CITS Electrician (Theory) cheat sheet

Lockout/tagout requires isolating the energy source, verifying absence of voltage with a tester rated for the circuit, and applying a personal lock before work begins.

Arc flash boundary is the distance at which incident energy equals 1.2 cal/cm², the threshold for a second-degree burn on bare skin.

Approach boundaries: limited (shock protection only), restricted (qualified persons with PPE), and prohibited (no part of body may cross).

NFPA 70E requires an incident energy analysis or use of the tables; PPE category is selected from the calculated incident energy, not the voltage alone.

Ground-fault circuit protection trips at 4-6 mA for personnel protection; equipment ground-fault protection for equipment operates at higher thresholds (often 30 mA).

A live-dead-live test sequence confirms tester function before and after verifying de-energization; a single test is insufficient evidence.

Minimum approach distance to exposed live parts increases with voltage class; always consult the applicable table rather than estimating.

Working alone on energized equipment above 50 V is prohibited in most jurisdictions; a second qualified person or standby is required.

Ohm's law: V = I × R; power: P = V × I = I²R = V²/R.

Series circuit: current is common; resistances add; voltage divides in proportion to resistance.

Parallel circuit: voltage is common; conductances add; total resistance is always less than the smallest branch resistance.

Three-phase power: P = √3 × V_L × I_L × power factor for a balanced load.

Impedance Z = √(R² + X²); reactance X_L = 2πfL, X_C = 1/(2πfC).

Power factor = real power / apparent power; a lagging power factor indicates inductive load.

Kirchhoff's laws: sum of currents at a node is zero; sum of voltages around a closed loop is zero.

Transformer turns ratio: V₁/V₂ = N₁/N₂ = I₂/I₁; power is essentially conserved (ignoring losses).

Conductor resistance is proportional to length and inversely proportional to cross-sectional area; resistivity rises with temperature for copper and aluminum.

Conductor ampacity depends on insulation temperature rating, ambient temperature, and number of current-carrying conductors bundled together.

NM-B cable is permitted in dry interior locations but not in wet locations, embedded in masonry, or where subject to physical damage.

Rigid metal conduit provides a equipment grounding path and physical protection; EMT requires listed fittings and cannot be used where severe corrosion exists.

Box fill is calculated by counting each conductor, each device yoke, and each equipment grounding conductor per the applicable volume allowance table.

Cable and raceway support intervals and securing distances are specified per wiring method; support must be within a set distance of boxes.

Conductor color coding: grounded conductor white or gray, equipment grounding conductor green or bare, ungrounded conductors other than white, gray, or green.

Aluminum conductors require terminals listed for aluminum; small-gauge aluminum branch conductors are restricted in many applications.

Conduit fill limits keep total conductor cross-sectional area to a percentage of conduit interior area based on the number of conductors.

Terminations must be torqued to the manufacturer's specified value; loose lugs are a leading cause of overheating and failure.

Receptacles in wet or damp locations require listed covers and GFCI protection where specified.

Motor overload protection is sized to the motor's service factor and nameplate current, not the branch-circuit overcurrent device.

Panelboard working clearance requires a minimum depth of 36 inches in front of the equipment, with width and height per the code table.

Bending radius of a raceway must not be less than the minimum specified multiple of the conduit diameter; kinks reduce ampacity and damage insulation.

Periodic thermographic inspection identifies loose connections and unbalanced loading before failure.

Maintenance records should log test results, torque values, and replacement parts to support future troubleshooting and compliance audits.

A transformer's kVA rating is independent of voltage ratio; primary and secondary currents are set by the kVA and the respective voltage.

Motor nameplate data includes voltage, full-load amps, service factor, insulation class, and duty rating; all affect protection sizing.

A contactor switches load current but provides no overload protection; an overload relay provides protection but does not switch the load.

Star-delta starting reduces starting current to one-third of direct-on-line starting but reduces starting torque correspondingly.

VFDs control motor speed by varying frequency and voltage; they can induce shaft currents and require attention to cable shielding and grounding.

UPS systems are rated in VA and kW; the kW rating reflects the real power the inverter can supply at a given power factor.

Switchgear interrupting rating must equal or exceed the available fault current at the point of installation.

Insulation resistance testing applies a DC voltage and measures resistance; readings below the manufacturer's minimum indicate moisture, contamination, or degradation.

Continuity testing must be performed on a de-energized circuit; a live circuit will damage the meter and endanger the tester.

A clamp meter measures current by sensing the magnetic field; it must encircle only the conductor of interest, not both supply and return.

Voltage drop testing under load reveals high-resistance connections that a no-load voltage reading will miss.

Phase rotation meters confirm correct sequence before connecting three-phase motors; reversed rotation can damage driven equipment.

Earth ground resistance is measured with a fall-of-potential or clamp-on method; a single rod often exceeds target resistance and may require multiple rods.

Intermittent faults are best isolated by monitoring and logging while the equipment operates under normal load conditions.

The National Electrical Code (NFPA 70) is the model code adopted with local amendments; the adopted edition governs the installation.

NFPA 70E addresses electrical safety in the workplace, including arc flash and shock risk assessment.

IEEE C2 (National Electrical Safety Code) governs utility supply lines and communications, not customer premises wiring.

Listed and labeled equipment must be installed per its listing and the manufacturer's instructions; field modification may void the listing.

Permits and inspections are required for most new work and alterations; concealed work must be inspected before covering.

Working clearance, box fill, and conductor ampacity tables are code requirements, not recommendations; violations create liability.

Local authorities having jurisdiction may adopt stricter amendments than the model code; always verify the locally enforced edition.

As-built drawings must reflect actual installed conditions, including routing changes, added circuits, and revised panel schedules.

Panel schedules record circuit number, breaker rating, conductor size, and load description; they must be updated whenever circuits change.

A method statement describes the sequence of work, isolation points, and hold points before energization.

Test certificates should record instrument identification, calibration date, ambient conditions, and measured values.

Permit-to-work systems require sign-off at isolation, work completion, and restoration of supply.

Change orders document scope changes, cost impact, and approval before the work proceeds.

Handover documentation includes drawings, test results, equipment manuals, and warranties; incomplete records delay acceptance.