E2 Systems and Equipment 2

Question 1

According to the NEC, what is the minimum clearance required above a switchboard in a commercial installation?

Accepted Answer

6 feet

Answer

3 feet

Answer

6.5 feet

Answer

8 feet

Question 2

A commercial building's emergency lighting system is required to provide illumination for at least how long upon loss of normal power?

Accepted Answer

90 minutes

Answer

30 minutes

Answer

60 minutes

Answer

120 minutes

Question 3

When inspecting a variable frequency drive (VFD) installation, which conductor issue is most critical to verify?

Accepted Answer

Conductor ampacity derating for harmonic heating

Answer

Wire insulation color

Answer

Use of aluminum conductors only

Answer

Minimum 10 AWG branch circuit

Question 4

Under the NEC, a motor controller must be capable of interrupting the stalled-rotor current of the motor it controls. This rating is known as the:

Accepted Answer

Locked rotor current (LRC)

Answer

Full load current (FLC)

Answer

Service factor amperage

Answer

Running overload rating

Question 5

In a commercial kitchen, a dishwasher is hardwired to a 20-ampere, 120-volt circuit. The NEC requires this circuit to be protected by a:

Accepted Answer

Standard GFCI breaker

Answer

AFCI breaker

Answer

GFCI with 4mA trip threshold

Answer

Standard overcurrent device only

Question 6

What does the NEC require for grounding electrode conductors at a commercial service entrance that uses a metal water pipe as a grounding electrode?

Accepted Answer

A supplemental electrode must also be installed

Answer

The conductor must be at least 4 AWG copper

Answer

The pipe must be bonded with a 6 AWG conductor only

Answer

No supplemental electrode is needed if the pipe is 3/4 inch or larger

Question 7

A rooftop HVAC unit on a commercial building is served by a disconnect switch mounted on the unit. The NEC requires this disconnect to be:

Accepted Answer

Lockable in the open position

Answer

Rated at 200% of the motor FLA

Answer

Located inside the unit's electrical compartment

Answer

A fused safety switch only