Earth fault loop impedance

What is the maximum Ze reading for a TN-C-S earthing arrangement?

• 0.25 Ohms

• 0.35 Ohms

• 0.8 Ohms

• 200 Ohms

The R1 is the...

• Line conductor

• CPC

• Neutral conductor

• Line 1 conductor

What earthing arrangement is shown?

• TT

• TN-C

• TN-C-S

• TN-S

Which of the following is correct?

• Ze=Zs + (R1+R2)

• R1+R2=Ze + Zs

• Zs=Ze + (R1+R2)

• Zs=Ze + (R1 + Rn)

The electrical system in which the connection to earth is by an earth electrode is:

• TT

• TN-C-S

• TN-S

• TN-C

Which one of the following is the correct name of the component which links the main earthing terminal of an installation to the means of earthing?

• Main protective bonding conductor

• Supplementary equipotential bond

• Earthing conductor

• Functional earth

What is represented by Z_s in the following formula:

Z_s=Z_e+(R₁+R₂)?

• Total earth fault loop impedance

• External earth fault loop impedance

• Final circuit earth fault loop impedance

• Combined resistance of the earth path

Why are TT earthing arrangements required to have an RCD for fault protection:

• It‟s the law

• The Earth return path could have a very low impedance

• The Earth return path could have a high impedance

• The ESQCR states that it must

The maximum earth fault loop impedance, permitted by BS 7671, on a TN system for a ring final circuit protected by a 30 A BS 1361 fuse and a protective conductor size of 1.5mm is:

• 1.14 Ohms

• 0.86 Ohms

• 1.92 Ohms

• 1.09 Ohms

The type of fault which occurs when a phase conductor comes in contact with a neutral conductor is called:

• An earth fault loop path

• A short-circuit fault

• A catastrophic fault

• An overload fault