FLA stands for Full Load Amps. It’s the amount of electrical current a motor draws when running at its rated horsepower and voltage under full load. You’ll find this number printed directly on the motor’s nameplate, and it’s the starting point for sizing the wiring, circuit breakers, and overload protection for that motor.
What FLA Tells You
Every motor nameplate lists a handful of key specs: horsepower, voltage, RPM, and FLA. The FLA number tells you how many amps the motor will pull from the circuit when it’s doing the maximum work it was designed to do. A 5-horsepower motor on a 230-volt circuit, for example, might have an FLA of around 15 amps. That’s the current it draws at full output under normal conditions.
Think of FLA as the motor’s “normal operating maximum.” If the motor is running a lighter load, it draws fewer amps. If it’s working at full capacity, it draws the FLA value. This number is specific to each motor because manufacturing tolerances, efficiency, and design vary from one unit to the next.
How FLA Is Used for Wiring and Protection
FLA directly affects how you set up the electrical circuit feeding the motor. There are two main areas where it matters: conductor sizing and overcurrent protection.
For wire sizing, the National Electrical Code requires conductors with an ampacity of at least 125% of the motor’s full load current. So if a motor draws 20 amps at full load, the wires feeding it need to safely carry at least 25 amps. This extra margin accounts for the heat that builds up during sustained operation.
For overload protection (the device that shuts the motor off if it overheats or gets mechanically stuck), the trip setting is typically capped at 115% of the nameplate FLA. This tight margin protects the motor from damage without tripping during normal use.
Circuit breaker sizing follows a slightly different path. The NEC actually directs electricians to use standardized full load current (FLC) values from reference tables rather than the nameplate FLA when calculating branch circuit protection. The distinction matters because breakers need to handle startup surges without nuisance tripping, and the NEC tables provide consistent baseline numbers. For an inverse time breaker, the starting point is 250% of the table FLC value.
FLA vs. LRA: Running Current vs. Startup Current
FLA only describes what the motor draws while it’s running at full speed under load. When a motor first starts up, it pulls far more current for a brief moment. This startup surge is called Locked Rotor Amps, or LRA, and it’s typically five to seven times the motor’s FLA. A motor with an FLA of 10 amps might draw 50 to 70 amps for a fraction of a second during startup.
LRA matters when choosing starters and circuit breakers. A breaker sized only for running amps would trip every time the motor kicked on. Different starter types reduce the inrush to varying degrees. A star-delta (wye-delta) starter cuts inrush to roughly 33% of the full LRA, while a solid-state starter brings it down to about 45% of LRA. Understanding both FLA and LRA ensures the motor can start reliably without tripping its protection devices.
FLA vs. Service Factor Amps
Some motors have a service factor rating on the nameplate, often 1.15 or 1.25. The service factor tells you how much the motor can be overloaded beyond its rated horsepower for short periods. A 1.15 service factor means the motor can handle 15% more output than its rated load temporarily.
When a motor operates at its service factor limit, it draws more current than the nameplate FLA. This higher current is sometimes called Service Factor Amps, or SFA. For a motor with an FLA of 20 amps and a service factor of 1.15, the SFA would be roughly 23 amps.
Running at service factor amps is meant for intermittent overloads, not continuous operation. Sustained use at that level generates extra heat, reduces efficiency, and shortens the motor’s lifespan. If you notice a motor consistently drawing current above its FLA, either the load is too heavy for that motor or something mechanical is causing excess drag.
Reading FLA on a Nameplate
On most motor nameplates, FLA appears alongside the voltage rating, and many motors list more than one pair. A dual-voltage motor might show “230V / 460V” with corresponding FLA values like “14.0 / 7.0.” The lower voltage always corresponds to the higher amperage because the motor needs more current to produce the same power at a lower voltage. Make sure you’re reading the FLA that matches the voltage your circuit actually supplies.
You may also see the abbreviation “FLC” (Full Load Current) used interchangeably with FLA in some contexts. In practice, FLA usually refers to the specific value stamped on a particular motor’s nameplate, while FLC refers to the standardized values listed in NEC reference tables for a given motor size and voltage. Both describe the same concept, but the NEC distinction between them affects how electricians calculate branch circuit protection.