Electric Motor Fuse Sizing Chart

Tection for motor branch circuits 430 52 but typically are not the maximum allowed.

Electric motor fuse sizing chart.

Amperes enter the maximum current in amps that will flow through the circuit. Read horizontally to the right until the distance is as great or greater than your installation. The largest size fuse shown in the chart is the 5ag or midget a name adopted from its use by the electrical industry and the national electrical code range which normally recognizes fuses of 9 16 x 2 as the smallest standard fuse in use. 8 branch circuit fuse size individual motor load with fuse overload protection no starter overload relays.

A motors with 1 15 service factor or temperature rise not over 40 degrees c size fuses at not more than 125 of the motor nameplate current rating. If motor running protection will be provided by the fuses select fuse ratings for correct type of motor from motor protection table columns headed without overload relays. Circuit breaker size and amps charts. B best protection is obtained by measuring motor running.

430 250 covering standard speed ac motors with normal torque characteristics. Select motor size from horsepower column making certain you are in the correct voltage. Motors are usually protected by both fuses or circuit breakers and by heater coils in a magnetic starter. Yet for many cases this fuse amp rating selection is smaller than the maximums allowed per columns 5 or 6 430 52.

Select fuse or breaker size from column 3 or 4. The maximum safe current limit is 80 of the rated size of breaker except some motors. In some cases this smaller amp rating. Fuse ratings for motors with special characteristics may need to vary from given values.

This fuse sizing is normally large enough to allow the. This fuse sizing is normally large enough to allow the overload protective device to operate on overloads without opening the fuse. Motor full load amps are taken from motors currently used by champion. For motors it is recommended to multiply the nameplate fla by 1 25 for wire sizing.

Single phase voltages are usually 115v or 120v while three phase voltages are typically 208v 230v or 480v. The following table gives wire breaker and fuse sizes based on horsepower voltage and phase. Keep in mind that the breaker size should not increase the max amperage rating of cable and wire. Below is the given chart showing the of max current rating of breaker size for different types of load currents.

Chart to determine fuse breaker and wire sizes for electric motors for single phase a c. Voltage enter the voltage at the source of the circuit. Fuses open the circuit quickly in case of a massive overload or short circuit.