NEMA contact ratings are how much current at a rated voltage a relay or other pilot device can switch. The current rating of smaller NEMA contactors or their auxiliaries are defined by NEMA ICS 5: Industrial Control and Systems, Control Circuit and Pilot Devices standard. The nomenclature is a letter followed by a three-digit number, the letter designates the current rating of the contacts and the current type (i.e., AC or DC) and the number designates the maximum voltage design values.
AC Contact Ratings Contact Rating Designation Thermal Current Voltage A150 10 150 A300 10 300 A600 10 600 B150 5 150 B300 5 300 B600 5 600 C150 2.5 150 C300 2.5 300 C600 2.5 600 D150 1 150 D300 1 300 E150 0.5 150
DC Contact Ratings Contact Rating Designation Thermal Current Voltage Voltamperes N150 10 150 275 N300 10 300 275 N600 10 600 275 P150 5 150 138 P300 5 300 138 P600 5 600 138 Q150 2.5 150 Q300 2.5 300 Q600 2.5 600 R150 1 150 R300 1 300
See also Utilization categories
References