Residential
Commercial
Conductor/Conduit Sizing
Motor Control
Three Phase Calculations
100

What color insulation is standard for the hot wire in a basic 120V US residential branch circuit?

What is Black?

100

Which type of heavy-duty metal raceway is commonly used in commercial buildings because it can be bent by hand with a tool?

What is EMT?

100
Conductors must be protected against overcurrent by fuses or _______ ________ rated not more than the ampacity of the conductors.
What are circuit breakers?
100

What is the primary purpose of a magnetic contactor in a motor control circuit?

What is to switch a high-current motor load using a low-current control signal. ?

100

Three phase transformers are configured as Delta or ____.

What is Wye?

200

Which size circuit breaker is standard for a residential lighting circuit wired with 14 AWG copper wire?

What is 15A?

200

What is the standard voltage and phase configuration for large commercial buildings to power heavy HVAC and machinery?

What is 277V/480V Three-Phase?

200
The smaller the number, the ______ the conductor and the more current-carrying capacity.
What is larger?
200

Which device protects an electric motor from overheating due to drawing too much current for an extended period?

What is an Overload Relay?

200
In a delta transformer, the Line and Phase voltage are equal, while the Line current is larger then the Phase current by _______.
What is 1.732?
300

How many travelers (swimming wires) run between two switches in a standard 3-way switch configuration?

What is 2?

300

Which type of commercial cable features insulated conductors wrapped in a flexible, interlocking metal armor sheet with an internal green grounding wire?

What is MC (Metal-Clad)?

300
Conduit is either metal or plastic and may be ______?or flexible.
What is rigid?
300

What is the function of a "holding contact" (also known as a sealing or maintaining contact) wired in parallel with a start push button?

What is it keeps the contactor coil energized after the operator releases the momentary start button. ?

300

In a balanced three-phase system, what is the phase angle displacement between any two adjacent voltage waveforms?

What is 120?

400

A standard electric clothes dryer typically runs on a dedicated 240V circuit. What gauge copper wire and breaker size does it normally require?

What is 10 AWG, 30A?

400

In commercial space design, what is the maximum number of current-carrying conductors allowed in a single conduit before you must apply a code-mandated ampacity derating factor?

What is 3?

400
Depends upon three factors: Number of conductors to be installed, Cross-sectional area of the conductors, Permissible raceway fill.
What is conduit sizing?
400

How do you reverse the rotation direction of a standard three-phase AC induction motor?

What is swap any two of the three incoming power phases. 

400

Which popular three-phase transformer connection configuration provides a neutral point, allowing for both line-to-line and line-to-neutral connections?

What is Wye?

500

What happens to the neutral wire when an Arc-Fault Circuit Interrupter (AFCI) detects a parallel arc condition?

What is the breaker opens both the hot and neutral internal path to cut all power. ?

500

Why are isolated ground (IG) receptacles, marked with an orange triangle, used in commercial office or medical spaces?

What is to protect electronic equipment from high-frequency electromagnetic noise on the building ground. ?

500
Four factors affect the current carrying capacity of a conductor. 1. Type material the conductor is made of 2. Diameter of the conductor 3. Length of the conductor 4. ________ of the conductor
What is temperature?
500

In a dual-voltage three-phase motor (e.g., 230V/460V) wired for a Low-Voltage (230V) application, how must the internal phase windings be connected?

What is in Parallel.

500
True or False, three phase transformers and loads can be configured in delta-delta, delta-wye, wye-wye and wye delta configurations?
What is True?