage and count it at 100%
Worked screening example
Suppose a 480 V MCC serves one 65 A largest motor, 96.6 A of remaining motors, and 3 kVA of continuous non-motor load.
- Largest motor contribution: 65 A x 1.25 = 81.25 A
- Remaining motors contribution: 96.6 A
- Continuous non-motor contribution: 3 kVA x 1000 / (sqrt3 x 480) x 1.25 = 4.51 A
- Required feeder ampacity: 81.25 + 96.6 + 4.51 = 182.36 A
If you add a 25% planning spare-capacity allowance, the planning screen rises to about 227.95 A. That planning result is useful for budgeting or bucket-space discussions, but it is not a substitute for the actual design basis and final equipment schedule.
Scope limits
- This page assumes you already know the motor full-load current values you want to use.
- This page does not derive motor FLC from horsepower or nameplate efficiency assumptions.
- This page does not size breakers, conductors, overloads, branch-circuit protection, or SCCR.
- This page does not prove that multiple motors will or will not run together. If diversity is part of the design basis, document it outside this screen.
Use the Motor Current Calculator when you still need a preliminary current basis. Use the Motor Cable Size Calculator when the next question is branch-circuit conductor screening. Use the Short Circuit Calculator when the real concern is fault current and downstream duty instead of feeder ampacity.
Common Applications
More applications. Open to review 2 additional use cases.
Frequently Asked Questions
Should I enter horsepower or actual motor full-load current on this page?
Enter the full-load current values you intend to use for the feeder basis. This page is not a horsepower-to-current engine. If you still need a current basis, establish that first and then return here.
What if two or more motors tie for the largest full-load current?
Treat one motor as the 125% motor and include the other equal motors in the remaining-motors total. The 125% adder is applied once to one largest motor contribution.
Can I use this page to pick the MCC main breaker or feeder conductor?
No. This page screens feeder ampacity only. Final breaker selection, conductor selection, temperature limits, short-circuit duty, SCCR, and project documentation remain separate tasks.
Why does the page ask for non-motor load in kVA?
Because mixed line-side non-motor load is commonly carried into the feeder basis as three-phase apparent power at the selected panel voltage. The page converts that kVA to current before applying the continuous or non-continuous multiplier.
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