Assessment of General Characteristics

What is the first step in assessing general characteristics according to BS 7671?

• ASelecting cables
• BDetermining the purpose of the supply and intended use✓
• CInstalling protection devices
• DTesting the installation

Answer: The purpose, loads, and intended use must be determined before design decisions can be made.

What does 'external influences' assessment include?

• AVoltage only
• BEnvironmental conditions, mechanical hazards, and human factors✓
• CCable color selection
• DThe phase rotation only

Answer: External influences assessment covers temperature, humidity, corrosive atmosphere, mechanical damage risk, and other environmental factors.

In BS 7671, what is meant by 'compatibility'?

• AThe ability to use different manufacturers' equipment
• BThe suitability of equipment and protective devices to work safely together✓
• CMatching cable colors
• DUsing the same gauge throughout

Answer: Compatibility ensures that all components of an installation work together safely and effectively.

What aspect of maintainability must be considered during design?

• ACost of maintenance only
• BEase of inspection, testing, and repair✓
• CWarranty duration
• DSupplier availability

Answer: An installation must be designed to allow safe and practical maintenance, inspection, and testing.

How should an installation be designed regarding accessibility?

• AAll components must be visible
• BAccess should allow safe operation, inspection, and maintenance✓
• CEquipment must be on the ground
• DNothing should be above shoulder height

Answer: Design must ensure that components are accessible for safe operation, inspection, maintenance, and testing.

What is a key consideration when assessing the electrical demand of an installation?

• AThe number of rooms only
• BThe maximum simultaneous load demand✓
• CThe type of flooring
• DThe building age only

Answer: Maximum simultaneous demand must be determined to correctly size cables, protective devices, and the supply.

In assessing general characteristics, what is 'diversity'?

• AUsing different types of cables
• BThe probability that not all loads operate simultaneously at full capacity✓
• CHaving multiple suppliers
• DThe number of circuits

Answer: Diversity accounts for the fact that not all loads typically operate at maximum simultaneously.

What must be established regarding the continuity of supply?

• AWhether backup power is available
• BWhether the installation has a UPS only
• CWhat level of supply continuity is required for critical functions✓
• DNothing; all supplies are equal

Answer: The required level of supply continuity must be determined for different parts of the installation.

How should an installation be assessed for safety systems?

• AOnly examine fire alarms
• BReview all safety-critical systems and their electrical requirements✓
• CIgnore electrical safety systems
• DAssess the main switch only

Answer: Safety systems such as emergency lighting, fire alarms, and emergency shutdown systems must be assessed.

What is the significance of assessing 'special requirements' in BS 7671?

• AOnly applies to industrial sites
• BIdentifies areas needing enhanced protection (bathrooms, swimming pools, etc.)✓
• CApplies to color coding only
• DIs optional

Answer: Special requirements are assessed to identify areas like bathrooms and hazardous zones needing additional protection.

When assessing general characteristics, why is earthing system type critical?

• AIt determines conductor color
• BIt affects the choice of protective devices and bonding requirements✓
• CIt only matters for three-phase systems
• DIt has no impact on design

Answer: The earthing system type determines RCD requirements, bonding conductor sizing, and protective device coordination.

What should be documented during the assessment of general characteristics?

• AOnly the cable sizes
• BThe designer's name and date only
• CAll design decisions, assumptions, and assessment outcomes✓
• DNothing; verbal agreements suffice

Answer: All assessments and design decisions must be documented for traceability and future reference.