Electrical Safety Regulations Quiz

What should the source of the FELV system be according to Regulation 411.7.4?

• A transformer with at least complex separation between windings

• A transformer with at least simple separation between windings

• A semiconductor device that is part of a FELV system

• A direct connection to the primary circuit without any protection

According to Regulation 411.8.1.2, what is the maximum nominal voltage of the reduced low voltage circuits?

• 110 V AC rms between lines

• 63.5 V to earthed neutral, single-phase

• 55 V to earthed midpoint, single-phase

• 55 V AC rms between lines

What is the maximum value of earth fault loop impedance (Zs) for nominal voltages of 55 V and 63.5 V with a disconnection time of 5 s as per Regulation 411.8.3?

• Specified in Table 41.6

• Calculated by the formula in Regulation 411.4.4

• Listed in the overcurrent device table

• Not specified and must be calculated for each installation

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

• A dimensionally compatible use with other system types in the same premises

• A semiconductor device

• A direct connection to the primary circuit

According to Table 4.16, what is the maximum earth fault loop impedance (Zs) in ohms for a single-phase circuit with a 63 A rating and a nominal voltage of 55 V for Type B circuit-breakers?

• 0.75 ohms

• 0.60 ohms

• 0.65 ohms

• 0.52 ohms

What is the correct value of the maximum earth fault loop impedance (Zs) for a three-phase circuit with a 10 A rating and a nominal voltage of 63.5 V for Type C and D circuit-breakers as per Table 4.16?

• 0.60 ohms

• 0.52 ohms

• 1.21 ohms

• 0.60 ohms

As per the notes in the image, what is the value of the factor Cmin used to determine the circuit loop impedances in Table 4.16?

• 0.80

• 0.95

• 1.00

• 0.90

Which of the following is NOT a source of supply to a reduced low voltage circuit as mentioned in Regulation 411.8.4?

• A double-wound isolating transformer

• An isolating transformer

• A motor-generator set having windings providing isolation

• A direct connection to a high voltage grid

What is the purpose of double or reinforced insulation as a protective measure?

• To allow any changes in the electrical circuit without supervision

• To prevent the appearance of a dangerous voltage on the accessible parts of electrical equipment

• To connect the neutral point of secondary windings of transformers to Earth

• To provide a protective contact for every plug and socket-outlet

Which of the following is NOT a requirement for the protective measure of double or reinforced insulation?

• Basic protection is provided by basic insulation

• Fault protection is provided by supplementary insulation

• It can be applied to any circuit without limitations

• It should not be applied where changes can be made without authorization