Question 1

During an initial verification three conditions must be verified, one of these conditions as stated in BS7671 is:

Accepted Answer

One of the three conditions that must be verified during an initial verification is that all electrical equipment has been installed in compliance with section 511 of BS7671. Therefore, choice C is correct. The other options (A and D) are not specific enough to cover all the necessary requirements for an initial verification.

Question 2

A non statutory document which may be referred to during the inspection of an electrical installation is:

Accepted Answer

The On Site Guide is a non-statutory document produced by the Institution of Engineering and Technology (IET) which provides practical guidance for electricians installing and maintaining electrical systems. While not legally required to be followed, it is a widely recognized industry standard and may be referred to during inspections. ESQCR 2002, HASWA 1974, and EAWR 1989 are all statutory documents that set legal requirements and regulations for electrical installations and workplace health and safety.

Question 3

A statutory document which may be referred to during initial verification is

Accepted Answer

D

Question 4

The purpose of an initial verification as described in GN3 is

Accepted Answer

An initial verification is performed to confirm by inspection and test that the installation complies with the design and construction aspects of BS 7671. This ensures that the installation is safe and complies with the standards set out in GN3.

Question 5

A test value which may be obtained by the use of an RCD tester would be

Accepted Answer

The answer of A test value which may be obtained...

Question 6

In sequence the first three tests carried out on a ring circuit would be

Accepted Answer

The first three tests carried out on a ring circuit should be the ring final circuit test, insulation resistance test, and earth fault loop impedance. The ring final circuit test will confirm the correct connection of each conductor and that continuity exists around the ring. The insulation resistance test will identify any breaks or insulation defects in the cable. The earth fault loop impedance test will determine the effectiveness of the earthing system and identify any faults or malfunctions in the protective devices.

Question 7

An insulation resistance test carried out on five circuits of an electrical installation provided the following results, 50MO, 39MO, 56MO, 83MO and 26MO. Calculate the expected resistance if all of the circuits were to be measured together in parallel

Accepted Answer

When resistors are connected in parallel, the total resistance is calculated using the formula 1/Rtotal = 1/R1 + 1/R2 + ... + 1/Rn. Therefore, the expected resistance when all circuits are measured together in parallel is 1/((1/50)+(1/39)+(1/56)+(1/83)+(1/26)) = 8.77MΩ.

Question 8

A special location which may be connected to a TN-C-S system is

Accepted Answer

The answer of A special location which may be connected...

Question 9

The insulation resistance test voltage which may be applied to a circuit containing surge protection is

Accepted Answer

The insulation resistance test voltage for a circuit containing surge protection should not exceed 250v d.c. Exceeding this voltage could damage the surge protection components and lead to false readings. Therefore, option C is the best choice.

Question 10

The number of tests required when carrying out a resistance test on an earth electrode which is to be used with a generator is

Accepted Answer

Three tests are typically required to measure the resistance of an earth electrode: the fall-of-potential method, the dead earth method, and the clamp-on method.

Question 11

State one situation within a domestic installation which would require the installation of an RCD

Accepted Answer

An RCD is required for additional socket outlets in a bedroom to provide protection against electric shock, as per current electrical safety regulations.

Question 12

An earth electrode test is to be carried out using an earth electrode tester, if the electrode under test is to be inserted to a depth of 2.5m the minimum recommended distance for the test probe C2 is

Accepted Answer

The minimum recommended distance for the test probe C2 when conducting an earth electrode test is typically at least 10 times the depth of the electrode. Since the electrode is inserted to a depth of 2.5m, 10 times this depth is 25m, making option A the correct choice.

Question 13

The On Site Guide states that T.T TN-S and TN-C-S systems have the following max Ze values

Accepted Answer

According to the On Site Guide, the maximum Ze values for T.T, TN-S and TN-C-S systems are T.T. 21â„¦, TN-S 0.8â„¦ and TN-C-S 0.35â„¦. Therefore, option D is the correct answer.

Question 14

Where BS 7671 show a protective device as having a maximum Zs value of 2.3O the maximum corrected value will be

Accepted Answer

According to the formula Zs=Uo/(k*In), the maximum corrected value of Zs will be 1.84 ohms for a protective device with a maximum Zs value of 2.3 ohms, assuming a 230V supply voltage and a 0.8 power factor. Therefore, the best choice is B.

Question 15

A BS EN 61008-1 RCD is to be installed on a farm to provide fire protection, The maximum Iâˆ†n rating for the device would be

Accepted Answer

The correct I∆n rating for a Residual Current Device (RCD) intended for fire protection on a farm, according to BS EN 61008-1, is 300 mA. This rating is chosen to balance sensitivity to fault currents that could cause fires with avoiding nuisance tripping from normal farm operations.

Question 16

The maximum disconnection time permissible for a BS EN 61008-1 RCD used for fire protection is

Accepted Answer

BS EN 61008-1 RCDs used for fire protection have a maximum disconnection time of 300ms.

Question 17

The maximum permitted disconnection time for a 20A radial circuit connected to a TN-S system is

Accepted Answer

In a TN-S system, the maximum disconnection time for a final circuit not exceeding 32A is 0.4 seconds to ensure safety and prevent electric shock.

Question 18

A circuit is which is 30 m long ins wired in copper conductors each of which have a resistance value of 7.41mâ„¦/m at 20 deg C. Calculate the expected voltage drop for this circuit if a load of 16 A is connected to it

Accepted Answer

The answer of A circuit is which is 30 m...

Question 19

Voltage drop can be verified using either of two methods, these are

Accepted Answer

The most accurate and reliable way to verify voltage drop is by measuring the circuit impedance and then using it to calculate the expected voltage drop. Enquiry and testing may not provide accurate results, and tables may not account for variations in conditions.

Question 20

To comply with recommendations provided by the HSE safe isolation should be carried out using

Accepted Answer

An approved voltage indicator is the best choice for safe isolation as it is recommended by the HSE and is specifically designed for this purpose. A proving unit can be used to check the accuracy of the voltage indicator, but it is not necessary for safe isolation. A volt stick is not recommended by the HSE as it may not give an accurate reading and does not allow for the testing of phase-to-phase voltage. A multi-meter can be used for voltage testing, but it is not designed specifically for safe isolation and may not provide the necessary level of protection.

Quiz 6: Completion of Test Certiﬁcates