Regs-Part 4- Chapter 41.

Using the regulations, what would be the MAXIMUM disconnection time for a 230v single-phase AC TN system?

• 0.8

• 0.4

• 1

• 0.2

Answer explanation

Table 41.1, page 65 shows the maximum disconnection times for Systems. the Column 12v-230v shows the TN disconnection time as 0.4

Using the regulations, what is the maximum earth fault loop impedance (Zs) for a BS 88-2, 16A fuse serving a 230v final circuit?

• 2.43

• 45

• 1.68

• 30

Answer explanation

The maximum Zs for fuses serving final circuits (which will have a maximum 0.4s disconnection time) can be found in table 41.2 page 67.

Using the regulations, what is the maximum earth fault loop impedance (Zs) for a BS 88-3, 32A fuse serving a 230v distribution circuit?

• 1.6

• 0.55

• 6.8

• 3.9

Answer explanation

The maximum Zs for a fuse serving a single phase distribution circuit (which has a maximum disconnection time of 5s) can be found in table 41.4 page 69.

Which of the following are provisions for basic protections?

• Barriers or enclosures

• Basic insulation of live parts

• Obstacles and placing out of reach

• Main protective bonding conductors

Answer explanation

Regulation 416 'Provisions for basic protection' page 80 lists the provisions. Main protective bonding conductors are a provision for 'Protection against fault current'.

A person touches a metallic light switch and gets an electric shock. Which of the following is correct?

• Indirect contact shock

• Direct contact shock

Answer explanation

Indirect contact occurs when someone touches a part which is not normally live. It becomes live due to a fault in the electrical installation or appliance. For example, failure of the electrical insulation between a live part and the metal casing of an appliance would cause the casing to become live. This relate to REGULATION 416.1 'Basic insulation of live parts'.

Using the regulations, a horizontal top surface of a barrier or enclosure which is readily accessible shall provide a degree of protection of at least...

• IPXXD or IP4X

• IPXXB or IP2X

• IPX6

• IP65

Answer explanation

Regulation 416.2.2 page 80.

Classification of external influences are found in Appendix 5 of the regulations.