Electrical Theory 5th 1st Final Exam

A branch circuit supplies a continuous load of 68 amperes and a noncontinuous load of 32 amperes. Calculate the minimum standard size inverse-time circuit breaker needed for the branch-circuit overcurrent protection.

125 A

Determine the maximum number of 15-ampere receptacles permitted to be installed on a 120-volt, 20-ampere branch circuit. The circuit supplies only receptable loads in a commercial occupancy.

13

Determine the general lighting load for a two-story office building that measures 125 feet by 150 feet.

131,250 VA

The minimum size of a pull box having an angle pull, with one 2 1/2" conduit entering the box and one 2 1/2" conduit leaving the box is _________. The conductors are larger than 4 AWG and will not be spliced.

15" x 15"

One 10-kilowatt range, one 15-kilowatt range, and one 24-kilowatt range are to be installed in a multifamily dwelling. What is the feeder demand for the three household ranges for the ungrounded conductors only?

17.5 kW

What is the ungrounded conductor feeder demand for four 14-kilowatt household electric ranges installed in a dwelling unit?

18.7 kW

The pressurization factor is an airflow that represents ________ of the supply airflow.

2% - 3%

Nine #10 AWG THWM copper conductors are installed in a run of 1" RMC through an area with an ambient temperature of 45º C. What is the allowable ampacity of each conductor?

20.09 A

A multifamily dwelling has 16 units, with two 120-volt fixed appliances, a 1.3-kilowatt dishwasher, and a 5.5-ampere disposal installed in each unit. What is the feeder demand, in volt-amperes, for the line (and neutral) for the appliances for the apartment complex? Round your answer to the nearest whole number.

23,520 VA

All isolation transformers have an inherent phase shift from primary to secondary of __________ which when used in by-pass configuration would create a potentially disruptive phase conflict when the UPS went to static by-pass.

30 degrees

An office building is 188 feet long and 78 feet wide and has six floors, all office space, with 48 receptacles per floor. The distribution system is 120/208-volt, 3-phase, 4-wire. Calculate the larger of either the receptacle demand in volt-amperes or the lighting feeder demand adder (volt-amperes) due to receptacles.

307,944 VA

What size overcurrent protective device is required to serve a fixed electric space heating load of 28 amperes?

40 A

What is the lighting load for a one-story dwelling unit that is 1,700 square feet in size?

5.1 kVA

Determine the allowable ampacity of three 8 AWG THWN copper conductors installed in EMT, in an ambient temperature of 30º C. All of the conductors are current-carrying conductors.

50 A

A multifamily complex has 30 units with a 120/240 volt, six kilowatt dryer in each unit. What is the dryer load feeder demand for the ungrounded (or line) conductors of this complex? Round your answer to the nearest whole number.

56,700 VA

An apartment complex has a 12-kilowatt range in each of the 44 apartments. What is the feeder demand for the household ranges?

58 kW

The neutral feeder demand for household electric ranges is permitted to be _________ of the feeder demand for the ungrounded conductors.

70%

What is the lighting load for a four-story dwelling unit? The outside dimensions of the building measure 60 feet by 125 feet.

90,000 VA

In addition to temperature ratings of wire terminals, a circuit breaker may be marked with another temperature rating such as 25º C or maybe even as high as 40º C. This marking most likely specifies the _________ temperature.

Ambient

_________ accepts a control signal and causes a mechanical motion.

An actuator

The easiest battery type to service is __________.

Battery cartridge with internal lead acid batteries

_________ switching is a technique to control general light levels by switching individual lamps or groups of lamps in a multi-lamp fixture separately.

Bi-level

An overcurrent protective device prevents _________ from reaching excessively high temperatures, due to high currents, by opening the circuit.

Conductors or devices

________ is the intentional reduction of electrical power to a lamp in order to reduce its light output.

Dimming

The temperature of air that is measured by a thermometer freely exposed to the air but shielded from radiation and moisture is called the _________.

Dry-bulb temperature

Chilled water pumping requires more control than hot water pumping because there must be constant flow through the chiller's ________ or the system will become unstable.

Evaporation coil

A(n) ____________ is an electric lamp that produces light by striking an electrical arc across tungsten electrodes housed inside an arc tube.

High intensity discharge lamp

When utility power is lost or a sever disturbance occurs, the UPS ___________ will shut down.

Input section

What are the two classifications for fuel cells that provide AC power as an output?

Interactive fuel cell system

___________ is the ability of diverse systems and devices to work together effectively and reliably.

Interoperability

In the ________ UPS the inverter is always on and connected to the output of the UPS.

Line interactive

Ground path continuity should be tested for _________ and any ground path utilizing a conduit raceway as the conducting path must have all bolted or screwed connections checked and tested.

Low impedance

Ballasts that are based on inductors are often called __________ ballasts because an inductor is a coil of wire that creates a magnetic field, which resists changes in the current flow through the coil .

Magnetic

_________ are the most common form of automatic lighting control used in buildings .

Occupancy sensor

What was the first type of automated control system used to control the indoor environment in a commercial building?

Pneumatic control system

Large flooded cell battery installation will usually require extensive __________ and may require cell changes which are a specialized function requiring training and certification.

Preventative maintenance

PEM is a type of fuel cell. PEM stands for _________.

Proton exchange membrane

A _________ is an element of the electrical distribution system that at some point will cause downtime if a means to by- pass it is not developed in the system.

SPOF

The __________ feature gradually raises light levels to the desired brightness.

Soft-on

What type of UPS system has high efficiency, small size, and is lower in cost than other types of UPS systems

Stand-by

If the digital inputs for a supply-air fan control application indicate that the supply-air fan should be on, the controller compares the measured __________ to the set point. If this reading is lower than the set point, the supply-air fan speed must be increased.

Static air pressure

If humidity sensors are not used to control humidity, _________ can control humidity by taking advantage of the relationships between temperature and humidity.

Temperature sensors

A ________________ is the end point in an HVAC distribution system, where the conditioned medium (air, water, or steam) is added to or directly influences the environment of the conditioned building space.

Terminal unit

Heating and cooling functions of the HVAC system rely on the basic principles of ___________ and heat transfer.

Thermodynamics

Which ITE tier site(s) is/are fault tolerant?

Tier 4

Instead of having a third terminal used for electronic control signals like most __________, phototransistors use light as the control input.

Transistors

A __________ is a device located at the building zone that provides heating and airflow as needed in order to maintain the desired set points within the building zone

Variable air volume terminal box

__________ are caused by loads near the beginning of a power distribution system, incorrectly wired transformer taps, and large loads being turned off.

Voltage swells

A hydroelectric-generating plant uses __________ to generate electricity.

Water flow

The byproduct(s) of fuel cells is/are __________.

Water, heat and electricity