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Electrical Exam 2 Questions And Answers With Verified Solutions Already Passed (Graded A+)
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Electrical Exam 2 Questions And Answers With Verified Solutions Already Passed (Graded A+)
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Electrical Exam 2 Questions AndAnswers With Verified Solutions Already
Passed (Graded A+)
120/240V-1Φ is most likely - ANSWER✔✔Residential & Small Commercial
120/208V-3Φ is most likely - ANSWER✔✔Midsize Commercial
120/208V-3Φ & 277/480V-3Φ probably
Must confirm with Owner that their in-house staff is trained on 480V-3Φ systems -
ANSWER✔✔Large Commercial & Institutional
In general, the following equipment greatly affects the selection of the system type
during the preliminary design period - ANSWER✔✔Elevators
Food service equipment, especially an all-electric kitchen Mechanical equipment
Appliances
Can range from 15-HP to 200-HP, depending on their speed & load capacity
1 HP = 746 Watts
They are usually equipped with three-phase motors - ANSWER✔✔Elevators
>30 kW should be 3Φ
≤30 kW or less can be either 1Φ or 3Φ
In all cases, the equipment voltage must match that of the building system -
ANSWER✔✔Food Service Equipment
Large pieces of mechanical equipment are always designed for 3Φ power Smaller
equipment, such as fans, coils, & unitary equipment, may be available in either 1Φ
or 3Φ power
The selection of HVAC equipment must be a joint decision of the mechanical &
electrical engineers during preliminary design Photo Credit: Burkholder's Heating
& Air Con - ANSWER✔✔Mechanical Equipment
Most household appliances are made for a - ANSWER✔✔120/240V, single phase
system
, If a 120/208V, 3Φ, four-wire system is selected for a very large residence or an
apartment complex: - ANSWER✔✔Must use custom appliances or
Local load-size transformers must be installed at the equipment to boost the system
voltage
Similar for lab & shop equipment
The main electrical power system should be 277/480V-3Φ system for the central
equipment & 120/208V-3Φ for lighting & appliance loads - ANSWER✔✔Large
Apartment Buildings
Once the electrical & mechanical spaces are allocated within the building, -
ANSWER✔✔it is difficult to ask the architect to change its size or location
All equipment & devices must be accessible for - ANSWER✔✔inspection,
service, & replacement
This includes junction boxes
The NEC requires minimum clearances in front of all accessible sides of the
equipment - ANSWER✔✔Switchgear, switchboards, panelboards, load centers,
control panels, disconnect switches, motor starters & VFDs
Up to 150-V - ANSWER✔✔3 ft
151 to 600-V - ANSWER✔✔3-4 ft
601 to 2500-V - ANSWER✔✔3-5 ft
2501 to 9000-V - ANSWER✔✔4-6 ft
is an electrical conduit or other path for wiring to run safely -
ANSWER✔✔raceway
Long dash is the - ANSWER✔✔Neutral
Short dash is a - ANSWER✔✔Hot Conductor
Long dash with dot is - ANSWER✔✔Ground
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