Building Engineering Electrical Systems in Buildings 2

Question 1

What is the purpose of a transfer switch in a building's electrical system?

Accepted Answer

To switch between utility power and generator power safely

Answer

To transfer loads between phases

Answer

To step voltage up or down

Answer

To distribute power to sub-panels

Question 2

Which electrical system configuration is most common in US commercial buildings?

Accepted Answer

Three-phase 4-wire 208Y/120V

Answer

Single-phase 2-wire 120V

Answer

Three-phase 3-wire 480V delta

Answer

Single-phase 3-wire 240V

Question 3

What is the maximum allowed voltage drop for branch circuits in building electrical design per NEC recommendations?

Accepted Answer

3%

Answer

5%

Answer

10%

Answer

1%

Question 4

Which lighting control device reduces energy use by dimming lights based on available daylight?

Accepted Answer

Daylight harvesting sensor

Answer

Occupancy sensor

Answer

Time clock relay

Answer

Demand controller

Question 5

What ampacity is a standard 12 AWG copper conductor rated for in a 60°C environment per NEC?

Accepted Answer

20A

Answer

15A

Answer

25A

Answer

30A

Question 6

What is the function of a surge protective device (SPD) installed at a building's main panel?

Accepted Answer

To limit transient voltage spikes from entering building wiring

Answer

To regulate steady-state voltage

Answer

To filter harmonic distortion

Answer

To balance phase loads