CSLB C-10 Electrical Contractor flashcards

An 'Over Limit' or 'Open Loop' indication on a multimeter, usually in continuity or resistance mode, signifying infinite resistance or a break in the circuit.

• Indicates open circuit
• No complete path for current
• Common in continuity/resistance modes

Memory trick: OL means Open Line!

A critical safety check to ensure test leads are inserted into the correct jacks (e.g., voltage, current, common) on a Digital Multimeter before connecting to a circuit.

• Prevents short circuits
• Avoids DMM damage
• Protects the user from arc flash/shock

Memory trick: Jacks First, Then Function, Then Range!

An electrical test instrument used to measure very high electrical resistances, typically in megohms, by applying a high DC voltage. It is primarily used to test the integrity of insulation in electrical systems.

• Applies high DC voltage (e.g., 500V, 1000V).
• Measures insulation resistance to detect faults.
• Essential for preventative maintenance and troubleshooting of high-voltage equipment.

Memory trick: Insulation needs Megger, Continuity needs Buzzer, Phases need a Spinner.

An electrical test instrument used to determine the correct phase sequence (rotation) of a three-phase power supply. This is critical for ensuring proper operation and preventing damage to three-phase motors and other rotational equipment.

• Identifies clockwise or counter-clockwise phase sequence.
• Essential for 3-phase motor installations.
• Prevents reverse rotation and potential damage.

Memory trick: For Rotation, Use the Rotation Nation!

A test performed on a de-energized circuit to confirm an unbroken electrical path, typically using a multimeter's resistance function.

• Performed on de-energized circuits only.
• Measures resistance (ohms).
• Used to check for open circuits or short circuits.

Memory trick: Volt, Amp, Ohm: Know your DMM's role!

Specific items of personal protective equipment mandated by NFPA 70E for different Arc Flash PPE Categories to protect workers from arc flash hazards.

• Requirements vary by category
• Includes clothing, head protection, hand protection
• All items must be arc-rated

Memory trick: Cat 4: Full Suit, Face Shield, Balaclava!

To verify proper grounding of a 120V receptacle, a multimeter measurement between the hot (small slot) and the equipment grounding conductor (round hole) should yield approximately 120 volts.

• Hot to ground should read nominal circuit voltage.
• Hot to neutral should read nominal circuit voltage.
• Neutral to ground should read near 0 volts.
• Tests for proper wiring and safety.

Memory trick: Hot to Ground, 120 is Found!

An electrical test instrument that measures current flowing through a conductor by detecting the magnetic field around it, without requiring direct electrical contact or breaking the circuit.

• Measures AC and/or DC current.
• Non-contact measurement, enhancing safety.
• Ideal for troubleshooting live circuits without interruption.

Memory trick: V-O-C-M: Voltage, Ohms, Current, Megohms – Each has its own tool.

Temporary grounding conductors applied to de-energized electrical equipment to protect workers from electric shock hazards.

• Applied after lockout/tagout and absence of voltage verification.
• Protects against accidental re-energization.
• Protects against induced voltages and stored energy.

Memory trick: Grounds: Your Safety Net Against Surprises.

The final confirmation using a test instrument that an electrical circuit or equipment is de-energized after lockout/tagout procedures have been applied.

• Must use a properly rated and tested voltage detector.
• Check all phases, conductors, and ground points.
• Performed immediately before beginning work on the equipment.

Memory trick: Always Start The Process, Isolate, Lock, Test, Then Work Safely.

An electrical instrument used to measure electrical resistance in ohms (Ω).

• Measures resistance
• Requires circuit to be de-energized
• Used for troubleshooting shorts, opens, and winding integrity

Memory trick: AVO: Always Verify Ohms!

The essential safety practice of testing a voltage detector on a known live source immediately before and after testing a circuit for absence of voltage, ensuring the detector is functioning correctly.

• Performed 'prove-before-prove-after' sequence.
• Ensures accurate reading for safety.
• A low battery or malfunction requires re-testing with a reliable device.

Memory trick: Test, Then Test, Then Test Again, Be Sure!

The precise placement of current and potential probes in a ground resistance test to ensure accurate measurement of the grounding electrode's resistance to earth.

• Critical for accuracy
• Avoids overlapping resistance fields
• Potential probe typically at 62% distance

Memory trick: Fall-of-Potential: Space Probes Right!

Requirement by Cal/OSHA to protect against accidental contact with energized electrical components operating at 50 volts or more.

• Applies to 50V and above
• Prevents accidental contact
• Achieved by enclosures, barriers, isolation, or elevation

Memory trick: Guard 50V and UP!

The main result of an arc flash risk assessment is the determination of the Arc Flash Boundary and the incident energy level, which guides the selection of appropriate arc-rated personal protective equipment (PPE).

• Identifies arc flash hazards.
• Determines incident energy and arc flash boundary.
• Specifies arc-rated PPE requirements.
• Required by NFPA 70E for safe work practices.

Memory trick: Assess the Flash, Find the Boundary, Get the Gear.

An imaginary boundary around energized electrical equipment, defined by NFPA 70E, where the incident energy of an arc flash is 1.2 cal/cm² (the onset of a second-degree burn).

• Requires arc-rated PPE for entry.
• Protects against thermal effects of an arc flash.
• Determined through an arc flash risk assessment.

Memory trick: Approach Carefully, Restricted Zone, Flash Hazard Ahead!

Cal/OSHA mandates that non-current-carrying metal parts of electrical equipment, raceways, and enclosures operating at 50 volts or more to ground must be bonded together and connected to an effective ground-fault current path.

• Applies to equipment operating at 50V or more.
• Protects against electric shock by clearing ground faults.
• Requires both bonding (connecting metal parts) and grounding (connecting to earth).

Memory trick: OSHA's Golden Rule: Ground Everything Over Fifty!

Evaluating megohmmeter readings to determine the health and integrity of electrical insulation, typically using industry rules of thumb or specific standards.

• Higher resistance is better
• Readings depend on voltage and equipment type
• Trends over time are important

Memory trick: Resistance Rule: 1 Megohm per 1000V + 1 MΩ is a good start!

To test a GFCI receptacle, press the 'TEST' button, which simulates a ground fault and should cause the GFCI to trip. Then, press the 'RESET' button to restore power, confirming its proper operation.

• Built-in 'TEST' button simulates a ground fault.
• Tripping indicates proper function.
• Should be tested monthly and after installation/maintenance.
• Always follow with a 'RESET' to restore power.

Memory trick: Test, Trip, Reset: The GFCI Safety Dance!

A systematic approach to controlling hazards, prioritizing elimination, substitution, engineering controls, administrative controls, and finally, personal protective equipment (PPE) as the least effective but often necessary last resort.

• Elimination/Substitution are most effective.
• Engineering controls modify the work environment.
• Administrative controls modify work practices.
• PPE is the last line of defense, protecting the worker from the hazard.

Memory trick: Eliminate, Substitute, Engineer, Administer, Protect!

Requirement for clear and durable identification on electrical equipment to provide essential safety information to workers.

• Crucial for safety
• Identifies equipment, hazards, voltage
• Facilitates LOTO procedures

Memory trick: Labels Mean Safety First!

A classification system by NFPA 70E that specifies the minimum arc rating of PPE required based on calculated incident energy levels.

• Higher category = higher arc rating
• Determined by incident energy calculations
• Ensures worker protection from arc flash

Memory trick: PPE Categories: 1.2, 4, 8, 25!

The step in establishing an electrically safe work condition that involves using a test instrument to confirm no voltage is present after de-energization and lockout/tagout.

• Follows LOTO application
• Precedes protective grounding
• Essential for worker safety

Memory trick: SAFE: Stop, Apply, Verify, Establish!

Before connecting a Digital Multimeter (DMM) to a live circuit, always ensure it is set to the correct measurement function (e.g., AC Volts) and an appropriate range (if not auto-ranging) to prevent meter damage and ensure user safety.

• Incorrect settings can cause meter damage or electrical hazards.
• Always select a range higher than the expected voltage initially.
• Check lead connections to the correct input jacks.
• Part of a comprehensive 'prove-before-prove-after' testing sequence.

Memory trick: Function First, Range Right, Leads Last, Live Later!

The National Electrical Code (NEC) permits a maximum of six service disconnects, grouped in a single location, to disconnect all ungrounded conductors from the service-entrance conductors.

• Applies to service disconnects, not branch circuit breakers.
• Disconnects must be grouped in one readily accessible location.
• Each disconnect must clearly indicate the load it controls.

Memory trick: Six Disconnects: 'S'afety 'S'tarts 'S'imply 'S'ix 'S'witches 'S'ecure.

When more than three current-carrying conductors are installed in a raceway or cable, the ampacity of each conductor must be reduced by an adjustment factor from NEC Table 310.15(C)(1).

• Only current-carrying conductors are counted.
• Neutral conductors in a balanced 3-phase, 4-wire system are generally not counted.
• Equipment grounding conductors are never counted.

Memory trick: Count Conductors: 'L'ive 'P'hases 'O'nly (unless neutral is unbalanced).

Conductors supplying a single motor used in continuous duty must have an ampacity of at least 125% of the motor's full-load current.

• Applies to continuous-duty motors.
• Minimum ampacity = FLC x 1.25.
• Conductor ampacity must be chosen from appropriate temperature column (e.g., 75°C for THWN-2).

Memory trick: Motor Conductors Need Extra Juice: Multiply FLC by 1.25.

All 120-volt, 15- and 20-ampere receptacles in commercial kitchens are required to have ground-fault circuit interrupter (GFCI) protection, regardless of their location or proximity to water sources.

• Applies to 15A and 20A, 120V receptacles.
• Mandatory in commercial kitchens.
• No distance exemption for sinks (unlike other non-dwelling locations).

Memory trick: GFCI for Non-Dwellings: Wet, Work, Wash, Water.

The minimum clear space required in front of electrical equipment, determined by voltage to ground and the type of obstruction opposite the equipment, to allow for safe operation and maintenance.

• Determined by voltage to ground and conditions (1, 2, or 3).
• Condition 1: Exposed live parts on one side, grounded surface on the other.
• Condition 2: Exposed live parts on one side, no live or grounded parts on the other, or live parts on both sides that are effectively guarded.
• Condition 3: Exposed live parts on both sides of the working space.

Memory trick: Working Space: 'V'oltage and 'C'ondition are Key.

In an AC circuit, resistance (R) can be determined from the total impedance (Z) and the power factor (PF) using the relationship R = Z × PF. This comes from the power triangle where PF = cos(θ) = R/Z.

• PF = R/Z for an AC circuit.
• Resistance (R) is the real part of impedance.
• Measured in Ohms (Ω).

Memory trick: Power Factor is R over Z, so Resistance is Z times Power Factor.

Capacitive reactance (Xc) is the opposition a capacitor offers to the flow of alternating current (AC). It is inversely proportional to both the capacitance and the frequency.

• Formula: Xc = 1 / (2πfC)
• Measured in Ohms (Ω).
• Causes current to lead voltage by 90 degrees in a purely capacitive circuit.

Memory trick: Capacitors Resist Current, but Reactance is 1 over 2 Pi FC.

The turns ratio for a three-phase transformer relates the primary and secondary line-to-line voltages to the number of turns in each winding, similar to single-phase transformers.

• Vp/Vs = Np/Ns (Vp = primary line voltage, Vs = secondary line voltage).
• For Wye secondary, line-to-line voltage is √3 times line-to-neutral voltage.
• Ensures accurate voltage transformation for balanced three-phase loads.

Memory trick: Voltage Ratio is Turns Ratio, but remember Line-to-Line for 3-Phase.

The ground resistance reading obtained from a Fall-of-Potential test is directly displayed by the test instrument when the potential electrode is positioned correctly.

• Meter directly measures resistance.
• Electrode spacing is critical for accuracy.
• No calculation required from the meter's reading itself.

Memory trick: The meter's number is the answer, no tricks!

On a digital multimeter, 'OL' (Over Limit or Open Loop) during a resistance measurement indicates that the resistance being measured is infinite or exceeds the meter's maximum range.

• Typically signifies an open circuit.
• Meter cannot complete the circuit to measure resistance.
• Common when testing broken wires or components.

Memory trick: OL means Open Line, no path for current.

In a purely resistive AC circuit, impedance (Z) is equal to the resistance (R) because there are no reactive components (inductors or capacitors) to cause phase shifts. It represents the total opposition to current flow.

• For purely resistive circuits, Z = R.
• Calculated using Ohm's Law: Z = V/I.
• Measured in Ohms (Ω).

Memory trick: Resistive means Impedance is just Resistance, simple Ohm's Law.

Before measuring live voltage with a DMM, ensure test leads are visually inspected for damage and properly connected to prevent electric shock or equipment damage.

• Inspect leads for cracks, frayed insulation.
• Confirm tight connection to DMM and probes.
• Prevents exposure to live voltage.

Memory trick: Leads are your lifeline, check them first!

Reactive power in a single-phase AC circuit is the power that oscillates between the source and the reactive components (inductors and capacitors), not doing any useful work. It is measured in volt-amperes reactive (VAR).

• Formula: Q = V × I × sin(θ).
• θ is the phase angle, where PF = cos(θ).
• Measured in VAR or kVAR.

Memory trick: Reactive is V I Sine Theta, when Cosine Theta is Power Factor.

A safety procedure used to ensure that dangerous machines are properly shut off and not able to be started up again prior to the completion of maintenance or servicing work. It involves isolating energy sources and physically locking them in an 'off' or 'safe' position.

• Mandatory for control of hazardous energy according to Cal/OSHA and NFPA 70E.
• Involves physical lockout devices and personal tags.
• Prevents accidental re-energization during maintenance or service.

Memory trick: Lock Out, Tag Out, Stay Safe, No Doubt!

The method of determining the current in a 3-phase electrical circuit, typically used for sizing conductors and overcurrent protective devices based on the total apparent power (VA or kVA) and line-to-line voltage.

• Uses the formula I = VA / (√3 * V).
• √3 (square root of 3) is approximately 1.732.
• Crucial for proper sizing of electrical components in 3-phase systems.

Memory trick: Three-phase amps: 'KVA' and 'VOLTS' with a 'ROOT-3' twist.

Standardized graphical representations used on electrical blueprints to denote the type and location of switches, crucial for planning and installation.

• Symbols are defined by industry standards (e.g., ANSI, IEEE, or local conventions).
• A single-pole switch (S) typically has a specific symbol to distinguish it from other switch types.
• Understanding these symbols is essential for accurate material takeoffs and installation.

Memory trick: Switches Start Simple, Get Complex

The suitability of conduit for outdoor exposure depends on its material, construction, and listing, particularly concerning resistance to corrosion, UV degradation, and physical damage.

• RMC/IMC are generally robust for outdoor use
• PVC needs to be sunlight-resistant for exposed outdoor runs
• EMT is less suitable for exposed outdoor conditions without additional protection

Memory trick: Outdoor conduits need to Resist the elements, not just route wires.

Wiring methods in hazardous locations must prevent ignition of flammable gases, vapors, liquids, combustible dust, or ignitable fibers, requiring specialized conduit, cable, and sealing techniques.

• Hazardous locations are classified by type (Class I, II, III) and degree of hazard (Division 1, 2).
• Wiring methods like RMC, IMC, and certain MC cables are often permitted.
• EMT and flexible conduit (unless specific types) are typically restricted due to lack of sealed integrity.

Memory trick: Hazardous zones demand tough wires and seals, no flimsy stuff, that's how it feels.

A calculation performed to ensure that the voltage drop in a single-phase circuit does not exceed recommended limits (typically 3% for branch circuits), preventing inefficient operation and equipment damage.

• Uses the formula CM = (2 * K * I * L) / VD.
• K-factor for copper is 12.9 at 75°C.
• Crucial for proper equipment function and energy efficiency.

Memory trick: Voltage Drop: 'V'ery 'D'ifficult if you don't 'K'now the formula.

The requirement in the NEC (210.20(A), 215.2(A)(1)) to size overcurrent protective devices (OCPDs) for continuous loads at not less than 125% of the continuous load current.

• A continuous load operates for 3 hours or more.
• OCPDs must be sized at 125% of the continuous load current.
• This factor accounts for heat buildup in the OCPD.

Memory trick: Continuous loads need an 'OCPD' that's '125' percent strong to avoid 'OVER'heating.

When determining the VA for continuous loads (operating for 3+ hours) to size an OCPD, the actual VA load must be multiplied by 125%.

• Continuous load: max current for 3+ hours
• OCPD must be sized at 125% of continuous current
• Calculated VA = actual VA * 1.25

Memory trick: VA for continuous loads needs a 'quarter-more' for safety.

The maximum current a conductor can carry continuously under specified conditions without exceeding its temperature rating, determined by NEC Table 310.16 and restricted by NEC 240.4(D) for small conductors.

• NEC 240.4(D) limits OCPD for small conductors.
• Conductor ampacity must be equal to or greater than the branch circuit OCPD.
• Temperature rating of insulation affects ampacity (e.g., 60°C, 75°C, 90°C).

Memory trick: Ampacity for branch circuits: 'RATED' for the 'BREAKER', 'TEMP'erature matters.

Type UF (Underground Feeder) cable, suitable for direct burial, has specific minimum cover requirements based on voltage, overcurrent protection, and location (e.g., under a driveway, residential property).

• Direct burial cable
• Requires specific cover depths per NEC Table 300.5
• GFCI protection can reduce required depth in some scenarios

Memory trick: Under Flow, find the right Footprint for buried wires.

An electrical blueprint symbol indicating a duplex receptacle designed for outdoor or wet locations, protected against moisture and environmental elements.

• Standard duplex symbol (circle with two horizontal lines).
• Annotated with 'WP' for weatherproof.
• Requires a suitable enclosure and/or GFCI protection (depending on location).

Memory trick: Blueprint 'SYMBOLS' tell a story: 'WP' means rain can't stop the power.

The overcurrent protective device (OCPD) for a hermetic refrigerant motor-compressor branch circuit must be sized based on the branch-circuit selection current (BCSC) or rated-load current (RLC), ensuring it can handle starting current but also protect against overcurrent.

• OCPD must be rated for at least 125% of the BCSC or RLC.
• Maximum OCPD size is 225% of BCSC or 175% of RLC.
• Must use the next higher standard OCPD size if calculated value is not standard.

Memory trick: Cool circuits need precise protection.

The minimum VA load assigned to each general-purpose receptacle outlet in commercial occupancies for the purpose of calculating feeder and service loads, as specified by NEC Article 220.

• 180 VA per single or multiple receptacle on one yoke.
• Applies to general-purpose receptacles, not dedicated ones.
• Used in feeder/service calculations before demand factors.

Memory trick: Commercial outlets: '180' VA is the 'MIN'imum 'LOAD'.

The sum of the volt-ampere (VA) ratings of all electrical equipment and loads connected to a wiring system or service, before applying any demand factors.

• Represents the maximum potential load if all equipment operates simultaneously.
• Used as a starting point for load calculations.
• Demand factors are applied to this value to determine the actual service or feeder size.

Memory trick: Connect ALL the lights and plugs for the total picture.

Flexible metal conduit (FMC) fill limits are specified in NEC Annex C tables, similar to rigid conduits, to ensure proper conductor installation and prevent overheating.

• FMC fill limits are generally found in tables like C.3 for specific conductor types and sizes.
• The 40% fill rule applies to FMC with three or more conductors.
• Overfilling FMC can damage conductors during installation and lead to overheating.

Memory trick: Flexible conduit, like a noodle, has fill limits, don't be a doodle.

Wiring methods in Class I, Division 1 hazardous locations (where ignitable concentrations of flammable gases or vapors exist under normal operating conditions) must be explosionproof to contain internal explosions and prevent ignition of the surrounding atmosphere.

• Governed by NEC Article 501
• Requires explosionproof wiring methods
• Threaded RMC/IMC with explosionproof fittings is common

Memory trick: In Class One, Division One, only Robust, Resilient Raceways Rule.

The sizing of a Grounding Electrode Conductor (GEC) connected to a concrete-encased electrode (Ufer ground) has a specific minimum requirement of 4 AWG copper, irrespective of the service conductor size, as long as the service conductors are not exceptionally large.

• Refer to NEC Table 250.66
• Concrete-encased electrodes (Ufer grounds) have specific GEC sizing rules
• Minimum 4 AWG copper for Ufer ground

Memory trick: Grounding Electrodes: Match the Metal to the Method.

The minimum clear distance required in front of electrical equipment to ensure safe operation, maintenance, and access for personnel.

• Governed by NEC 110.26(A)(1).
• Depth varies based on voltage to ground and conditions on the opposite side.
• Ensures worker safety from arc flash and shock hazards.

Memory trick: Work Smart, Stay Apart.

NEC Annex C tables provide pre-calculated conduit fill percentages for common conductor types and sizes, simplifying conduit sizing.

• Annex C tables are used when all conductors in a raceway are of the same type and size.
• These tables automatically account for the 40% fill limit for three or more conductors.
• Using Annex C can save time compared to manual calculations based on conductor and conduit cross-sectional areas.

Memory trick: Conduit's size, for wires' ride, Annex C's guide, no need to hide.

Branch-circuit conductors for a hermetic refrigerant motor-compressor must have an ampacity not less than 125% of either the motor-compressor's rated-load current (RLC) or the branch-circuit selection current (BCSC), whichever is greater.

• Applies to hermetic motor-compressors (HVAC, refrigeration).
• Compare (RLC × 1.25) vs. BCSC.
• Take the greater of these two values.
• Multiply that greater value by 1.25 for final conductor ampacity.

Memory trick: Hermetic's Current, Compare and Multiply.

NEC Table 250.66 specifies the minimum size of the grounding electrode conductor (GEC) based on the size of the largest ungrounded service-entrance conductor or equivalent area for parallel conductors.

• The GEC protects the electrical system from overvoltages and lightning.
• Different GEC sizes are required for connection to different types of grounding electrodes (e.g., ground rod, concrete-encased electrode, water pipe).
• The table provides separate columns for copper and aluminum/copper-clad aluminum GECs.

Memory trick: GEC size, for grounding's might, Table 250.66, sets it right!

The process of sizing an overcurrent protective device (OCPD) for a load that does not operate for 3 hours or more, where the OCPD rating can be equal to or greater than the calculated load current.

• A non-continuous load operates for less than 3 hours.
• OCPD rating can be 100% of the calculated load current.
• No 125% multiplier is applied for non-continuous loads.

Memory trick: Non-continuous: 'NO' extra 'PERCENT' for the OCPD.