303 #4 - Protective Conductors & Earthing Quiz

What does CPC stand for in electrical installations?

• Circuit Protective Conduit

• Central Power Control

• Circuit Protective Conductor

• Consumer Protective Contact

What is the purpose of a main protective bonding conductor?

• To operate switches

• To maintain voltage stability

• To equalise potential between metal parts

• To reduce energy use

Supplementary bonding is typically required in:

• Bedrooms

• Bathrooms

• Offices

• Roof spaces

What does Zs represent?

• Source voltage

• System resistance

• Earth fault loop impedance

• Safety zone

What units is Zs measured in?

• Volts

• Ohms

• Amps

• Watts

What is the maximum disconnection time for a 230V TN system on a final circuit ≤32A?

• 5 seconds

• 1 second

• 2 seconds

• 0.4 seconds

Which regulation chapter of BS7671 deals with disconnection times?

• Chapter 42

• Chapter 41

• Chapter 52

• Appendix 2

Ze refers to:

• Total circuit impedance

• Resistance of the live conductor

• External earth loop impedance

• Protective bonding value

If R1 + R2 = 0.67Ω and Ze = 0.35Ω, what is Zs?

• 1.12Ω

• 0.32Ω

• 0.67Ω

• 0.35Ω

Which conductor colour is used for main protective bonding?

• Red

• Blue

• Green/yellow

• Black