Electrical System 2 Exam Review

A collection of flashcards covering essential terms and concepts from the Electrical System 2 exam to aid study and review.

Demand load

The net electrical load that will probably be used at the same time.

Diversity coefficient

This factor accounts for non-simultaneous loads, such as heating or air-conditioning.

Fixed load

A permanently wired electrical load.

Convenience load

An electrical load with a cord and plug that plugs into a standard receptacle.

Motor branch circuit

A branch circuit that has special provisions to delay tripping a circuit breaker during start-up due to high short-term inrush current.

Dedicated branch circuit

A branch circuit that serves only one item of equipment.

Multi-wire branch circuit

A branch circuit with more than one phase (hot) conductor serving one or more pieces of equipment.

Appliance branch circuit

A branch circuit required for appliances along a kitchen countertop.

Connection diagrams

Electical drawings that provide instructions regarding connections between wiring terminals of devices and equipment.

One-line diagrams

A type of electrical drawing depicting the overall layout of electrical systems.

Riser diagrams

Electrical drawings that depict the layout in a multi-story building.

Star LAN

A topology used in Local Area Network where multiple devices connect to a central hub.

Ring LAN

A topology used in Local Area Network where each device is connected to two others, forming a ring.

Bus LAN

A topology used in Local Area Network where all devices share a single communication line.

Door Position Status Contact

An intrusion detector that activates when the relative positions of a pair of sensors change.

Motion Detector

An intrusion detector that uses infrared sensing to detect body heat.

Photoelectric Detector

An intrusion detection device that activates from a broken light beam.

Intercom

A two-way voice communication system in buildings.

Public Address

A one-way voice communication system in buildings.

Fiber-optic cable

A type of cable that transmits information via tiny light beams through glass filaments.

Twisted-pair cable

A low-voltage communication cable consisting of two 22 or 24-gauge copper wires arranged in a braid pattern.

Coaxial cable

A low-voltage communication cable with two concentric conductors separated by insulating material.

Rate-of-rise heat detector

Identifies an alarm when the temperature at the device increases faster than a preset value.

Water flow switch

Identifies an alarm when a fire sprinkler system has been activated.

Photoelectric smoke detector

Detects an alarm when an infrared LED beam is obscured by combustion byproducts.

Temperature-limit heat detector

Identifies an alarm when the temperature reaches a fixed preset limit.

Conductivity heat detector

Has a sensor that changes resistance with temperature.

Bimetallic heat detector

Uses two strips of different metals with different thermal expansion coefficients.

Cable detector

Uses two copper wires separated by heat-sensitive insulation that melts at a setpoint.

Fusible alloy heat detector

Uses a blend of metals designed to melt rapidly at a specific temperature.

Single Fire Alarm System

A fire alarm system where all horns sound the same pattern at the same time.

Zoned Fire Alarm System

Only horns on a specific floor or area sound an alarm.

Supervised Fire Alarm System

Notifies if a device or wire is cut or shorted.

Coded Fire Alarm System

All horns sound simultaneously but different patterns indicate the fire's location.

Geostationary orbit

Orbit where satellites remain above the same point on Earth.

Equator

The geographic location above which most telecommunication satellites orbit.

22,300 miles

Approximate height above Earth for most telecommunication satellites.

Lay

Length of a single 360-degree twist of twisted-pair cable.

Fire Alarm

Low-voltage systems that should be installed in conduit.

24 Volts AC

Most common operating voltage for telecommunications systems in buildings.

180 Watts

Allowance for each duplex receptacle when items to be plugged in are unknown.

2 feet

Maximum distance from a hypothetical plug-in load to the nearest receptacle in a kitchen.

6 feet

Maximum distance from a hypothetical plug-in load to the nearest receptacle in a living or sleeping room.

Continuous load

Any electrical load that operates for more than 3 hours.

WAN

Can be used instead of a LAN when communication distances are too great.

Analog Output

DDC point example that tells a damper to move to specific positions.

Digital Output

DDC point example that turns a fan on and off.

Analog output

DDC point that receives a temperature message from a thermostat.

Analog signals

Continuous waves which vary in frequency and amplitude.

120/240 1Φ

Most common electrical service in residential construction.

120/208 3Φ

Most common electrical service in midsize commercial construction.

277/480 3Φ

Most common electrical service in large commercial and institutional construction.

Home run

An arrow on conduit drawings pointing to the panelboard.

Panelboard schedule

A table found on electrical drawings listing branch circuits and relevant information.

20 Amps

Ampere rating of the circuit breaker for a general-purpose circuit as per NEC.

12 AWG

Minimum allowable wire gauge for a general-purpose circuit as per NEC.

Oven

An appliance required to be connected to an individual circuit by NEC.

Air conditioner

Another appliance required to be connected to an individual circuit by NEC.

Telephone system

An example of a low-voltage communication system in commercial buildings.

Security camera system

Another example of low-voltage communication systems in commercial buildings.

More efficient HVAC systems

One reason electrical loads have decreased in the last 10 years.

ASHRAE 90.1

Nationally-recognized standard for maximum lighting power density.

CCTV

An example of a low-voltage building operations system.

Transmits faster

An advantage of fiber optic cabling compared to twisted pair cabling.

More expensive

A disadvantage of fiber optic cabling compared to twisted pair cabling.

Cellular floor

Building feature that allows cabling to be routed beneath the floor surface.

Reduces electromagnetic interference

Benefit of twisted-pair cable that reduces noise.