Electrical Safety Quiz

After the occurrence of a first fault, what conditions for automatic disconnection of supply in the event of a second fault occurring on a different live conductor shall be followed where the neutral conductor is not distributed in AC systems and in DC systems where the midpoint conductor is not distributed?

• Zs ≤ U0 / 2Ia

• Zs ≤ U0 x Cmin / Ia

• Zs' ≤ U0 x Cmin / 2Ia

• Zs ≤ U0 / Cmin

What is the factor taken into account by the formula Zs ≤ U0 / 2Ia for conditions after the occurrence of a first fault?

• The impedance changes due to temperature variations

• The event of the simultaneous occurrence of two faults

• The resistance of the protective conductor

• The voltage variations depending on time and place

For the exposed-conductive-parts that are earthed in groups or individually, what is the condition that applies for automatic disconnection of supply?

• RA x Ia ≤ 50 V

• RA + Ia ≤ 50 V

• RA / Ia ≤ 50 V

• RA - Ia ≤ 50 V

What does FELV stand for?

• Functional extra-low voltage

• Fundamental electrical low voltage

• Fixed equipment low voltage

• Final extra-low voltage

Under what conditions is FELV used?

• Where a nominal voltage not exceeding 50 V AC or 120 V DC is used and all the requirements of SELV or PELV are fulfilled

• Where a nominal voltage not exceeding 50 V AC or 120 V DC is used but not all the requirements of SELV or PELV are fulfilled

• Where a nominal voltage exceeding 50 V AC or 120 V DC is used and all the requirements of SELV or PELV are fulfilled

• Where a nominal voltage exceeding 50 V AC or 120 V DC is used but not all the requirements of SELV or PELV are fulfilled

According to Regulation 411.7.2, basic protection for a FELV system can be provided by which of the following methods?

• Insulation according to Regulation 416.1 corresponding to the nominal voltage of the primary circuit of the source

• Barriers or enclosures in accordance with Regulation 416.2

• Automatic disconnection of supply

• Use of a residual current device (RCD)

What is the maximum nominal voltage of the reduced low voltage circuits according to Regulation 411.8.1.2?

• 110 V AC between lines

• 63.5 V to earthed neutral, single-phase

• 55 V to earthed midpoint

• 220 V AC between lines

What must every plug, socket-outlet, luminaire supporting coupler (LSC), device for connecting a luminaire (DCL), and cable coupler in a FELV system have according to Regulation 411.7.5?

• A protective conductor contact

• Compatibility with those used for any other system in the same premises

• A residual current device (RCD)

• An automatic disconnection of supply

What is the required action for fault protection in reduced low voltage systems as per Regulation 411.8.3?

• Insulation of live parts

• Automatic disconnection of supply by means of an overcurrent protective device

• Installation of barriers or enclosures

• Connection to a transformer with at least simple separation between windings

According to Table 4.16, what is the maximum earth fault loop impedance (Zs) in ohms for a 10-ampere B-type circuit-breaker at 55 volts?

• 1.05

• 1.21

• 0.52

• 0.60