Electrical Flashcards
Which of the following building types would have the most stringent requirements for fire alarm and fire suppression systems? A. motel B. nursing home C. office building D. print shop
B. Nursing home Occupants of institutional buildings, such as hospitals, prisons, and nursing homes, often have limited mobility and require more warning and time to evacuate.
What are transformers used for?
Used to change ac voltages up or down
Information regarding the minimum number of plumbing fixtures required for various occupancies may be found in which of the following sources? A. building codes B. plumbing codes C. both plumbing and building codes D. the local authority having jurisdiction
C. both plumbing and building codes
Interior doors are not to exceed _____ opening force.
5 lbs
- Which one is not a disadvantage of aluminum conductors? a) Cold flow under pressure b) Splicing and terminating difficulties c) Vulnerability to oxidation d) Weight
d) Weight
What is a disadvantage of Cable tray? a) It is free-air rated b) Installation and maintenance is costly c) It is not accessible easily d) It does not work for high wattage
c) It is not accessible easily
Which statement is correct ? a) Conduits can have diameter 1/3 of the slab thickness. b) Conduits running parallel can be spaced as close as .5” far apart. c) Min cover over conduit shall be 3⁄4”
c) Min cover over conduit shall be 3⁄4”
How much cost under floor duct system would add to the building’s electric system cost? 1) 10% 2) 30% 3) 40% 4) 50%
4) 50%
What is the appropriate length of ground Rod ? a) 2’min – 4’ Max b) 4’min – 6’ Max c) 6’min – 8’ Max d) 8’min – 10’ Max
d) 8’min – 10’ Max
What are the max height of switch box and min height of the receptacle above the finished floor? a) 48” max- 15” min b) 44” max- 18” min c) 48” max- 18” min d) 44” max- 15” min
a) 48” max- 15” min
What is the min space requirement around high voltage switchgear? a) 3’-6” b) 5’ c) 6’ d) 8’-6”
c) 6’
When is electric wiring system being inspected by local authorities? I) After raceways been installed II) After the entire job is complete III) After the equipment is installed a) I, II b) I, III c) II, III d) I, II, III
a) I, II
Which one is not the characteristic of Parallel circuits? a) It has one branch connected between the same two points. b) Loads on the current are additive c) The same voltage is imposed on each load. d) It is the standard circuit arrangement in all building wiring.
a) It has one branch connected between the same two points.
What is the predominant use of electrical power in a building? a) Motor b) Lighting c) Heating d) HVAC
b) Lighting
What is the minimum gauge wire allowed in construction? a) 12 b) 14 c) 16 d) 18
b) 14
Name the 3 different plant types a. Electric, hydronic, and forced air b. Boiler/chillers, Refrigeration cycle, Heat pump c. Single pipe, two pipe, three pipe d. Single duct, electric reheat, dual duct
b. Boiler/chillers, Refrigeration cycle, Heat pump
The Hydronic system that may only be extended a very limited distance because each subsequent register gets colder is: a. single pipe b. two pipe c. three pipe d. four pipe
a. single pipe
If both heating and cooling are desired a separate two pipe system can be provided for each, Resulting in a ______ a. Single pipe system b. Two pipe system c. Three pipe system d. Four pipe system
d. Four pipe system
A ______ mixes both the hot and cold in a common return pipe. a. Single pipe system b. Two pipe system c. Three pipe system d. Four pipe system
c. Three pipe system
True or False: electrical systems are the most expensive first costs and the least expensive in life cycle cost.
False
A small Valve in the base of the cooling tower is called a ______ a. Evaporator b. Downdraft c. Condenser d. Blowdown
d. Blowdown
- the Heat Pump ______ a. Creates heat energy b. Moves heat energy c. Harnesses heat energy
b. Moves heat energy
A Prescriptive code: a. State what the final results need to be and how it will be measured, but does not specify how the result is to be achieved. b. States how to build a building.
b. States how to build a building.
Makeup air handling unit is ______ a. An HVAC system that pulls outside air into the serviced room through the mechanical unit. Used with large buildings that would otherwise require extensive ducting. Used when separate utility bills are required. b. Refers to the cooling air, the treatment of the air for temperature and humidity control, air quality and circulation. c. Air handling unit specifically design to apply 100% outside air to the space. This outside air replaces air lost through exhaust fans or the building envelope. d. Air handling unit specifically design to apply 50% outside air to the space. This outside air mixes with internal in the building.
c. Air handling unit specifically design to apply 100% outside air to the space. This outside air replaces air lost through exhaust fans or the building envelope.
What is the requirement for ductwork in a fire rated wall? a. Fire damper b. Fire blanket c. Fire stopping d. Fire Alarm
a. Fire damper
What does a compression tank do for a boiler?
Accommodates the expansion of the water in the system
How is an EMT conduit system joined together?
Set screw and pressure fittings
Why is EMT and IMC conduit more cheaper to install over rigid steel conduit?
Both are lighter and both have larger inside diameters (ID) and therefore easier wire pulling
True or false. Ordinary steel pipe may be used for conduit?
False
When steel conduit is installed in direct contact with earth, how should the conduit be treated?
is is advisable to coat joints with asphaltum. If earth is wet, the entire system should be coated with waterproofing. Alternatively, a plastic jacket conduit can be used
Conduit size depends on what?
maximum permissible temperature of the contained conductors. number and diameter of the wires that may be drawn into the conduit without injuring the wire
True or false. It is preferred to wait for wire installation until conduit inspection has finished
True
What are the advantages of using aluminum conduit?
better corrosion resistance in most atmospheres non magnetic generally doesn’t require painting
What is the main drawback of using aluminum conduit?
it has a deterious effect on many types of concrete when embedded It is also inadvisable to bury aluminum conduit in earth without asphalt or another coating because of corrosion
Where is flexible metal conduit most often used?
used for motor connect and other connections where vibration is present
Where is nonmetallic conduit most often used?
indoor exposed use PVC plastic conduit can be used for outdoor and underground use
What is the main drawback for nonmetallic conduit?
a separate ground wire must be provided because the ground provided by a metallic conduit is absent
The simultaneous production of electricity and heat from a single fuel source is known as what?
Cogeneration
What precautions should be taken if aluminum wiring is used in a building ?
Leads should be cleaned prior to making connections, licensed electricians should be used for installation, larger sizes of copper wire is necessary to carry same amperage
Codes limit the number of conductors permitted in a conduit for what reasons?
Control heat buildup, prevent damage to conductors being pulled through conduit
What is load control?
A technique used to avoid peak demand electrical charges by automatically or manually shutting off nonessential electrical loads before the peak demand is reached
When is multiple metering used?
It is used only for multi tenant spaces
What type of space would you find a ceiling raceway used for electrical distribution?
Spaces that require frequent layout and programmatic changes (merchandising space, educational classrooms)
What is the primary advantage of ceiling raceways?
Even more flexible than underfloor counterparts, energize lighting, provide telephone and power facilities, can supply outlets to floor above
What are the advantages and disadvantages of under carpet wiring systems?
Advantages include simple, low cost installation Disadvantages include interfacing problems with conventional wire
What are full access floors?
Floor constructed of light weight die cast aluminum panels supported on a network of adjustable steel or aluminum pedestals
What criteria does a building need to meet in order to justify the usage of full access floors
Heavy cabling requirement, particularly if frequent recalling and reconnection are required
What are the primary advantages of both cellular metal floor raceway and precast cellular concrete floor raceways?
Large capacity, versatility in that each cell is a potential raceway, and flexibility in outlet placement and movement
Because underfloor duct systems are expensive, what criteria must a building meet in order to justify its usage?
1) floor areas with a requirement for outlets at locations removed from walls and partitions 2) 2) under carpet wiring is inapplicable 3) outlets from ceiling systems are unacceptable 4) frequent rearrangement of furniture and other items requiring electrical and signal service is anticipated
What are the primary disadvantages of underfloor electrical distribution systems?
They are expensive, and become inflexible once the system is cast into concrete
What is an underfloor duct?
An arrangement of parallel rectangular metal or heavy plastic raceways laid on the structural slab and covered with concrete
What are ceiling raceways? And what are the advantages of them in electrical distribution?
Very flexible and most economic as compared to under floor distribution systems
Outlets within 6’ of sink must be protected using what?
Ground Fault Circuit Interrupter
No point is no more than what distance away from an outlet
6 ft
What is the typical distance between outlets?
12 ft
Where are surface metal raceways most typically used? What is the typical voltage contained within this type of conduit?
Only in dry, nonhazardous, noncorrosive locations. Typically contains wiring below 300 V
What are the principle applications of surface metal raceways?
- Where economy in construction weighs very heavily in favor of surface raceways and where expansion is anticipated 2. Where outlets are required at frequent intervals and where rewiring is required and anticipated 3. Where access to equipment in the raceway is required and/or where necessary due to the nature of the wiring 4. Where we wish to avoid the extensive and expensive cutting and patching required to bury a raceway during rewiring
What is a switchgear?
A central electrical distribution center that serves to distribute power to parts of a large building.
Electrical systems in single family homes and duplexes commonly use which type of conductor?
nonmetallic sheathed cable
What is the trade name for nonmetallic sheathed cable? What is it?
Romex. It constists of two or more conductors and a ground wire encased in a plastic jacket. This type of unprotected cable is permitted in wood framed residential buildings and buildings not exceeding three stories as long as it is conealed behind wll and ceilings.
What type of conductors are typically used in commercial construction or in hazardous areas?
Individual conductors placed in rigid metal conduit, such as electric metal tubing (EMT), intermediate metal conduit (IMC), or rigid steel conduit.
What is the trade name for flexible metal clad cable? Where is it typically used>
BX. It consists of two or more conductors inside a continuous inside a continuous spiral wound strip of steel cable. This cable is used where metal shielding is required along with the flexibility to remodel or to connect fixtures that may need to be moved.
What is this switch?
3 pole solid neutral
What is this switch?
single pole single throw
What is this switch?
double pole double throw
What is this switch?
single pole double throw center off
What is this switch?
single pole double throw (3 way switch)
What is this switch?
2 three way switches
Where are wye-delta transformers used?
Commonly used in a step-down transformer, wye connection on the HV side reduces insulation costs, the neutral point on the HV side can be grounded,
Where are delta wye transformers used?
stable with respect to unbalanced loads.
Where are delta delta transformers used?
Commonly used in a step-up transformer for the same reasons as above.
Where are wye-wye transformers used?
Offers the advantage that one of the transform- ers can be removed while the remaining two transformers can deliver three-phase power at 58% of the original bank.
What is this transformer system?
delta delta system
120v/240v
3 phase 4 wires
without the neutral this can be a 240v 3p 3w ora 480v 3p 3w
What transformer system is this?
delta wye
120/208 v 3p 4w
277/480v 3p 4w
what is this?
120/208 v 3p 4w