Building Engineering Electrical Systems in Buildings 3

Question 1

What NEC article primarily governs the installation of emergency lighting systems in commercial buildings?

Accepted Answer

Article 700

Answer

NEC Article 700 covers emergency systems that supply illumination and power when normal power fails in occupancies required by code.

Question 2

Which type of transformer is typically used to step down 480V three-phase to 208/120V in a commercial building?

Accepted Answer

Dry-type step-down transformer

Answer

Dry-type step-down transformers are standard in commercial buildings for converting 480V distribution voltage to usable 208/120V service.

Question 3

What is meant by 'demand factor' in building electrical load calculations?

Accepted Answer

The ratio of maximum demand to total connected load

Answer

Demand factor accounts for the fact that not all connected electrical loads operate simultaneously at full capacity, allowing smaller service sizing.

Question 4

Which grounding electrode is required by NEC for all new building construction?

Accepted Answer

Concrete-encased electrode (Ufer ground)

Answer

NEC requires a concrete-encased electrode (Ufer ground) in new construction because reinforcing steel embedded in concrete provides an excellent low-resistance ground.

Question 5

What is the purpose of a power quality meter installed on a building's electrical system?

Accepted Answer

To monitor voltage, current, harmonics, and power factor continuously

Answer

A power quality meter provides real-time and historical data on voltage sags, harmonics, power factor, and demand to identify efficiency issues.

Building Engineering Practice Test

Building Engineering Practice Test

Building Engineering Electrical Systems in Buildings 3