Utilization categories

In electrical engineering utilization categories are defined by IEC standards and indicate the type of electrical load and duty cycle of the loads to ease selection of contactors and relays.

Utilization Category	Typical Application	Applicable IEC norm
AC-1	Non-inductive or slightly inductive loads, example: resistive furnaces, heaters	60947-4-1
AC-2	Slip-ring motors: switching off	60947-4-1
AC-3	Squirrel-cage motors: starting, switches off motors during running time	60947-4-1
AC-4	Squirrel-cage motors: starting, plugging, inching	60947-4-1
AC-5a	Switching of discharge lamps	60947-4-1
AC-5b	Switching of incandescent lamps	60947-4-1
AC-6a	Switching of transformers	60947-4-1
AC-6b	Switching of capacitor banks	60947-4-1
AC-7a	Slightly inductive loads in household appliances: examples: mixers, blenders	60947-4-1 61095
AC-7b	Motor-loads for household appliances: examples: fans, central vacuum	60947-4-1 61095
AC-8a	Hermetic refrigerant compressor motor control with manual resetting overloads	60947-4-1
AC-8b	Hermetic refrigerant compressor motor control with automatic resetting overloads	60947-4-1
AC-12	Control of resistive loads and solid state loads with opto-coupler isolation	60947-5-2
AC-13	Control of solid state loads with transformer isolation	60947-5-1
AC-14	Control of small electromagnetic loads	60947-5-1
AC-15	Control of A.C. electromagnetic loads	60947-5-1
AC-20	Connecting and disconnecting under no-load conditions	60947-3
AC-21	Switching of resistive loads, including moderate overloads	60947-3
AC-22	Switching of mixed resistive and inductive loads, including moderate overloads	60947-3
AC-23	Switching of motor loads or other highly inductive loads	60947-3
A	Protection of circuits, with no rated short-time withstand current	60947-3
B	Protection of circuits, with a rated short-time withstand current	60947-3
DC-1	Non Inductive or slightly inductive loads, resistance furnaces, heaters	60947-4-1
DC-3	Shunt-motors, starting, plugging(1), inching(2), dynamic braking of motors	60947-4-1
DC-5	Series-motors, starting, plugging(1), inching(2), dynamic braking of motors	60947-4-1
DC-6	Switching of incandescent lamps	60947-4-1
DC-12	Control of resistive loads and solid state loads with opto-coupler isolation	60947-5-1 60947-5-2
DC-13	Control of D.C. electromagnetics	60947-5-1 60947-5-2
DC-14	Control of D.C. electromagnetic loads having economy resistors in the circuit	60947-5-1
DC-20	Connecting and disconnecting under no-load conditions	60947-5-1
DC-21	Switching of resistive loads, including moderate overloads	60947-5-1
DC-22	Switching of mixed resistive and inductive loads, including moderate overloads (i.e. shunt motors)	60947-5-1
DC-23	Switching of highly inductive loads (i.e. series motors)	60947-5-1

See also

NEMA contact ratings