Licensed Electrical Contractor Electrical Contractor Electrical System Design & Installation 2

Question 1

When designing a commercial electrical system, what is the NEC-required minimum height for service entrance conductors over a public roadway?

Accepted Answer

18 feet

Answer

15 feet

Answer

12 feet

Answer

10 feet

Question 2

In a 208/120V three-phase, four-wire wye system, what is the voltage measured between any two phase conductors?

Accepted Answer

208V

Answer

120V

Answer

240V

Answer

277V

Question 3

What is the maximum allowable voltage drop recommended by the NEC for a combination of feeder and branch circuit conductors?

Accepted Answer

5%

Answer

3%

Answer

8%

Answer

10%

Question 4

When installing a 400-amp service in a commercial building, what is the minimum size copper conductor required for the grounding electrode conductor?

Accepted Answer

1/0 AWG

Answer

2 AWG

Answer

3/0 AWG

Answer

250 kcmil

Question 5

What type of electrical system grounding is required by the NEC for a 480/277V, three-phase, four-wire system supplying a commercial building?

Accepted Answer

Solidly grounded

Answer

Ungrounded

Answer

Resistance grounded

Answer

Corner grounded

Question 6

Per NEC Article 220, what is the general lighting load demand factor applied to the first 10,000 VA of general lighting in a commercial occupancy?

Accepted Answer

100%

Answer

50%

Answer

75%

Answer

125%