Free OK Journeyman Electrician Exam Flashcards

The licensed electrical contractor of record pulls the permit and schedules the required inspection, not the journeyman performing the work. Work done without the required permit and inspection can be rejected by the jurisdiction, creating liability for the contractor and the property owner even when the journeyman's work itself was code-compliant.

The opening around the penetration must be firestopped using an approved method so the assembly keeps its original fire-resistance rating. This rule exists because an unsealed penetration can let fire and smoke spread far faster than the wall or floor was designed to allow.

R = E / I = 240 / 20 = 12 ohms. P = E x I = 240 x 20 = 4,800 watts. Ohm's Law and Watt's Law together let you solve for any one unknown -- voltage, current, resistance, or power -- once you know the other two.

Every branch sees the same voltage as the source, but current divides unequally: the lowest-resistance branch carries the most current. Total circuit current equals the sum of the individual branch currents.

Line voltage = phase voltage x the square root of 3 (about 1.732). Here, 120V x 1.732 is approximately 208V. This relationship is why a wye-connected three-phase system lists two different voltages instead of one.

Convert to kilowatts and multiply: 1.5 kW x 4 hrs x 30 days = 180 kWh. Then 180 kWh x $0.12 = $21.60. Always convert watts to kilowatts before multiplying by a per-kWh utility rate.

Holiday and decorative lighting under 590.3(B) is limited to 90 days. Construction-site temporary wiring has no fixed day limit -- it may stay in place for the duration of the work but must be removed immediately once the construction, remodeling, or the need for it ends (590.3(D)).

3 feet for the 120/240V panel and 3.5 feet for the 480Y/277V panel. The table is entered by voltage to GROUND, not line-to-line voltage: 120V to ground falls in the 0-150V row (3 feet under all three conditions), while 277V to ground falls in the 151-600V row (3, 3.5, and 4 feet for Conditions 1, 2, and 3). Concrete, brick, and tile walls count as grounded.

30 inches, or the width of the equipment itself, whichever is greater. The space must also be wide enough to let any equipment door or hinged panel open at least 90 degrees.

6.5 feet (78 inches), measured from the floor, grade, or platform -- or the height of the equipment itself if that is taller. An exception lets service equipment or panelboards rated 200A or less in EXISTING dwelling units stay in spaces with less headroom.

The 60 degree C column, unless the equipment is listed and marked for higher-temperature conductors (many breakers and panels are marked 75 degrees C). For equipment rated over 100A, or conductors larger than 1 AWG, the 75 degree C column is the default. Either way, the termination rating caps the usable ampacity even when the insulation is rated 90 degrees C -- the 90 degree C column is used only for adjustment and correction math.

'Listed' (Article 100) means the equipment appears on a list published by an organization acceptable to the authority having jurisdiction -- in practice a recognized testing laboratory -- that evaluates products against safety standards and periodically inspects production. NEC 110.3(B) requires listed or labeled equipment to be installed and used per any instructions included in the listing or labeling, which turns the manufacturer's installation instructions into an enforceable code requirement.

Oklahoma's rule (OAC 748:20-10-8) keeps the base 210.8(F) requirement -- GFCI protection for dwelling outdoor outlets on single-phase branch circuits rated 150 volts or less to ground and 50 amperes or less -- but exempts lighting outlets (other than those covered by 210.8(C)) and listed HVAC equipment from that GFCI requirement.

The default in 230.71(A) is ONE disconnecting means per service. Two to six service disconnects are permitted only under 230.71(B), which requires each one to be in its own enclosure, its own panelboard enclosure, its own barriered switchboard section, or its own switchgear or metering-center compartment. Six service breakers side by side in a single panelboard -- legal under the old 'six-handle rule' -- has not been permitted since the 2020 NEC.

No more than 3% on the branch circuit (or on the feeder) alone, and no more than 5% total for feeder plus branch circuit to the farthest outlet, per the informational notes in 210.19 (branch circuits) and 215.2 (feeders). Informational notes are explanatory, not enforceable (90.5(C)) -- but a few sections do set mandatory limits, such as 647.4(D) for sensitive electronic equipment and 695.7 for fire pumps.

Under 210.19(A), the conductor's ampacity -- before any adjustment or correction factors -- must be at least 125% of the continuous load plus 100% of any noncontinuous load. The exception is an assembly, including its overcurrent device, that is listed for operation at 100% of its rating. The same 125% factor sizes the overcurrent device under 210.20(A), so a 16A continuous load needs a 20A circuit.

A means must simultaneously disconnect all of the circuit's ungrounded conductors at the panel where it originates -- separate single-pole breakers aren't enough unless they're joined by an identified handle tie. This prevents a worker from de-energizing only part of a shared-neutral circuit.

14 AWG: 15A. 12 AWG: 20A. 10 AWG: 30A. These caps apply regardless of what a higher ampacity-table column shows for the insulation rating, so a 30A breaker on 12 AWG copper feeding general-purpose receptacles is a violation. The rule yields only where 240.4(E) or (G) specifically permits it, such as motor and air-conditioning circuits sized under Articles 430 and 440.

A 70A device. Table 240.6(A) has no 65A standard rating (it jumps from 60A to 70A), and 240.4(B) permits the next higher standard rating when the conductor ampacity falls between sizes, the device is rated 800A or less, and the conductors do not supply a multi-receptacle branch circuit for cord-and-plug-connected portable loads. Above 800A, 240.4(C) flips the rule: conductor ampacity must equal or exceed the device rating.

10-foot tap: ampacity not less than the calculated load and not less than the rating of the equipment or overcurrent device it supplies -- and, when the tap leaves the enclosure where it is made, at least one-tenth of the feeder overcurrent device rating. 25-foot tap: ampacity at least one-third of the feeder overcurrent device rating, terminating in a single breaker or set of fuses that limits the load to the tap's ampacity. Both must be protected from physical damage, such as by a raceway.

Bathrooms, showering facilities, and locker rooms with showering facilities (240.24(E)) -- the 2023 NEC widened this from dwelling-type bathrooms to bathrooms in every occupancy. Also off-limits: the vicinity of easily ignitible material such as clothes closets (240.24(D)), over the steps of a stairway (240.24(F)), and anywhere exposed to physical damage (240.24(C)). Supplementary overcurrent protection is exempt from the bathroom rule.

2 AWG copper. Table 250.66 sizes the GEC by the largest ungrounded service-entrance conductor: 2 AWG or smaller copper service conductors need only an 8 AWG copper GEC, while conductors over 3/0 through 350 kcmil copper (which 300 kcmil falls within) require a 2 AWG copper GEC.

At least 8 feet long. A stainless steel or coated steel rod must be at least 5/8 inch in diameter unless it is listed, in which case a smaller listed diameter (commonly 1/2 inch) is permitted -- it's the listing, not the base metal, that unlocks the thinner rod.

At least 20 feet of either bare, zinc-galvanized, or other electrically conductive coated steel rebar 1/2 inch or larger in diameter (one continuous length, or pieces tied together to reach 20 feet), or bare copper conductor 4 AWG or larger -- encased in at least 2 inches of concrete within a footing or foundation that is in direct contact with the earth. Epoxy-coated rebar, or concrete separated from the soil by a vapor barrier, does not qualify.

No. NEC 250.52(B) specifically bars metal underground gas piping systems, along with aluminum, from being used as a grounding electrode, even though other qualifying metal underground piping -- such as a metal water pipe -- can serve that role under 250.52(A).

Grounding connects a system or piece of equipment to the earth through a grounding electrode. Bonding joins metal parts together electrically so they stay at the same potential and can carry fault current back to the source -- grounding ties the system to earth, while bonding ties equipment together.

Plain THHN is rated 90 degrees C but only for dry or damp locations, while plain THWN is rated 75 degrees C and approved for wet locations. THWN-2 dual-rates the same conductor at 90 degrees C for BOTH wet and dry locations, so dual-marked wire gives installers the higher ampacity column without giving up wet-location approval.

Type UF's sheath is flame-retardant and moisture-, fungus-, and corrosion-resistant, and 340.10 expressly permits direct burial. Type NM is limited to normally dry locations, and 334.12(B) bars it from wet or damp locations -- which includes the inside of an underground raceway, because 300.5(B) treats that interior as a wet location. Sleeving NM in buried conduit does not fix the problem.

Type AC cable has an internal bonding strip (copper or aluminum) in intimate contact with its interlocked metal armor; together they lower the impedance enough for the armor to qualify as an equipment grounding conductor under 250.118. The strip alone is not an EGC and is simply folded back or cut off at terminations. Ordinary interlocked-armor Type MC cable instead carries a separate wire-type equipment grounding conductor.

Type MV cable is rated 2,001 volts up to and including 35,000 volts, nominal. Because that is above the 2,000V ceiling of the ordinary building-wire rules in Article 310, medium-voltage conductors and cable have their own article -- Article 311 in the 2023 NEC (older editions used Article 328).

14 AWG: 2.00 cubic inches. 12 AWG: 2.25 cubic inches. 10 AWG: 2.50 cubic inches. Each conductor is counted at its own size. Extras are added on top: one allowance for all internal clamps (largest conductor in the box), two allowances per device yoke (largest conductor connected to that device), and one allowance for up to four equipment grounding conductors plus a 1/4 allowance for each additional one (largest EGC in the box).

40% fill is the limit for three or more conductors, per NEC Chapter 9, Table 1. A single conductor is allowed up to 53% fill, and exactly two conductors are limited to 31% -- these percentages leave room for heat dissipation and keep conductors pullable without insulation damage.

360 degrees total -- the equivalent of four 90-degree (quarter) bends. This limit applies within each raceway article (EMT, RMC, PVC, and others) and exists so conductors can still be pulled through the run without damaging their insulation.

EMT and RMC are metallic and, when properly installed with listed fittings, can themselves serve as the equipment grounding path under NEC 250.118. PVC is nonconductive, so it cannot provide that path -- a dedicated conductor-type equipment grounding conductor must be installed with the circuit conductors inside the PVC run.

Class I locations are those where flammable gases or flammable or combustible liquid-produced vapors may be present in the air in ignitible quantities -- think a paint spray booth or fuel-dispensing area. Class II locations instead involve combustible dust, such as a grain elevator or flour mill. Class III, a separate category, covers easily ignitible fibers or flyings that are not normally suspended in the air, such as in a textile mill.

Division 1 means the flammable gas, dust, or fiber hazard is present continuously or is likely to exist under normal operating conditions. Division 2 means the hazard is present only under abnormal conditions, such as equipment failure or a ruptured containment system.

The perimeter surface to be bonded extends 3 feet horizontally beyond the inside walls of the pool and includes both paved and unpaved surfaces. That perimeter bonding -- structural reinforcing steel or a copper conductor such as an 8 AWG bare solid copper ring -- must attach to the pool's reinforcing steel or copper conductor grid at a minimum of four points uniformly spaced around the pool's perimeter.

The branch circuit needs both an effective grounding path through a metallic raceway or metal cable armor AND a separate insulated copper equipment grounding conductor run with the circuit conductors. This redundancy exists because a patient care space has a much lower tolerance for a grounding-path failure than ordinary occupancies.

It must NOT be mounted in or on the mobile home. It must be located in sight from the home and no more than 30 feet from its exterior wall, so the occupant can reach the disconnect without entering or climbing onto the structure.

A Class 2 or Class 3 circuit is fed by a listed power source -- typically a Class 2 transformer or power supply -- that limits voltage and current enough that the wiring doesn't need branch-circuit-style overcurrent protection or insulation. Thermostat and doorbell wiring are common Class 2 examples. In the 2023 NEC, Article 725 covers only Class 2 and Class 3 circuits; Class 1 circuits moved to the new Article 724.

At least 1/2 inch between its recessed parts and combustible material (410.116(A)(1)), and no thermal insulation above it or within 3 inches of its enclosure, wiring compartment, ballast, transformer, LED driver, or power supply (410.116(B)). A Type IC luminaire is identified for insulation contact, so its recessed parts may touch both combustible material and insulation.

A surface-mounted incandescent or LED luminaire with a completely enclosed light source needs at least 12 inches of clearance from the closet's storage space under NEC 410.16(C). A recessed incandescent or LED luminaire with a completely enclosed light source, or a fluorescent luminaire (surface or recessed), needs only 6 inches. Incandescent luminaires with open or partially enclosed lamps and pendant luminaires are not permitted anywhere in a clothes closet (410.16(B)).

Cord-connected luminaires, chain-, cable-, or cord-suspended luminaires, lighting track, pendants, and ceiling-suspended (paddle) fans may not have any part within a zone measured 3 feet horizontally and 8 feet vertically from the top of the bathtub rim or shower stall threshold. The zone includes the space directly over the tub or shower, where any permitted luminaire must be marked for damp locations -- or wet locations if subject to shower spray.

Three options: at the point the feeder or branch circuit enters the sign enclosure, sign body, or pole; within sight of the sign; or, for a sign run by an external controller, within sight of (or in the same enclosure as) the controller. Whenever the disconnect is out of the line of sight from any section that can be energized, it must be lockable in the open position per 110.25, so the sign can be serviced without relying on someone else to keep the circuit open.

A disconnecting means must be added at the time the ballast is replaced. The rule applies indoors, in other than dwellings, to fluorescent luminaires that use double-ended lamps and have ballasts that can be serviced in place: each needs a disconnect, internal or external to the luminaire, so the ballast can be de-energized without shutting off the whole circuit. On a multiwire branch circuit the disconnect must open all supply conductors to the ballast, including the grounded conductor (410.130(G)(2)).

6 feet or more above a lower level for an unprotected side or edge of a walking/working surface (29 CFR 1926.501(b)(1)), satisfied by guardrails, safety nets, or a personal fall arrest system. More than 10 feet above a lower level for employees on a scaffold (29 CFR 1926.451(g)(1)). Body belts have not been acceptable as part of a personal fall arrest system since January 1, 1998, so fall arrest means a full-body harness.

5 feet or more, unless the excavation is made entirely in stable rock, or it is less than 5 feet deep and a competent person's examination finds no indication of a potential cave-in. Trench inspections by a competent person are required daily and after any event, like heavy rain, that could affect stability.

Not less than 125% of the motor's full-load current (FLC) taken from NEC Tables 430.247 through 430.250 -- not the nameplate current (430.6(A)(1)). For example, a 5 hp, 230V single-phase motor has a Table 430.248 FLC of 28A, so its conductors need at least 35A of ampacity. Nameplate current is used instead for sizing the motor's separate overload protection (430.6(A)(2)).

NEC Article 100 defines 'in sight from' as visible and located no more than 50 feet away. A motor controller's disconnect (NEC 430.102(A)) must normally be located in sight from the controller, unless the installation qualifies for one of the code's specific exceptions.

Only for a single-phase transformer with a 2-wire (single-voltage) secondary or a three-phase delta-delta transformer with a 3-wire secondary, and only if the primary device does not exceed the secondary conductor ampacity multiplied by the secondary-to-primary voltage ratio. With other secondaries, such as 120/240V 3-wire or 208Y/120V 4-wire, unbalanced loading can overload one secondary conductor without tripping the primary device, so those conductors need their own protection under 240.21(C).