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[1] 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.
| 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 |
| 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
References