CITS Electrician (Theory) flashcards
CITS Electrician (Theory) · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Arc flash boundary
- The distance from exposed live parts where incident energy equals 1.2 cal/cm², the level that causes a second-degree burn on unprotected skin.
- Live-dead-live test
- A verification sequence in which the voltage tester is proven on a known live source, applied to the isolated circuit, then proven again to confirm it still functions.
- Lockout/tagout
- A procedure that isolates hazardous energy, applies a personal lock and tag, and verifies absence of voltage before work begins on the equipment.
- Restricted approach boundary
- The distance from exposed live parts that only qualified persons wearing appropriate shock protection may cross, and only with justification for the task.
- Ohm's law
- The relationship V = I × R, stating that voltage across a resistive element equals current through it multiplied by its resistance.
- Three-phase power formula
- For a balanced three-phase load, real power equals the square root of three times line voltage times line current times power factor.
- Power factor
- The ratio of real power in watts to apparent power in volt-amperes; a lagging value indicates inductive loads such as motors.
- Kirchhoff's current law
- The principle that the algebraic sum of currents entering and leaving any node in a circuit equals zero at all times.
- Transformer turns ratio
- The ratio of primary to secondary voltage equals the ratio of primary to secondary turns, and is the inverse of the current ratio.
- Conductor ampacity
- The maximum continuous current a conductor can carry under stated conditions, adjusted for ambient temperature and the number of bundled current-carrying conductors.
- Box fill calculation
- A code method that counts conductors, device yokes, and grounding conductors to confirm the box volume is sufficient for its contents.
- Equipment grounding conductor
- A conductor, colored green or bare, that provides a low-impedance fault path back to the source to facilitate overcurrent device operation.
- NM-B cable
- A nonmetallic-sheathed cable permitted in dry interior locations but prohibited in wet locations, embedded in masonry, or where exposed to physical damage.
- Conduit fill
- A limit on the total cross-sectional area of conductors inside a raceway, expressed as a percentage of the conduit interior area.
- Terminal torque
- The manufacturer-specified tightening value for a lug or terminal; insufficient torque causes overheating and is a leading cause of electrical failure.
- Working clearance
- The minimum depth, width, and height of clear space required in front of electrical equipment, typically 36 inches deep for most panelboards.
- Motor overload protection
- A protective device sized from the motor nameplate current and service factor that protects the motor winding from sustained overcurrent, separate from branch-circuit protection.
- Contactor versus overload relay
- A contactor switches load current on command but provides no overload protection; an overload relay protects the motor but does not switch the load.
- Star-delta starting
- A reduced-voltage starting method that lowers starting current to one-third of direct-on-line values while reducing starting torque by the same proportion.
- Variable frequency drive
- Equipment that controls motor speed by varying supply frequency and voltage, often requiring shielded cable and attention to grounding to limit induced currents.
- Switchgear interrupting rating
- The maximum fault current the equipment can safely interrupt; it must equal or exceed the available fault current at the point of installation.
- Transformer kVA rating
- The apparent power capacity of a transformer, which sets primary and secondary currents according to the respective winding voltages.
- Insulation resistance test
- A DC test voltage applied to insulation to measure resistance; low readings indicate moisture, contamination, or deterioration of the insulation system.
- Clamp meter principle
- The instrument senses the magnetic field around a single conductor; it must encircle only the conductor of interest to give a meaningful current reading.
- Voltage drop under load
- A measurement taken while the circuit carries current, which reveals high-resistance connections that a no-load voltage reading would not show.
- Phase rotation test
- A check of the sequence of three-phase voltages performed before connecting a motor, because reversed rotation can damage the driven equipment.
- Fall-of-potential test
- A method for measuring earth electrode resistance using auxiliary current and potential probes placed at specified distances from the electrode under test.
- NFPA 70E
- The standard for electrical safety in the workplace, covering shock and arc flash risk assessment, approach boundaries, and required personal protective equipment.
- Listed and labeled equipment
- Equipment evaluated by a recognized testing laboratory and installed in accordance with its listing and the manufacturer's instructions; field modification may void the listing.
- Authority having jurisdiction
- The organization or individual responsible for enforcing the code, who may adopt amendments stricter than the model code and who approves installations.
- As-built drawings
- Project documents updated to show the actual installed conditions, including routing changes, added circuits, and revised panel schedules after construction.
- Panel schedule
- A table recording each circuit's number, breaker rating, conductor size, and connected load description, updated whenever circuits are added or changed.