G107A - Cable Selection (CCC)

The AS 3008 Table used to determine the current carrying capacity for cables that are buried direct underground is:

• Table 3 (1)

• Table 3 (2)

• Table 3 (3)

• Table 3 (4)

Answer explanation

AS 3008 Table 3 (3) Cables Buried Direct in the Ground

Which one of the following is not a factor to influence the selection of a cable to satisfy the circuit requirements?

• short circuit temperature limit

• voltage drop

• wholesale cost of the cable

• current carrying capacity

Answer explanation

The price of the cable does not factor into which cable must be used when calculating

The minimum current carrying capacity of a final sub circuit supplying a 18 kW, 400 V three phase industrial heater protected by a CB would be:

(Answer to the nearest WHOLE nuber)

What vertical spacing is required to avoid derating cables when clipped to a wall?

• 2 x Diameter

• 4 x Diameter

• 6 x Diameter

• 1 x Diameter

Answer explanation

AS 3008 Figure 1 b)

Minimum cable spacings to avoid derating

What is the maximum circuit length of 1.5 mm² TPS twin and earth cable supplying a spotlight and protected by a 10 A Type C circuit breaker so as not to exceed the maximum earth fault loop impedance for a 230 V installation?

Answer explanation

AS 3000 Table B1

Max route length for different size conductors

What is the maximum circuit length of 2.5 mm² TPS twin and earth cable supplying a motor and protected by a 20A Type D circuit breaker so as not to exceed the maximum earth fault loop impedance for a 230 V installation?

Answer explanation

AS 3000 Table B1

Max route length for different size conductors

What is the maximum value of Earth Fault Loop Impedance Z_S @ 230 V, for a single phase circuit wired in 6 mm² TPS cable when supplying a stationary cooking appliance in a domestic installation and protected by a 40 A Type C circuit breaker?

What value of voltage drop is permitted for a single phase 230V installation?

Answer explanation

230 x 5% = 11.5 V

5% is the maximum allowable percentage voltage drop for any electrical installation

What value of voltage drop is permitted for a single phase 400 V installation?

Answer explanation

400 x 5% = 20 V

5% is the maximum allowable percentage voltage drop for any electrical installation

Calculate the voltage drop on a 6mm² V90 3 phase multicore copper cable, if protected by a 32 A CB with a length of 30m

(Enter the entire number as the answer)