012 Sample Evolve questions (A)

Which of the following should an instrument comply with when testing a 230v single phase installation?

• BS EN 61010

• HSE GS 38

• HSE GN3

• BS EN 60309-2

Answer explanation

HSE GS 38 outlines safety guidelines for electrical testing instruments, ensuring they are suitable for use in 230v single phase installations. This makes it the correct choice for compliance in this context.

Which test confirms BS 7671 for ADS have been met?

• Earth fault loop impedance

• Prospective Fault current

• RCD Test

• Phase rotation

Answer explanation

The Earth fault loop impedance test confirms that the requirements of BS 7671 for Automatic Disconnection of Supply (ADS) are met, ensuring safety by verifying the effectiveness of the earthing system.

Which of the following is the purpose of the integral test button on an RCD?

• To confirm function of mechanical parts

• To ensure it disconnects at the specified current

• To isolate the RCD prior to carrying out instrument tests

• To test the RCD

Answer explanation

The integral test button on an RCD is primarily used to confirm the function of mechanical parts, ensuring that the device operates correctly when needed. This is crucial for safety and reliability.

Which one is used to establish phase sequencing for an installation?

• Frequency meter

• Power factor indicator

• Rotating disk instrument

• EFLI Tester

Answer explanation

A rotating disk instrument is specifically designed to establish phase sequencing by indicating the direction of rotation, which helps in determining the correct phase sequence for electrical installations.

The breaking capacity of a protective device must

• Exceed the IPF

• Exceed PEFC but not PSCC

• Not exceed IPF

• Not exceed PEFC but exceed PSCC

Answer explanation

The breaking capacity of a protective device must exceed the IPF (Initial Prospective Fault Current) to ensure it can safely interrupt fault currents without failure, making 'Exceed the IPF' the correct choice.

Having completed a test of prospective fault current at the origin of an installation, the results should be compared to?

• Breaking capacity of the main protective device

• Breaking capacity of the main isolator

• Nominal current rating of the main protective device

• Nominal voltage

Answer explanation

The results of the prospective fault current test should be compared to the breaking capacity of the main protective device to ensure it can safely interrupt the fault current without failure.

The prospective fault current for a single phase electrical installation is measured between line - earth and line – neutral. The reading on the certificate is

• Line – earth

• Line – Neutral

• Highest value of the two

• Lowest value of the two

Answer explanation

The prospective fault current is determined by measuring both line-earth and line-neutral. The highest value of the two readings indicates the maximum fault current that could occur, making 'Highest value of the two' the correct choice.

PEFC and PSCC where measured at 0.7KA and 1.2KA, which is recorded as PFC

• 1.2KA

• 0.7KA

• 1.9KA

• 0.5KA

Answer explanation

The PFC (Power Factor Correction) is determined by the higher value between PEFC and PSCC. Since 1.2KA (PSCC) is greater than 0.7KA (PEFC), the correct answer is 1.2KA.

The maximum tabulated EFLI value for a prospective device is 1.37ohms. The maximum value of EFLI permitted for the circuit is

• 0.9

• 1.09

• 1.370

• 2.167

Answer explanation

The maximum EFLI value of 1.37 ohms indicates the device's resistance. The permitted maximum for the circuit is typically lower, hence 1.09 ohms is the correct choice, ensuring safety and compliance.

If the max tabulated EFLI is 2.73ohms then the maximum permitted EFLI for the circuit will be

• 3.4

• 2.7

• 2.1

• 2

Answer explanation

The maximum permitted EFLI is typically set lower than the max tabulated value to ensure safety. Therefore, with a max EFLI of 2.73 ohms, the maximum permitted value is 2.1 ohms, making it the correct choice.