Q$3.(10$ marks$)$ A cable feeds a $230$V$,$ single$-$phase electric pump and lighting point in an external building of a factory, the total length of the twin with earth $4$mm$2/2\mathrm{.}5$mm$2$ pvc$-$insulated copper cable is $30$m$,$ protection is by a BS EN$60898,$ type B$,32$A MCB in a distribution board at the suppliers$$ intake position. The tested value of Ze at the intake position is $0\mathrm{.}35.$ This is a fixed$-$equipment circuit but is in adverse conditions, thus this circuit must disconnect within $0\mathrm{.}4$s$.($a$)$ Estimate the value of the earth fault loop impedance, Zs$.(4$ marks$)($b$)$ What is the maximum permissible value of Zs according to the BS $7671$ requirements. Does the estimated value in compliance with the BS$7671$ requirements? $(2$ marks$)($c$)$ Calculate the fault current and the MCB disconnection time. $(1\mathrm{.}5$ marks$)($d$)$ Evaluate the suitability of the cpc conductor size from the thermal constraint. $(1\mathrm{.}5$mark$)($e$)$ According to Bahrain regulation, what is the recommended size of the earth lead conductor if the size of the main cable of a building is $50$ mm$2?($