General Use Equipment Flashcards
A 15A 0r 20A, 125V receptacle used for the reduction of electrical noise where the grounding terminal is to be isolated from the receptacle mounting yoke is required to identified by:
Having an orange triangle on the face of the receptacle
406.2(D)
This rule is covered in 250.146(D)
A dwelling has an electric range with a nameplate rating of 18.4 kW. The minimum
demand load permitted for this 120/240 volt range circuit is:
A. 33 amperes. C. 44 amperes. E. 77 amperes.
B. 43 amperes. D. 61 amperes.
**B 43 amperes
The rule for determining the minimum demand load for a dwelling electric range larger
than 12 kW is described in Note 1 of Table 220.19. The value in column C is increased
by 5% for each kW the range size is larger than 12 kW. The only trick is that the range
size is rounded off to the nearest whole number before starting. In this case, 18.4 kW is
rounded down to 18 kW.
18 kW - 12 kW = 6 KW
6 × 8kW × 0.05 = 2.4 kW
+ 8kw
Total demand load = 10.4 kVA
10.4 kVA × 1000 / 240V = 43 amperes
An apartment building consists of 36 living units. Twenty of the living units are supplied
with 10 kW electric ranges, eight living units are supplied with 12 kW electric ranges and
the remaining eight living units are supplied with 17 kW electric ranges. When figuring the
minimum demand load to be included for the electric ranges for determining the size of
service conductors, it is first necessary to determine the average size of electric range for
the building. For this apartment building, the average electric range size is:
A. 12 kW. C. 13.8 kW. E. 14.4 kW.
B. 13.1 kW. D. 14 kW.
B 13.1 kW
The average range size is determined using the rule in Note 2 of Table 220.19. The trick
is that all ranges smaller than 12 kW (in this case there are 20 at 10 kW) are to be
figured at 12 kW for the purpose of determining the average range size. The method is
as follows:
20 ranges at 10 kW
8 ranges at 12 kW
Take 28 ranges at 12 kW
28 × 12 kW = 336 kW
8 × 17 kW = 136 kW
————–
472 kW ÷ 36 ranges = 13.1 kW
In an apartment building there are 8 living units each with a 3.5 kW, 240 volt electric water
heater. When figuring the demand load for the service to the apartment building, the
minimum demand load that is permitted to be included for the water heaters is:
A. 14 kVA. C. 18.5 kVA. E. 28 kVA.
B. 16.8 kVA. D. 21 kVA.
D 21 kVA
Section 220.53 Appliance Load - permits the application of a demand factor of 0.75 if there are four or more appliances.
Demand load = 8 units × 3.5 kW × 0.75 = 21 kVA
An apartment building is served with single-phase, 120/240 volt, 3-wire power, and has 12
living units each with a 13.5 kW electric range. Using the rules of 220.55, the minimum
load that is required to be included in the service calculation for the electric ranges is:
A. 28.4 kVA. C. 29.7 kVA. E. 162 kVA.
B. 29 kVA. D. 129.6 kVA.
C 29.7 kVA
There are 12 living units and the value for the electric ranges is found in column C of
Table 220.55. Because the ranges are rated greater than 12 kW, the value found incolumn C must be increased by 5 percent for every kW the actual range size is greater than 12. Read Note 2 of Table 220.55. The ranges are 13.5 kW, therefore, this value is
rounded up to 14 before doing the calculation. The following formula can be used to
determine the load that must be included for the ranges.
[(14 - 12) × 0.05 × 27 kVA] + 27 kVA = 29.7 kVA
13.5kva rounded up = 14Kva
- 12kva = 2kva
only above 12 needs derating (.05) 5%
number of appliances (12) = 27kw Column C
2 x 0.05 x 27 + 27 = 29.7 kW
A single-family dwelling is served by a single-phase, 120/240 volt 3-wire service. The
living area of the dwelling is 2400 sq. ft, and the dwelling contains a 12 kW electric range,
a 3.5 kW, 240 volt electric water heater, a ½ horsepower, 120 volt garbage disposer, a 1.2
kVA, 120 volt dishwasher, a 5 kW clothes dryer, a 1½ horsepower, 240 volt central airconditioner,
and a a horsepower, 120 volt furnace blower motor. The minimum load that
is permitted to be included in the calculation to determine the maximum unbalanced load
for the electric range is:
A. zero because the range operates at 240 volts.
B. 5,600 VA
C. 8,000 VA.
D. 8,400 VA.
E. 12,000 VA.
B 5600 VA
For an electric range in a dwelling, a demand factor can be applied according to 220.53.
A 12 kW electric range according to Table 220.55 column C is taken as an 8000 VA load.
In 220.61(B) it is required to take 70% of the range demand load as unbalanced load on the
neutral which in this case is 5600 VA.
8000 VA × 0.7 = 5600 VA
The demand load permitted to be used to determine the minimum rating of branch circuit for a dwelling electric range with a rating of 17.6 kW is:
A. 8 kVA. B. 10.4 kVA. C. 14.1 kVA. D. 17.6 kVA. E. 22 kVA.
10.4kVA
Table 220.19, Note 1 deals with the case where the range is rated greater than 12 kW. The value in column C is increased by 0.05 for each kW the actual range size is greater than 12 kW. It is necessary to round off the nameplate kW to the nearest whole number. In this case round 17.6 up to 18 kW. The first 12 kW is taken at a demand of 8 kVA. Next increase the 8 kVA by 0.05 for each kW larger than 12 as follows:
[(kW [(18 12) × 0.05 × 8kVA] + 8kVA = Range Demand Load 12) × 0.05 × 8kVA] + 8kVA = 2.4kVA + 8kVA = 10.4kVA
MRC — E3602.9 and Table E3604.3(2)
A 120 volt, cord and plug supplied window air-conditioner is permitted to be supplied by a general purpose 20 ampere branch circuit provided the addition of the air-conditioner does not overload the circuit, and provided the full-load current of the air-conditioner does not exceed:
A. 10 amperes. B. 12 amperes. C. 15 amperes. D. 16 amperes. E. 20 amperes.
10 A
When a cord and plug connected window air-conditioner is supplied from a generalpurpose branch circuit, it is not permitted to have a rating in excess of 50% of the rating of the circuit.
This is stated in Section 440.62(C) and Section 210.23(A)(2).
20 A × 0.5 = 10 amperes
