Chauvin Arnoux C.A 6681 Notice De Fonctionnement page 41

English
Connecting the transmitter to an installation at the mains voltage
may cause a current of the order of the milliampere to flow in the circuit. Normally,
the transmitter must in this case be connected only between phase and neutral.
If the transmitter is accidentally connected between the phase and the protection
conductor, and there is a fault in the installation, all parts connected to the earth
may then be live.
This is why, when the device is used on a live installation, it must first be checked
that the installation tested complies with standards (NF-C-15-100, VDE-100, etc.,
depending on the country), in particular as regards the earth resistance and the
connection of the protection conductor (PE) to the earth.
C.A 6681 Cable locater 41