Electric Wiring, 3rd Edition

176 Inspection and testing

To check that the resistance measured is

a

true value, two further readings

should be taken with the second auxiliary electrode T

2

moved 6 m nearer to

and then 6 m farther from T. If the three results are substantially constant,

then

the

mean

of

the

three readings

can be

taken

as

the resistance of

the

earth

electrode T. If the results are not constant then the test should be repeated

with

T

and

Tj

farther apart.

Operation of residual current operated devices

These tests must be carried out after installation and connection, indepen-

dently of the test facility included in the device.

In the recommended test for a residual-current-operate ...