Chauvin Arnoux F 62 Notice De Fonctionnement page 21

English
MEASUREMENT CATEGORY IV
MEASUREMENT CATEGORY IV is applicable to test
and measuring circuits connected at the source of the
building's low-voltage MAINS installation. This part of the
installation could have no over-current protective devices
between the transformer and connecting points of the
measuring circuit.
Example: measurements on devices installed before the
main fuse or circuit breaker in the building installation.
For your safety, use only cords complying with the IEC
61010 standard. Before each use, check that they are in
perfect working condition.
21 F 62 – F 65