The 2012 Edition of NFPA 70E references the ANSI IEC 61010-1 standard that defines test tool category ratings. The following partial list describes the IEC category ratings:
- CAT I — Protected electronic equipment.
- CAT II — Single-phase receptacle-connected loads such as appliances and portable tools.
- CAT III — 3-phase distribution including single-phase commercial lighting and equipment in fixed locations such as switchgear and polyphase motors.
- CAT IV — 3-phase at the utility connection, outdoor conductors, electricity meters, and service entrances.
It's important to note that CAT ratings as marked on test and measurement equipment have no relation to the PPE Hazard Risk Categories listed in NFPA 70E