Questions 241 - 260 Review (309A 2015) : 14-104 Rating of Overcurrent Devices (See Appendix B)
Questions 241 - 260 Review (309A 2015) : 14-104 Rating of Overcurrent Devices (See Appendix B)
Questions 241 - 260 Review (309A 2015) : 14-104 Rating of Overcurrent Devices (See Appendix B)
241. What is the maximum ampacity for a #12 awg in a commercial lighting system?
a. 15 c. 25
b. 20 d. 30
ANS: B
(1) The rating or setting of overcurrent devices shall not exceed the allowable ampacity of
the conductors that
(a) where a fuse or circuit breaker having a rating or setting of the same value as the
ampacity of the
conductor is not available, the ratings or settings given in Table 13 shall be permitted to be
used
(b) in the case of equipment wire, flexible cord in sizes Nos. 16, 18, and 20 AWG copper, and
tinsel cord,
PTS: 1
242. When wiring a signal circuit for a supervised fire alarm system, you will be connecting
ANS: C
Signal circuits are circuits on the output of the fire alarm system such as siren, strobes, bells,
horns. They all have diodes in them.
PTS: 1
243. What is the maximum length in meters of an emergency lighting system that is 12 V
and is required to supply 8 lamps that are 6 W each with a maximum of 5% voltage
drop when using a #10 AWG conductor?
a. 36.5 m c. 22.9 m
b. 29.4 m d. 18.7 m
ANS: C
TD4 is the 4th table in Appendix D. The formula is L=((V/6)x(voltage drop given/5)x(It/I)xLt).
The actual wattage is calculated as (8 lamps X 6 Watts)= 48W. The actual current is
(48W/12V)=4A. The length is ((12/6)x(5/5)x(4.25/4)x10.8)=22.9m
PTS: 1
244. What is the minimum size of box for a light fixture which has a 16 gauge wire coming
from the fixture that is being fed by a #14 awg conductors in the box?
ANS: A
The 16 gauge wire do not count since they are not a part of table 23. We are looking for the
minimum size of box that will hold 2 #14 gauge wire. Using table 23, we choose 4 x 1-1/2
Octagonal.
PTS: 1
245. When the trouble buzzer is ringing on a supervised fire alarm system it means that
A pull station has been activated A wire has come loose from its
a. c.
falsely connection
The end -of-line resistor is of the An automatic alarm-initiating
b. d.
wrong value device has been activated
ANS: C
The trouble buzzer rings either because of a broken or loose wire or the pressure in the
sprinkler system is low.
PTS: 1
246. When communication conductors are directly-buried in a trench with other directly-
buried system and the communication cables do not have a metal sheath, the
minimum separation between the communication cables and the other system must
be
a. 300 mm c. 900 mm
b. 600 mm d. 1 m
ANS: A
300mm. Search the index page 673, communication conductors-underground. Rule 60-
600
PTS: 1
247. A flow transmitter has an input range of 40 gallons per minute(GPM) to 130 GPM, using
a standard output signal of 10 to 50 mA. If the output signal is 27.8 mA, what is the flow
rate?
ANS: B
The 40 Gpm to 130 Gpm is a 90 step scale. The 10ma to 50ma is a 40 step scale. We need to
calculate the ratio of the 90 step scale to the 40 step scale. Therefore, 90/40=2.25. This
means the 90 step scale is 2.25 times bigger than the 40 step scale. So every time we climb
the 40 step scale by one step, we climb the 90 step scale by 2.25 steps. If the output signal is
27.8ma on the 40 step scale and this scale starts on the 10th step, then the actual output
signal is 17.8ma (27.8ma-10ma). So (17.8×2.25)=40 steps. The 90 step scale starts at step 40
so we add the 40 that we calculated to starting step of the 90 step scale. 40+40=steps (80
Gpm)
PTS: 1
248. The transformer illustrated below is a 10:1 step-down transformer and is connected to
a 120V supply. What value of volts will the voltmeter indicate when it is connected in
this manner? Diagram 18.
a. 24 V c. 12 V
b. 132 V d. 108 V
ANS: D
This is a step down transformer. It steps down on the phase voltage. The 120V on the primary
is 10 times greater than the secondary. Therefore, 120V/10=12V. Since the voltmeter is across
terminals H1 and X1, the transformer has a subtractive polarity. The voltmeter will read 108V
(120V-12V).
https://electricalexamreview.com/wp-content/uploads/2018/04/442A-spare-39.png
(https://electricalexamreview.com/wp-content/uploads/2018/04/442A-spare-39.png)
PTS: 1
ANS: A
PTS: 1
250. If a hot water tank that is rated for 5,000 watts at 240 V AC single-phase was hooked
up incorrectly to a 120V supply, the power of the circuit would be
a. 5,000 W c. 1,250 W
b. 2,500 W d. 0 W
ANS: C
Since the voltage drops from 240V to 120V, the wattage drops by 4. (5000w/4)=1250W. On
the other hand, if the voltage doubles from 120V to 240V, the wattage would quadruple.
PTS: 1
251. You are performing a field-assembled connection between an aluminum lug and a
copper bus bar using a 10 mm bolt. To allow for expansion of the connection you must
also include
Flat and helical washers (lock washers) are assembled together to lock two parts tightly
together. To allow for expansion, only conical washers are used with nothing else.
PTS: 1
252. An apartment will install an electric baseboard heater that is supplied at 25A/240V.
The heater is 45m away from the distribution panel. What size of R90 conductor should
be used without exceeding 3% voltage drop?
a. 14 c. 10
b. 12 d. 8
ANS: D
PTS: 1
253. Which of the following diode is suitable replacement of the faulty 10A 25V diode?
ANS: C
We need a diode that is the same size and not lower than 10A and 25V.
PTS: 1
254. A motor is presently protected by a 30A NTD fuse that keeps blowing upon starting. A
NTD fuse is to be used. Select the correct size as shown below.
ANS: B
A NTD fuse is to be used and the 30A fuse keeps blowing, therefore we need to use the 40A
NTD fuse.
PTS: 1
255. Calculate the basic load requirements for 186 m² single family residential home that
will be part of and will be determining the total calculated load
a. 3000W c. 6000W
b. 4000W d. 7000W
ANS: D
Rule 8-200.
186mm2-90mm2 5000W
96mm2-90mm2 1000W
6mm2 1000W
Total 7000W
PTS: 1
ANS: B
#8awg is a stranded conductor. From size #8awg and up, we strand the wires and use lugs
and bushings.
PTS: 1
a. 347V c. 200V
b. 230V d. 208V
ANS: A
PTS: 1
ANS: B
PTS: 1
a. Tie it up c. Replace it
b. Sew it back together d. Put it back for someone else to use
ANS: C
Replace it.
PTS: 1
260. PPE required for a hammer drill
a. Boots, glasses, hard hat, coveralls c. Boots, glasses, hard hat, ear plugs
Boots, gloves, glasses, hard hat, dust
b. d. Boots, hard hat, ear plugs
mask
ANS: B
It is the level and duration of noise that decides the type of Personal Protection Equipment
that we use. We use hammer drills to drill holes in concrete. The duration is not a concern.
The concrete contains silica (sand). We need to protect our lungs from the concrete dust
with a dust mask.