EWRB EXAM QUESTIONS 63 AND ANSWERS WITH
COMPLETE SOLUTIONS LATEST UPDATE
In New Zealand, the standard distribution system has the neutral conductor connected to the earth at
the main switchboard on all low voltage installations. What name is given to this type of system?
Multiple Earthed Neutral or MEN system.
State the test voltage used for carrying out an insulation resistance test on three-phase, 400V,
electrical equipment incorporating MIMS elements.
500v dc
State one reason why the resistance of the protective earthing conductor of a flexible cord for a Class I
electrical appliance is set at a maximum of 1 Ω
Under fault conditions, it prevents the touch voltages rising to dangerous levels.
To ensure sufficient fault current flows to operate the protective device
State one factor that determines the voltage drop in a 400V, final subcircuit TPS cable.
Type of conductor material
Cross-sectional area
Load
Length of cable
, An isolator for 230V electrical equipment has been replaced. During the work the phase (active) and
neutral were accidentally transposed at the supply side of the isolating switch. What potential danger
would this transposition create?
The internal circuitry of the electrical equipment would be live when the isolating switch is in the OFF
position
A voltage test for isolation is being carried out on a three-phase, 400V oven that may or may not be
live. State the main safety issue that would occur if the only testing done was between each phase.
One phase could still be alive.
List two types of earth electrode that may be used to connect an MEN system to the mass of earth.
Earth rod
Buried electrode
Metallic reinforcing
Earth mat
State what is meant by the term current rating as it applies to an HRC fuse?
This is the maximum current that the fuse is designed to carry continuously
State one reason why an RCD tester is used to test a PRCD.
To verify that the PRCD operates within specified residual current limits.
To verify that the PRCD operates within specified time limits
A three-phase induction motor is controlled by a star/delta starter that incorporates thermal
overloads.
COMPLETE SOLUTIONS LATEST UPDATE
In New Zealand, the standard distribution system has the neutral conductor connected to the earth at
the main switchboard on all low voltage installations. What name is given to this type of system?
Multiple Earthed Neutral or MEN system.
State the test voltage used for carrying out an insulation resistance test on three-phase, 400V,
electrical equipment incorporating MIMS elements.
500v dc
State one reason why the resistance of the protective earthing conductor of a flexible cord for a Class I
electrical appliance is set at a maximum of 1 Ω
Under fault conditions, it prevents the touch voltages rising to dangerous levels.
To ensure sufficient fault current flows to operate the protective device
State one factor that determines the voltage drop in a 400V, final subcircuit TPS cable.
Type of conductor material
Cross-sectional area
Load
Length of cable
, An isolator for 230V electrical equipment has been replaced. During the work the phase (active) and
neutral were accidentally transposed at the supply side of the isolating switch. What potential danger
would this transposition create?
The internal circuitry of the electrical equipment would be live when the isolating switch is in the OFF
position
A voltage test for isolation is being carried out on a three-phase, 400V oven that may or may not be
live. State the main safety issue that would occur if the only testing done was between each phase.
One phase could still be alive.
List two types of earth electrode that may be used to connect an MEN system to the mass of earth.
Earth rod
Buried electrode
Metallic reinforcing
Earth mat
State what is meant by the term current rating as it applies to an HRC fuse?
This is the maximum current that the fuse is designed to carry continuously
State one reason why an RCD tester is used to test a PRCD.
To verify that the PRCD operates within specified residual current limits.
To verify that the PRCD operates within specified time limits
A three-phase induction motor is controlled by a star/delta starter that incorporates thermal
overloads.
