18th Ed. 1

List three installations that are covered by BS 7671 and three that are not.

• Within the scope: Residential, Public premises, Prefab buildings. Outside the scope: Railway, Ships, Aircraft.

• Within the scope: Ships, Aircraft, Railway. Outside the scope: Residential, Public premises, Prefab buildings.

• Within the scope: Hospitals, Ships, Aircraft. Outside the scope: Railway, Residential, Public premises.

• Within the scope: Railway, Aircraft, Hospitals. Outside the scope: Prefab buildings, Public premises, Residential.

Answer explanation

BS 7671 covers installations like Residential, Public premises, and Prefab buildings, focusing on safety in these environments. It does not cover Railway, Ships, and Aircraft, which have their own specific regulations.

What frequencies of the supply are covered by BS 7671?

• 50Hz, 60Hz, 400Hz

• 100Hz, 200Hz, 300Hz

• 25Hz, 75Hz, 150Hz

• 120Hz, 240Hz, 360Hz

Answer explanation

BS 7671 covers standard supply frequencies of 50Hz and 60Hz, commonly used in residential and commercial settings, as well as 400Hz, which is often used in aviation and military applications.

What categories (who or what) does BS 7671 specifically name as protecting if the installation is correctly installed?

• Persons, Property, Livestock

• Vehicles, Buildings, Equipment

• Plants, Machinery, Environment

• Computers, Data, Networks

Answer explanation

BS 7671 specifically names 'Persons, Property, Livestock' as categories that are protected when the installation is correctly installed, ensuring safety and compliance in electrical systems.

What should be done if equipment does not carry a British Standard Mark?

• Other standards may be used, provided the degree of safety is no less than that of BS 7671. (These should be noted on the electrical certification document.)

• The equipment must be immediately removed from service and destroyed.

• Only equipment with a British Standard Mark can be used under any circumstances.

• The equipment can be used without any further checks or documentation.

Answer explanation

If equipment lacks a British Standard Mark, it can still be used if it meets other safety standards equivalent to BS 7671, which must be documented in the electrical certification.

Which regulation states that good workmanship and taking into account manufacturers’ instructions are a requirement?

• 134.1.1 Good workmanship and materials shall be used in the erection of electrical installations. The installation of electrical equipment shall take account of the manufacturers’ instructions.

• 411.3.2 All final circuits must be protected by a 30mA RCD.

• 522.6.202 Cables concealed in a wall or partition must be at a depth of at least 50mm.

• 514.9.1 Every installation shall have a main switch.

Answer explanation

The correct choice is 134.1.1, which explicitly states that good workmanship and materials must be used in electrical installations, and that manufacturers' instructions must be followed.

Who decides when the first periodic inspection of the installation should take place?

• The designer – Regulation 134.2.2

• The client – Regulation 135.1.1

• The inspector – Regulation 136.2.3

• The contractor – Regulation 137.3.4

Answer explanation

The designer is responsible for determining when the first periodic inspection should occur, as stated in Regulation 134.2.2. This regulation emphasizes the designer's role in ensuring compliance and safety from the outset.

Which of the following is NOT within the scope of BS 7671?

• Public premises

• Residential buildings

• Prefab buildings

• Electrical installations in ships

Answer explanation

BS 7671 covers electrical installations in public premises, residential, and prefab buildings, but it does not apply to electrical installations in ships, which are governed by different regulations.

According to BS 7671, what is the main purpose of periodic inspection and testing?

• To reduce energy consumption

• To increase the value of the property

• To ensure the safety of persons, property, and livestock

• To comply with environmental regulations

Answer explanation

The main purpose of periodic inspection and testing, according to BS 7671, is to ensure the safety of persons, property, and livestock by identifying potential hazards in electrical installations.

Which of the following frequencies is NOT covered by BS 7671?

• 50Hz

• 60Hz

• 400Hz

• 100Hz

Answer explanation

BS 7671 covers standard frequencies like 50Hz, 60Hz, and 400Hz, which are commonly used in electrical systems. However, 100Hz is not a standard frequency covered by BS 7671, making it the correct answer.

Which of the following is a key objective of BS 7671?

• To ensure the safety of persons, property, and livestock

• To regulate the cost of electrical installations

• To increase the resale value of electrical equipment

• To promote the use of renewable energy sources