Overvoltage category (OVC - Overvoltage category) IEC 60947-1. Annex H

Standard IEC 60664-1 stipulates that it is up to the user to select a measurement device with a sufficient overvoltage category, depending on the network voltage and the transient overvoltages likely to occur.

Four overvoltage categories define the field of use for a device.

• Cat. I. Devices supplied by a SELV isolating transformer or a battery.

• Cat. II. Residential distribution, handheld or laboratory tools and devices connected to standardised 2P + earth electrical outlets (230 V).

• Cat. III. Industrial distribution, fixed distribution circuits in buildings (main low voltage switchboards, rising mains, elevators, etc.).

• Cat. IV. Utility substations, overhead lines, certain industrial equipment.