Table $5\mathrm{.}1$ Typical values of resistivity for different soils.

Table $5\mathrm{.}2.$ Earthing resistance and the soil resistivity

Self$-$Evaluation Questions:

$1.$ Using the earthing electrode formula calculate resistivity of the soil tested and fill in Table $5\mathrm{.}1.$

$2.$ Does the test electrode used in the present experiment provide sufficient protection for lighting protective conductor?

$3.$ What is the standard rod electrode dimensions and burial length of a protective earth electrode?

$4.$ If an earth electrode cannot be driven through a sufficient depth into the ground, then electrode systems typified in the text cannot be used. Which electrode configuration can you suggest?

$5.$ Regulation requires that lighting protective conductor and $\backslash ($ t $\backslash )$ main installation earthing terminal should be connected together. What is the reason for this?

$6.$ Define resistance areas of an earthing electrode. How the separation between electrodes T and T$1,$ and T and T$2$ affect resistance reading of the meter?

$7.$ How the soil resistivity does change with humidity and temperature? Draw expected variations of humidity and temperature on the same graph against resistivity?

$8.$ What type of voltage should be applied across potential electrode T$1$ and T$2?$ Explain the reason.

$9.$ Is it safe to use the earth electrode tested in part $8$ of the procedure in TTsupply system? Explain the reason.