The C.A 6474 is designed for use with the C.A 6472 earth tester to measure pylon earths
When used with the C.A 6472, the C.A 6474 allows the following types of measurements:
Global earth of pylons
Earth resistance of each of the pylon's footings
Quality of the overhead protective earth cable connection
Active measurement (injection by the C.A 6472)
Passive measurement (use of stray currents)