Dwelling Unit Calculations (NEC Code 240) Practice Test -1
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Free Online Practice Test on Single Family Dwelling Unit calculations – 1
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Question 1 of 10
1. Question
1 pointsA 1600 sq.ft dwelling unit has 16 receptacles and 15 luminaries rated 100 W each, what is the general lighting load of dwelling unit?
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Refer : NEC Table 220.12
1600 * 3 = 4800 Volt-Ampere
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Question 2 of 10
2. Question
1 pointsA quick recovery electric heater is rated 5600 watts 240 volts. What rating of circuit breaker is required for protecting it?
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Refer : NEC 240.6
The ampere rating of heater = 5600/240 = 23.3 amperes
So 25 ampere circuit breaker is required (23.3 is not a standard rating of circuit breaker). -
Question 3 of 10
3. Question
1 pointsThe total connected load of dwelling unit is 11000 VA , what is the calculated demand load?
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Refer : 240.42
First 3000 VA demand factor is = 3000 * 100% = 3000 VA
Remaining (11000 – 3000 ) * 35% = 3150 VA -
Question 4 of 10
4. Question
1 pointsDetermine the feeder demand for a 230 volts dwelling unit consists of Air-conditioning unit FLC (full load current) of 30 amperes and 3 heat circuit of each 3KW ?
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Refer : NEC 220.82 (C)
AC Power Rating = 230 * 30 = 6900 Volt-Ampere
Three Heater Loads = 3 * 3kW = 9000 WThe air condition load is smaller than heater load. So omit the AC load. The bigger load has to be taken.
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Question 5 of 10
5. Question
1 pointsA dwelling unit has four appliances fastened in place with each power rating of 800 VA. what is the demand load appliances?
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If four or more appliances are fastened in place then total demand load = 70% of total rated load
Demand load = 70% * 3200 VA = 2240 VA
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Question 6 of 10
6. Question
1 pointsWhat is the minimum load of household Electric cloth dryer in a dwelling unit?
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Refer: NEC 220.54
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Question 7 of 10
7. Question
1 pointsThe dwelling unit consists of 5 electric cloth dryers, what is the demand load calculated ?
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Refer : NEC 220.54
Total load for 5 electric dryers = 5 * 5000 = 25000 VA
The Demand load = 85 % 25000 = 21250 VA. -
Question 8 of 10
8. Question
1 pointsWhat is calculated demand load for a 15 unit apartment with each apartment has a 900 sq ft area?
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General Lighting load = 900 * 3 VA = 2700 VA
Small Appliance circuits (two minimum) = 3000 VA
Laundry circuit = 1500 VA
total load per apartment = 2700 + 3000 + 1500 = 7200 VA
Total load for 15 apartments = 15 * 7200 VA = 108000 VA
Refer : Table 220.42
First 3000 VA at 100% = 3000 VA
Remaining (108000 – 3000) * 35 % = 36750 VA
Total Demand load = 39750 VA -
Question 9 of 10
9. Question
1 pointsA 8 unit multifamily dwelling unit has an 5 KW electric dryer in each unit. What is total dryer demand load for building service or feeder?
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Refer: NEC 220.54
Total load for 8 units = 8 * 5 = 40 KW
Demand load = 60% * 40 = 24 KW -
Question 10 of 10
10. Question
1 pointsA 3 phase 120/230 Volts Multifamily dwelling building has a total demand load of 220 KVA, What is the minimum size of service conductor that can be used for building?
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Full load current I = P / E * 1.732 = (220 * 1000) / 230 * 1.732 = 552 Amperes
Refer : Table 310.15 (B)(7)
600 kcmil Aluminum Wire per phase