Electrical Fault Finding B

The accessory pictured is often used in testing when conducting test using what particular method?

• Test method 2

• Test method 1

• Continuity of ring final conductors

• Test method 3

The Ze is to be measured as part of the initial verification process, what instrument should be used for this task?

• An earth fault loop impedance tester

• An insulation resistance tester

• An RCD tester

• A low resistance ohmmeter

The maximum value of earth electrode resistance for a TT installation protected by a 500mA RCD is given by BS7671 as

• 1660Ω

• 500Ω

• 160Ω

• 100 Ω

A 100mA RCD protecting a TT installation tested at 1/2 I should

• Operate within 300ms

• Operate within 200ms

• Not operate

• Operate within 40ms

The following readings were taken on a test performed on a ring final circuit, Line to Line 0.8 Ω Neutral to Neutral 0.8 Ω cpc to cpc 0.8 Ω . What would be the expected reading between line and cpc at each socket outlet?

• 1.6 Ω

• 0.4 Ω

• 0.8 Ω

• 0.2 Ω

What is the importance of verifying readings obtained with those listed within BS7671 and associated documents?

• The circuit is safe and within design parameters

• The circuit protection does not operate accidentally without warning

• The instrument is functioning correctly and within stated tolerances

• The instrument conforms to BS EN 61010

If two bonding conductors or equal length were connected in parallel the resistance would

• Increase

• Double

• Not change

• Halve

During a continuity of Ring final conductors test, 10 Sockets give a R1+R2 reading of 0.68 Ω, but one socket gives a reading of 0.92 Ω. What might that indicate?

• A spur on the circuit

• A trapped cpc in the back of the box

• A short circuit

• A high resistance fault

A polarity test is conducted to verify that

• There is no breakdown of the insulation of the conductor

• The resistance is sufficiently low to operate the protective device within the specified time

• The circuit protection will operate within a pre-determined time

• Every protective and single pole device is connected in the line conductor only

If 3 conductors equal in length and with a resistance of 1.5 Ω are connected in parallel, what is the total resistance?

• 4.5 Ω

• 0.5 Ω

• 2 Ω

• 15 Ω