NEC practice quiz

In any anesthetizing location, all metal raceways and metal-sheathed cable and all normally non-current-carrying conductive portions of fixed electric equipment must be connected to ____________.

• listed sealing devices

• an equipment grounding conductor

• strain-relief devices

• low-voltage transformers

Answer explanation

517.62

The three branches of a health care facility system are :

I. life safety , critical, grounded

II. critical, lighting, life safety

III. life safety, critical, equipment

IV. high voltage, low voltage , communications

• I.

• II.

• III.

• IV.

Answer explanation

517.31 (A)

A 20,000 ft square office building is served by a 480 Y/277 V, three-phase service. The building contains the following loads.

Calculate the total feeder load:

10,000 VA, 208 V, three-phase sign

100 duplex receptacles supplying continuous loads rated 180 VA each

30 ' long show window

12 kVA, 208Y/120V three-phase electric range

10 kVA, 208Y/120V three-phase electric oven

20 kVA, 480 V three phase water heater , 7.5 hp, 480 V three-phase motor

75 -150 watt 120 V incandescent lighting fixtures, 200 - 200 VA input , 277 V fluorescent fixtures

40 kVA, 480 V three-phase electric heating unit

60 A, 480 V, three-phase air-conditioning unit

• 22,000 VA

• 51,563 VA

• 73,563 VA

• 75,633 VA

Answer explanation

1. Calculate the rec. loads - 100 x 180 VA = 18,000 VA

2. 220.44 T. first 10000 @ 100 % = 10,000 VA

3. Remaining 8,000 VA @ 50 % = 4,000 VA (14,000 VA)

4. Calculate show windows 200 VA x 30 ' = (6,000 VA )

5. Incandescent lighting 75 @ 150 VA = (11,250 VA)

6. 10 kVA sign = 10,000 VA = (10,000 VA)

7. 12 kVA range = 12,000 VA = (12,000 VA)

8. 10 kVA oven = 10,000 VA = (10,000 VA)

9. Non - Continuous loads @ 100 % =

10. Range - 12,000 VA + oven 10,000 VA = 22,0000 VA

11. Continuous loads @ 125 % =

12. Receptacles - 14,000 VA + Show window 6,000 VA + Lighting 11,250 VA + Sign 10,000 VA = 41,250 VA x 125 % = 51,563

13. Total Feeder load = Non-Cont. + Cont. = 22,000 VA + 51,563 =

14. 73,563 VA

The field windings of an AC generator are located on the ________.

• generator rotor

• generator stator

• generator transfer switch

• generator exciter

A timing relay that provides the timed dely after the relay is energized is called a(n)

• on-delay relay

• off-delay relay

• delay-on-break relay

• timed-closed relay

A current transformer __________ a single-phase transformer.

• can never be

• considers a high kVA

• is a isolation type of

• is always

The symbol in the diagram represents a(n)

• motor overload

• triac

• light emitting diode

• photo cell

What is the likely cause of the neutral damage in the diagram?

• unbalanced current

• double tapping

• under-sizing

• incorrect torque

Seals for hazardous locations are typically rated for _______ % fill.

• 25

• 50

• 60

• 100

In a circuit supplying power to inductive load, Current waveform leads the voltage waveform:

• true

• false

• sometimes

• never