EAL unit 4 revision 4

Which device is this about: Its I rating must be equal to or above the normal operating current for the circuit.

• the cable

• the fuse

• the accessory

• the distribution board

Which device is this about: Its I rating must be equal to or higher than normal current carrying capacity of the protective device?

• the cable

• the fuse

• the accessory

• the distribution board

Calculate the total demand current for a lighting circuit it it contains 20 x 100W GLS lamp units and the diversity factor is 66%

• 7.8A

• 8.69

• 6A

• 5.7A

When cabling is routed through insulation, its rated current carrying capacity will be:

• decreased

• increased

• stay the same

• be doubled be meter embed

if the voltage drop in a final circuit is found to be excessive, the corrective action is to:

• limit the time under load

• boost the voltage through a transformer

• increase the CSA of the supply cable

• decrease the CSA of the supply cable

when overload and over current protection is necessary, which of the following is correct?

• Ib>In>It

• Ib<In>It

• Ib<In<It

• Ib>In>Iz

Which of the following is correct regarding earth fault loop impedance?

• Zs can be obtained by enquiry

• Ze can be obtained by enquiry

• Zs can be obtained by calculation

• Zs can be obtained by measurement

One disadvantage of using the tabulated values of Ze in the OSG is:

• they are hard to read

• they can be too high

• they are unreliable

• they can be too low

when checking earth fault loop impedance, which of the following can be used without correction?

• BS 7671

• GN3

• On Site Guide

• GS38

The usual correction factors used to calculate the derating factor of a cable are:

• thermal insulation, grouping, ambient temp and rewireable fuses

• external insulation, grouping, ambient temp and rewireable fuses

• cable type, grouping, rewireable fuses and ambient temp

• thermal insulation, cable type, ambient temp and grouping