WorksheetsPhilippine Electrical Code (Subject 6) - Nth
Total questions: 50
Worksheet time: 50mins
1.The highest current rating of an Edison-base plug fuse is:
30 amperes
60 amperes
100 amperes
200 amperes
2. Edison-base plug fuses may be used only in:
New work
Existing installations under specified conditions
Motor control panels
Motor circuits
3. Which of the following is a nonstandard ampere rating for a plug fuse?
15 amperes
20 amperes
30 amperes
35 amperes
4. The maximum size fuse allowed to protect a No. 14 AWG THW conductor is:
10 amperes
15 amperes
20 amperes
25 amperes
5. When a circuit breaker trips, its operating handle will be in which of the following positions?
Closed (energized) position
Open position
Half-way between the ON and OFF positions
No change
6. Plug fuses of 15 ampere and lower rating must be identified by what type of window configuration?
Round
Hexagonal
Square
Octagonal
7. Which of the following conductors need overcurrent protection on a residential electric service?
Grounded conductor
Bonding conductor
Ungrounded conductors
Equipment grounding conductor
8. A circuit feeding three single-phase motors with full-load current ratings of 40, 20 and 20 amperes, respectively, requires the following dual-element time-delay fuse size:
110 amperes
150 amperes
200 amperes
250 amperes
9. A nontime-delay fuse protects a circuit with all motor loads with the largest motor drawing a full-load current of 40 amperes, and two other motors drawing a full-load current of 15 amperes
each. What fuse size should be used?
100 amperes
150 amperes
175 amperes
250 amperes
10. An “AFCI receptacle” is known as a(n):
Arc resistant outlet
Upstream parallel arc fault protector
Branch circuit-type AFCI
Combination device
11. Conductors may be tapped, without overcurrent protection at the tap, to a feeder or transformer secondary if certain conditions are met. If the ampacity of the tap conductor is not less than the combined computed loads on the circuits supplied by the tap conductor, the length of the tap conductor cannot exceed:
5 feet
10 feet
15 feet
25 feet
12. Where must an overcurrent device be located in a circuit?
At the point where the conductor receives its supply
At the last outlet on the circuit
On the line side of the electric meter
At the first fitting or connector in the circuit
13. If a multiwire branch circuit supplies line-to-line loads, the branch-circuit protective device must open each:
All ungrounded conductors simultaneously
Grounded conductor
Ungrounded conductor individually
Bonding conductor
14. The largest standard rating for fuses and inverse time circuit breakers is:
1000 amperes
1600 amperes
1200 amperes
6000 amperes
15. To meet NEC regulations, fuses or circuit breakers connected in parallel must be:
Assembled by the electrician or technician on the job
Encased in a PVC housing
Factory assembled in parallel
Rated over 200 amperes
16. Supplementary overcurrent devices shall:
Be required to be readily accessible and within sight of the equipment
Not be required to be readily accessible
Not be allowed under any conditi
Be connected only in parallel or series-parallel configurations
17. One combination that is considered by the NEC to be equivalent to an overcurrent trip unit is:
Pole-mounted transformer and overcurrent relay
Submersible transformer and overcurrent relay
Autotransformer and overcurrent relay
Current transformer and overcurrent relay
18. When a fuse or circuit breaker is used for circuit protection, the fuse or overcurrent trip unit shall be connected:
In series
In series and parallel
In parallel
In tandem
19. At what point must a branch-circuit overcurrent protection device be placed in an electrical system?
At the equipment ground location
Where the conductor being protected receives its supply
At a tap on the conductor being protected
At the outlet where power is consumed
20. The rating of the overcurrent protective device for a circuit supplying a hermetic motor compressor must be at least what percent of the nameplate rated-load current?
50%
75%
115%
150%
21. A multiwire branch circuit protected by fuses may supply only:
Half line to line loads and half line to neutral loads
Half line to neutral loads to full or trip line to other loads
Line to line loads
Line to neutral loads
22. What is the minimum interrupting rating of an unmarked branch-circuit fuse?
5,000 amperes
10,000 amperes
15,000 amperes
20,000 amperes
23. A feeder tap less than 25 feet long does not require overcurrent protection at the tap if the ampacity of the tap conductor is at least:
50% of the feeder conductor
40% of the feeder conductor
33 1/3% of the feeder conductor
20% of the feeder conductor
24. When designing or installing circuits for diagnostic equipment in health care facilities, what is the minimum percentage allowed for the momentary ampacity of the equipment when sizing
branch-circuit conductors and the overcurrent protection?
25%
50%
75%
100%
25. The rated ampacity of conductors and overcurrent devices of a feeder for two or more branch circuits supplying X-ray equipment for non-medical or non-dental use must not be less than 100% of the momentary demand rating of the two largest pieces of X-ray equipment plus what percent of the momentary ratings of other X-ray apparatus?
5%
10%
15%
20%
26. What is the maximum overcurrent device rating for each resistance welder connected to an electrical system?
Not over 100% of the rated primary current of the welder
Not over 200% of the rated primary current of the welder
Not over 300% of the rated primary current of the welder
Not over 400% of the rated primary current of the welder
27. What is the maximum overcurrent device rating that may be used for each AC transformer or DC rectifier arc welder?
Not over 100% of the rated primary current of the welder
Not over 200% of the rated primary current of the welder
Not over 300% of the rated primary current of the welder
Not over 400% of the rated primary current of the welder
28. Each autotransformer 600 volts, nominal, or less shall be protected by an individual overcurrent device. How must this device be connected in relation to the autotransformer?
In parallel with each ungrounded input conductor
In parallel with each grounded conductor
In series with each ungrounded input conductor
In series with each grounded conductor
29. Such overcurrent devices as described in previous question must have a rating not exceeding a certain percentage of the rated full-load input current of the autotransformer. What is this
percentage?
110%
125%
150%
200%
30. If an autotransformer has a full-load input current of 40 amperes, what is the maximum overcurrent protection device rating allowed?
45 amperes
50 amperes
60 amperes
70 amperes
31. In an autotransformer, overcurrent devices shall not be installed:
In parallel with the output conductors
In parallel with the shunt winding
In series with the output conductors
In series with the shunt winding
32. grounding autotransformer is used to create a three-phase, 4-wire distribution system from a three-phase, 3-wire ungrounded system. At what percent must the overcurrent device be set to trip in case of an overload?
100% of the transformer’s continuous current per phase or neutral rating
110% of the transformer’s continuous current per phase or neutral rating
125% of the transformer’s continuous current per phase or neutral rating
150% of the transformer’s continuous current per phase or neutral rating
33. What must the continuous neutral current rating be for an autotransformer used to create a three-phase, 4-wire distribution system from a three-phase, 3-wire ungrounded system?
It must be sufficient to handle the minimum neutral unbalanced load
It must be sufficient to handle the maximum possible neutral unbalanced load
It must be sufficient to handle 75% of the neutral unbalanced load
It must be sufficient to handle 50% of the unbalanced load
34. What is the maximum overcurrent rating that may be used for dimmer controls for stage lighting in theaters?
100% of the dimmer rating
110% of the dimmer rating
125% of the dimmer rating
150% of the dimmer rating
35. If a dimmer control is rated at 2000 watts on a 120-volt single-phase circuit, what is the maximum overcurrent protection allowed for this dimmer?
15 amperes
20 amperes
30 amperes
40 amperes
36. What is the maximum overcurrent protection allowed on circuits feeding stage equipment such as footlights, border lights, etc?
15 amperes
20 amperes
30 amperes
40 amperes
37. What is the minimum branch circuit and maximum overcurrent protection rating for a circuit supplying a household electric range rated at 8 3/4 kW or more?
20 amperes
30 amperes
40 amperes
50 amperes
38. What is the minimum number of circuits allowed to feed a household-type appliance with surface heating elements having a maximum demand of more than 60 amperes?
1
2
3
4
39. What is the maximum overcurrent protection allowed for each of the circuits described in previous question
30 amperes
40 amperes
50 amperes
60 amperes
40. What is the maximum rating of overcurrent devices used to protect circuits feeding infrared lamp heating appliances in commercial and industrial applications?
30 amperes
40 amperes
50 amperes
60 amperes
41. How must direct-current conductors used in electroplating systems be protected?
Fuses or circuit breakers
A current-sensing device that operates a disconnecting means
Other approved means by the authority having jurisdiction
Any of the above
42. Where the allowable current rating of a busway does not correspond to a standard rating of overcurrent device, what rating is permitted?
The next lower rating
No overcurrent protection is required
The next higher rating
None of the above
43. If the allowable current rating of a busway is 46 amperes, what is the maximum allowable rating of the overcurrent device?
40 amperes
50 amperes
60 amperes
70 amperes
44. Omission of overcurrent protection is permitted at points where busways are reduced in size, provided that the smaller busway length does not exceed what distance?
10 feet
20 feet
30 feet
50 feet
45. In order to comply with NEC regulations what must the current rating of the smaller busway be in previous question?
One-third the rating or setting of the overcurrent device next back on the line
Half the rating of the overcurrent device next back on the line
Three-fourths the rating of the overcurrent device next back on the line
Two-thirds the rating of the overcurrent next back on the line
46. What type of overcurrent device is required on a busway system where a branch circuit or subfeeder is tapped from the main busway?
Internally operable circuit breaker
Internally operable fusible switch
Externally operable circuit breaker or externally operable fusible switch
None is required
47. When the overcurrent devices in previous question are mounted out of reach and contain disconnecting means, what provisions must be provided for operating the disconnecting means from the floor?
Ropes
Chains
Sticks
Any of the above
48. When the allowable ampacity of a cablebus system does not correspond to a standard rating of overcurrent protection devices, what size overcurrent device is permitted?
The next lower standard size
The next higher standard size
A device not exceeding 80% of the cablebus rating
A device not exceeding 75% of the cablebus rating
49. If a cablebus system is rated at 94 amperes, what is the maximum allowable overcurrent protection device rating?
90 amperes
95 amperes
100 amperes
105 amperes
50. Mobile home disconnecting means shall be located not less than ____ above finished grade or working platform.
8 feet
2 feet
6 feet
4 feet
