RCDD/TDMM Chapter 9) Power
Distribution Exam 2025 Questions
and Answers
AHJ - ANSWER✔✔-Authority having jurisdiction
Alternate Current (ac) - ANSWER✔✔-A current flow that alternates periodically
(usually sinusoidal) in magnitude and direction
Apparent Power - ANSWER✔✔-The product of the measured voltage and measured
amperage. Expressed in volt amperes
Arc Flash - ANSWER✔✔-A short circuit through the air. When insulation and isolation
between electrified conductors is breached or can no longer withstand the applied
voltage, an arc flash occurs
AWG - ANSWER✔✔-American Wire Gauge; the greater the wire diameter, the smaller
the AWG value
,Capacitance - ANSWER✔✔-1) The ability of an electronic component to store electrical
energy 2) The opposition to a change in voltage
Delta - ANSWER✔✔-The difference between two values, symbolized with a triangle
Direct Current (dc) - ANSWER✔✔-Current flow that has a constant direction. The
letters dc are also used to generically refer to any constant waveform or signal. (EG; a
batter voltage of 3 volts direct current [3Vdc])
Frequency - ANSWER✔✔-The number of cycles that a periodic signal completes in a
given time. If the unit of time is one second, the frequency is stated in hertz (Hz). One
Hz is equal to one cycle per second
Harmonics - ANSWER✔✔-Multiples of the basic frequency of a sine wave (eg the 3rd
harmonic of 60 Hz power frequency is 180 Hz)
Impedance - ANSWER✔✔-The total opposition to ac flow, measured in ohms.
Inductance - ANSWER✔✔-1) The property of an electric force field built around a
conductor when current flows through it. 2) The resistance to change in current
ITE Power - ANSWER✔✔-Information Technology Equipment Power; the power
consumed by ICT to manage, monitor, control, process, store, and route data within a
data center, excluding all infrastructure technology equipment
,LOTO - ANSWER✔✔-Lockout/ Tagout, a means to protect personnel from the
unexpected startup or re-energization of equipment by ensuring that equipment
remains completely off during routing maintenance and repairs.
LVD - ANSWER✔✔-Low voltage disconnect; a device that is used to disconnect the
battery at a preset voltage during battery discharge and allow reconnection only when
utility power has been restored. Called a 'no volt release' in the UK
Noise - ANSWER✔✔-Unwanted electrical signals that were induced onto or
superimposed upon the power line
PDU - ANSWER✔✔-Power distribution unit; a device that has a transformer, surge
suppression, single point ground, panelboards, and monitoring under a single
enclosure
Phase difference - ANSWER✔✔-The relationship in time between two waveforms with
the same frequency
Phase configuration - ANSWER✔✔-The number of phases and the type of connection
between the utility and the user
Power - ANSWER✔✔-1) The rate of transfer or absorption of energy per unit time into a
system 2) The energy required to operate an electrical device (EG: Motor, amplifier,
transmitter)
, Reactance - ANSWER✔✔-The opposition to the flow of ac current caused by
unductance and capacitance. Expressed in ohms.
Redundancy - ANSWER✔✔-Providing secondary components that either become
instantly operational or are continuously operational so that the failure of a primary
component will not result in mission failure
Resistance - ANSWER✔✔-A measure of opposition a material offers to the flow of
direct current. Measured in ohms.
RPP - ANSWER✔✔-Remote Power Panel; a power distribution cabinet downstream
from a PDU or UPS, typically containing circuits or breakers, without a transformer
located near the load.
SDS - ANSWER✔✔-Safety Data Sheet; a document prepared by the manufacturer
describing all known chemical, radiological, and other hazards of a specific product.
Formerly called a material safety data sheet (MSDS)
Short circuit - ANSWER✔✔-A faulty or accidental connection between two points of
different potential in an electrical circuit, bypassing the load and establishing a path of
low resistance through which an excessive current can flow.
Sine Wave - ANSWER✔✔-The mathematical representation of an alternating voltage or
current waveform
Distribution Exam 2025 Questions
and Answers
AHJ - ANSWER✔✔-Authority having jurisdiction
Alternate Current (ac) - ANSWER✔✔-A current flow that alternates periodically
(usually sinusoidal) in magnitude and direction
Apparent Power - ANSWER✔✔-The product of the measured voltage and measured
amperage. Expressed in volt amperes
Arc Flash - ANSWER✔✔-A short circuit through the air. When insulation and isolation
between electrified conductors is breached or can no longer withstand the applied
voltage, an arc flash occurs
AWG - ANSWER✔✔-American Wire Gauge; the greater the wire diameter, the smaller
the AWG value
,Capacitance - ANSWER✔✔-1) The ability of an electronic component to store electrical
energy 2) The opposition to a change in voltage
Delta - ANSWER✔✔-The difference between two values, symbolized with a triangle
Direct Current (dc) - ANSWER✔✔-Current flow that has a constant direction. The
letters dc are also used to generically refer to any constant waveform or signal. (EG; a
batter voltage of 3 volts direct current [3Vdc])
Frequency - ANSWER✔✔-The number of cycles that a periodic signal completes in a
given time. If the unit of time is one second, the frequency is stated in hertz (Hz). One
Hz is equal to one cycle per second
Harmonics - ANSWER✔✔-Multiples of the basic frequency of a sine wave (eg the 3rd
harmonic of 60 Hz power frequency is 180 Hz)
Impedance - ANSWER✔✔-The total opposition to ac flow, measured in ohms.
Inductance - ANSWER✔✔-1) The property of an electric force field built around a
conductor when current flows through it. 2) The resistance to change in current
ITE Power - ANSWER✔✔-Information Technology Equipment Power; the power
consumed by ICT to manage, monitor, control, process, store, and route data within a
data center, excluding all infrastructure technology equipment
,LOTO - ANSWER✔✔-Lockout/ Tagout, a means to protect personnel from the
unexpected startup or re-energization of equipment by ensuring that equipment
remains completely off during routing maintenance and repairs.
LVD - ANSWER✔✔-Low voltage disconnect; a device that is used to disconnect the
battery at a preset voltage during battery discharge and allow reconnection only when
utility power has been restored. Called a 'no volt release' in the UK
Noise - ANSWER✔✔-Unwanted electrical signals that were induced onto or
superimposed upon the power line
PDU - ANSWER✔✔-Power distribution unit; a device that has a transformer, surge
suppression, single point ground, panelboards, and monitoring under a single
enclosure
Phase difference - ANSWER✔✔-The relationship in time between two waveforms with
the same frequency
Phase configuration - ANSWER✔✔-The number of phases and the type of connection
between the utility and the user
Power - ANSWER✔✔-1) The rate of transfer or absorption of energy per unit time into a
system 2) The energy required to operate an electrical device (EG: Motor, amplifier,
transmitter)
, Reactance - ANSWER✔✔-The opposition to the flow of ac current caused by
unductance and capacitance. Expressed in ohms.
Redundancy - ANSWER✔✔-Providing secondary components that either become
instantly operational or are continuously operational so that the failure of a primary
component will not result in mission failure
Resistance - ANSWER✔✔-A measure of opposition a material offers to the flow of
direct current. Measured in ohms.
RPP - ANSWER✔✔-Remote Power Panel; a power distribution cabinet downstream
from a PDU or UPS, typically containing circuits or breakers, without a transformer
located near the load.
SDS - ANSWER✔✔-Safety Data Sheet; a document prepared by the manufacturer
describing all known chemical, radiological, and other hazards of a specific product.
Formerly called a material safety data sheet (MSDS)
Short circuit - ANSWER✔✔-A faulty or accidental connection between two points of
different potential in an electrical circuit, bypassing the load and establishing a path of
low resistance through which an excessive current can flow.
Sine Wave - ANSWER✔✔-The mathematical representation of an alternating voltage or
current waveform
