CME System Design and Installation 2

Question 1

When designing a service entrance for a commercial building, what is the minimum clearance required above a flat roof (not readily accessible) for service-drop conductors per NEC 230.24?

Accepted Answer

3 feet

Answer

8 feet

Answer

10 feet

Answer

18 inches

Question 2

A 480/277V three-phase four-wire system is being designed for a large office building. Which grounding electrode conductor size is required for a 500 kcmil copper service conductor per NEC Table 250.66?

Accepted Answer

1/0 AWG

Answer

2/0 AWG

Answer

3/0 AWG

Answer

4/0 AWG

Question 3

In a fire pump installation, what is the minimum voltage drop permitted at the motor terminals under locked-rotor conditions?

Accepted Answer

Voltage must not drop below 65% of motor nameplate voltage

Answer

5% voltage drop

Answer

Voltage must not drop below 70% of motor nameplate voltage

Answer

15% voltage drop

Question 4

When installing a paralleled conductor set for a feeder, what is the minimum conductor size permitted for each parallel conductor per NEC 310.10(H)?

Accepted Answer

2/0 AWG

Answer

3/0 AWG

Answer

1/0 AWG

Answer

250 kcmil

Question 5

A master electrician is designing a switchboard installation. Per NEC 408.18, what is the minimum headroom required in front of a switchboard?

Accepted Answer

6.5 feet

Answer

6 feet

Answer

7 feet

Answer

8 feet

Question 6

When sizing a transformer for a commercial HVAC system with a 75 kVA transformer, what is the maximum overcurrent protection device size permitted for the primary at 480V three-phase per NEC 450.3(B)?

Accepted Answer

150% of rated primary current

Answer

125% of rated primary current

Answer

200% of rated primary current

Answer

250% of rated primary current

Question 7

Which NEC article governs the design and installation requirements for emergency systems in commercial buildings?

Accepted Answer

Article 700

Answer

Article 701

Answer

Article 702

Answer

Article 708