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COSC 325 MEP Electrical & Mechanical FINAL ACTUAL
EXAM 2025 COMPLETE 100 QUESTIONS AND CORRECT
DETAILED ANSWERS WITH RATIONALES|ALREADY
GRADED A+
Conductor/wire: Copper v. Aluminum - CORRECT ANSWER >>> Copper is a better conductor, but is more expensive. Aluminum needs to be bigger to carry as much as copper. Generated Electricity - CORRECT ANSWER >>> The Alternating Current (AC) created by power plant generators. How many "hot" wires does a 3-phase have? How many neutrals? How many grounds? - CORRECT ANSWER >>> 3, 1, 1 How many "hot" wires does a Single phase have? - CORRECT ANSWER >>> 2 What color is a "hot" wire usually? - CORRECT ANSWER >>> Black/Red What does a Transformer do? - CORRECT ANSWER >>> Uses electromagnetism to step down the voltage to a lower voltage that the building can use and steps up amps. If amps drive wire size, then is Primary or Secondary bigger? - CORRECT ANSWER >>> Secondary What does a System Ground do? - CORRECT ANSWER >>> Protects the service entrance wiring and connections from lightning and high voltage surges.
What is a Fuse? - CORRECT ANSWER >>> an electric overcurrent protection device used to limit the rate of current flow in a circuit. What is a Circuit Breaker? - CORRECT ANSWER >>> An overcurrent protection device with a mechanical mechanism that may manually or automatically open a circuit when an overload condition or short circuit occurs. What is the most common type of Circuit Breaker? - CORRECT ANSWER >>> ThermalMagnetic Circuit Breaker What is the maximum height at which a circuit breaker handle can be installed? - CORRECT ANSWER >>> 6' - 7" What is the most popular overcurrent device? - CORRECT ANSWER >>> Fuses What is a GFCI? - CORRECT ANSWER >>> A fast-acting receptacle that detects low levels of leakage current to ground and opens the circuit in response to the leakage. Where is a GFCI typically installed? - CORRECT ANSWER >>> Indoors: Standard receptacle boxes Outdoor: Weatherproof boxes What is the smallest current leakage a GFCI can detect? - CORRECT ANSWER >>> .005A Purpose of LOTO - CORRECT ANSWER >>> Stop the electrical flow upstream of the electrical current.
What is the function of a Receptacle? - CORRECT ANSWER >>> To supply current to portable electrical equipment. What is Ground Fault? - CORRECT ANSWER >>> Any current above the level that is required for a dangerous shock. What is the most common way to install NM cable (Romex)? - CORRECT ANSWER >>> By running it through a stud wall and floor joists through drilled holes. How many conductors does NM cable usually contain? - CORRECT ANSWER >>> 2 - 3 insulated conductors and a separate bare ground wire. Where must Receptacle boxes/Junction boxes be installed? - CORRECT ANSWER >>> At every point in the electrical system where NM cable is spliced or terminated. What is the purpose of Receptacle boxes/Junction boxes? - CORRECT ANSWER >>> So that every point in the electrical system is accessible for future repairs or additions. What type of conduit is a heavy duty pipe that is threaded on the ends much like standard plumbing pipe? - CORRECT ANSWER >>> Rigid Metal Conduit (RMC) What type of conduit is a light-gauge electrical pipe that is often referred to as thin-wall conduit.
- CORRECT ANSWER >>> Electrical Metallic Tubing (EMT) What type of conduit has no wires and can be bent by hand, and is used where some type of movement or vibration is present? - CORRECT ANSWER >>> Flexible Metal Conduit (FMC) When are the conductors installed in FMC? - CORRECT ANSWER >>> Not until after the system is complete.
What is a Generator? - CORRECT ANSWER >>> An electromechanical device that converts mechanical energy into electrical energy by means of electromagnetic induction. What does an Automatic Transfer Switch (ATS) do? - CORRECT ANSWER >>> Automatically transfers the load of a residence from public utility circuits to the output of a standby generator when it senses an interruption in power during a power failure. What is the Input side of a transformer? - CORRECT ANSWER >>> Primary What does Lumens measure? - CORRECT ANSWER >>> The total amount of light produced by a light source. What does Footcandles measure? - CORRECT ANSWER >>> The amount of light produced by a lamp (lumens) divided by the area. What is an Incandescent light? - CORRECT ANSWER >>> An electric lamp that produces light by the flow of current through a tungsten filament inside a sealed glass bulb sometimes filled with gas. What is a Fluorescent light? - CORRECT ANSWER >>> A low-pressure discharge lamp in which ionization of mercury vapor transforms ultraviolet energy generated by the discharge into light. What is a Compact Fluorescent light? - CORRECT ANSWER >>> A fluorescent lamp that has a smaller diameter than a conventional fluorescent lamp and a folded bulb configuration. What is the NEC requirement for clearance in front of a panel? - CORRECT ANSWER >>> 3ft
What is the standard time that generators start time has to be under to support life safety systems? - CORRECT ANSWER >>> 10 seconds What is power formula for a single phase circuit? - CORRECT ANSWER >>> P = V x A What is the power formula for a three phase circuit? - CORRECT ANSWER >>> P = V x A x 1. What is a problem within an electrical system? - CORRECT ANSWER >>> Fault What can Branch circuits not be made of? - CORRECT ANSWER >>> Aluminum What are the wires that feed panels called? - CORRECT ANSWER >>> Feeders What is the most common kind of fuel for Generators? - CORRECT ANSWER >>> Diesel What is the unit of measure for one unit of this to equal the amount of heat required to raise 1lb. of water 1'F? - CORRECT ANSWER >>> Btu What is the unit of measure for one unit of this to equal the amount of heat required to melt a ton of ice (2000lbs.)? - CORRECT ANSWER >>> Ton How many Btu's are in 1 ton? - CORRECT ANSWER >>> 12,000 Btu About how many square feet does 1 ton of cooling cover? - CORRECT ANSWER >>> ~350 sf. What does Humidity refer to? - CORRECT ANSWER >>> The amount of moisture in the air.
What is Relative Humidity? - CORRECT ANSWER >>> The amount of moisture in the air compared to the amount of moisture the air would hold at the same temperature if it were saturated. What percentage of Relative Humidity is considered Comfortable Relative Humidity? - CORRECT ANSWER >>> 50% What is Air Velocity? - CORRECT ANSWER >>> The speed at which air moves from one point to another. What is Flow Rate measured in? - CORRECT ANSWER >>> Feet per minute (fpm) What kind of ductwork is used to distribute air to different building spaces? **- CORRECT ANSWER
** Supply Air Ductwork and Registers What type of ducts need to be insulated? - CORRECT ANSWER >>> Sheet Metal How is Supply Air Ductwork sized and located? - CORRECT ANSWER >>> Sized and located for
** Diesel What is the unit of measure for one unit of this to equal the amount of heat required to raise 1lb. of water 1'F? - CORRECT ANSWER >>> Btu What is the unit of measure for one unit of this to equal the amount of heat required to melt a ton of ice (2000lbs.)? - CORRECT ANSWER >>> Ton How many Btu's are in 1 ton? - CORRECT ANSWER >>> 12,000 Btu About how many square feet does 1 ton of cooling cover? - CORRECT ANSWER >>> ~350 sf. What does Humidity refer to? - CORRECT ANSWER >>> The amount of moisture in the air. What is Relative Humidity? - CORRECT ANSWER >>> The amount of moisture in the air compared to the amount of moisture the air would hold at the same temperature if it were saturated. What percentage of Relative Humidity is considered Comfortable Relative Humidity? - CORRECT ANSWER >>> 50% What is Air Velocity? - CORRECT ANSWER >>> The speed at which air moves from one point to another. What is Flow Rate measured in? - CORRECT ANSWER >>> Feet per minute (fpm) What kind of ductwork is used to distribute air to different building spaces? - CORRECT ANSWER >>> Supply Air Ductwork and Registers What type of ducts need to be insulated? - CORRECT ANSWER >>> Sheet Metal How is Supply Air Ductwork sized and located? - CORRECT ANSWER >>> Sized and located for maximum efficiency. What are used to move air from building spaces back to the blower? **- CORRECT ANSWER ** Return Air Ductwork and Grilles What is Filtration? - CORRECT ANSWER >>> The process of removing particles and contaminants from air that circulates through an air distribution system. What are the locations of filters in air systems? - CORRECT ANSWER >>> In the air ductwork where air enters the heating or cooling equipment.
What are the major parts of a forced-air heating system? - CORRECT ANSWER >>> The heating unit, distribution system, and controls. What is a self-contained heating unit that includes a blower, burner(s) and heat exchanger or electric heating elements, and controls? - CORRECT ANSWER >>> Furnace How are Furnaces categorized? - CORRECT ANSWER >>> The direction of airflow out of the furnace. What type of blower/fan consists of blades mounted on a central hub? **- CORRECT ANSWER
** Propeller fan Where are Propeller fans usually used? - CORRECT ANSWER >>> Where there is no ductwork. What type of blower/fan consists of a scroll, blower wheel, shaft, and inlet vanes? - CORRECT ANSWER >>> Centrifugal blower What type of blower/fan contains a blower wheel, which works like a turbine wheel? - CORRECT ANSWER >>> Axial flow blower What is Static Pressure? - CORRECT ANSWER >>> The pressure that acts through weight only with no motion. What are devices that transfer heat from one substance to another without allowing the
substances to mix? - CORRECT ANSWER >>> Heat Exchangers What is a Clamshell Heat Exchanger? - CORRECT ANSWER >>> A device that has multiple clam- shaped sections that are made out of medium-gauge sheet metal or cast iron.
What is a Drum Heat Exchanger? - CORRECT ANSWER >>> A round drum or tube that is located on a combustion chamber to make the products of combustion flow through it. What kind of filters contain filter media made of fiberglass or other fibrous material and whose fibers are treated with oil to help them hold dust and dirt? **- CORRECT ANSWER
** Lowefficiency filters (40%) What kind of filters contain filter media made of dense fibrous mats or filter paper and are used in applications such as office buildings? - CORRECT ANSWER >>> Medium-efficiency filters (40%- 80%) What kind of filters contain filter media made of large bags of filter paper? **- CORRECT ANSWER ** High-efficiency filters (80%-90%) What filter efficiency do hospitals or laboratories need? - CORRECT ANSWER >>> Highefficiency What type of ductwork system makes it possible to keep ductwork close to building support members? - CORRECT ANSWER >>> Trunk & Branch Ducts What extends from the trunk to each register? - CORRECT ANSWER >>> Branches What kind of ductwork makes installations and retrofits much easier, especially when space is a premium? - CORRECT ANSWER >>> Flexible ductwork What is a disadvantage of Flexible ductwork? - CORRECT ANSWER >>> Air pressure is lower than Rigid ductwork. Besides easier installation, what is another advantage of Flexible ductwork? - CORRECT ANSWER >>> Absorbs vibrations and pulsations that might cause noise.
What is the steam supply system? - CORRECT ANSWER >>> The piping and support systems that provide a path for steam flow from the boiler to the point of use. What is the condensate return system? - CORRECT ANSWER >>> The system used to return condensate back to the boiler after all the useful heat has been removed. What heating system component transfers heat from hot water in a hydronic heating system to the air in building spaces? - CORRECT ANSWER >>> Terminal devices Direct Drive and Belt Drive are types of what? - CORRECT ANSWER >>> Pump drives What is the device that is a stand-alone thermostat that can be programmed by the building occupants? - CORRECT ANSWER >>> Programmable thermostat What is the process of moving heat from an area where it is undesirable to an area where the heat is no objectionable? - CORRECT ANSWER >>> Refrigeration What is a Refrigeration system? - CORRECT ANSWER >>> A closed system that controls the pressure and temperature of a refrigerant to regulate the absorption and rejection of heat by the refrigerant. What is the mechanical device that compresses refrigerant or other fluid? **- CORRECT ANSWER
** Compressor What does a compressor do? - CORRECT ANSWER >>> Increases the temperature of and pressure on refrigerant vapor and produces high pressure side of the system. TXV and EXV are examples of what? - CORRECT ANSWER >>> Expansion devices
What is an Expansion device? - CORRECT ANSWER >>> A valve or mechanical device that reduces the pressure on a liquid refrigerant by allowing the refrigerant to expand. What is an Evaporator? - CORRECT ANSWER >>> A heat exchanger that adds heat to lowpressure refrigerant liquid. Suction line vs. Liquid line - CORRECT ANSWER >>> Suction line: carries cool gas, Insulated and larger than liquid line. Liquid line: carries warm liquid, Smaller and uninsulated. Is the Condenser on the High-pressure or Low-pressure side of a refrigeration system? - CORRECT ANSWER >>> High-pressure side How does the temperature change when the water that is circulating through a hydronic air conditioning system and is sent into the chiller? - CORRECT ANSWER >>> 45' to 55' What is an Evaporative heat exchanger that removes heat from water? **- CORRECT ANSWER
** Cooling Tower What is an air conditioning system that has separate cabinets for the evaporator and the condenser? - CORRECT ANSWER >>> Split system What is a self-contained air conditioner that has all the components in one sheet metal cabinet?
- CORRECT ANSWER >>> Packaged unit What is an RTU? - CORRECT ANSWER >>> An air-cooled packaged unit that is located on the roof of a building.
What is the most common material used for rigid ductwork? **- CORRECT ANSWER
** Galvanized Steel What shape of ductwork is the cheapest? Most expensive? - CORRECT ANSWER >>> Rectangular, Oval What are materials commonly found in residential ductwork? - CORRECT ANSWER >>> Flex duct, Fiberglass Duct Board, Pookie What duct material does not have to be insulated? - CORRECT ANSWER >>> Ductboard EER - CORRECT ANSWER >>> Energy Efficiency Ratio SEER - CORRECT ANSWER >>> Seasonal Energy Efficiency Ratio IEER - CORRECT ANSWER >>> Integrated Energy Efficiency Ratio What is the minimum R value for outside ducts? - CORRECT ANSWER >>> R Why do RTU's need to be elevated? - CORRECT ANSWER >>> To allow condensate to drain. What is the order of Taps from best to worst? - CORRECT ANSWER >>> Angle tap, Conical tap, and Straight tap. VRF - CORRECT ANSWER >>> Variable Refrigerant Flow
VRV - CORRECT ANSWER >>> Variable Refrigerant Volume DOAS - CORRECT ANSWER >>> Dedicated Outdoor Air System GSHP - CORRECT ANSWER >>> Ground Source Heat Pump What type of Exhaust Fan system pumps large amounts of air out of the building? - CORRECT ANSWER >>> Laboratory Exhaust fan What are the advantages of using Cast Iron for sewer pipes? - CORRECT ANSWER >>> Flame resistant, lasts a long time, and dampens sound. What is a disadvantage of using Cast Iron for sewer pipes? - CORRECT ANSWER >>> Very labor intensive to install. How much heat per hour does the average person give off? - CORRECT ANSWER >>> 250 Btu/h What are VFD's commonly used in? - CORRECT ANSWER >>> Large fan motors What usually controls a Duct heater? - CORRECT ANSWER >>> A central control system What are the 2 joining methods for Cast Iron pipes? - CORRECT ANSWER >>> Hub and Pipe Clamps What are the 3 ways to join Copper pipes? - CORRECT ANSWER >>> Solder connection, Threaded connection, and Compress fitting
