NE Journeyman Electrician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Ohm's law

E = I × R, where E is voltage in volts, I is current in amperes, and R is resistance in ohms. In AC circuits impedance Z replaces R.

Three-phase power formula

For a balanced three-phase load, P = √3 × E_line × I_line × power factor. This gives real power in watts when line voltage and line current are used.

Conductor resistance formula

R = K × L / CM, where K is the resistivity constant (12.9 for copper, 21.2 for aluminum), L is length in feet, and CM is circular mils.

Voltage drop single phase

VD = 2 × K × I × L / CM for a single-phase circuit, where the factor 2 accounts for the outgoing and return conductors. Three-phase uses √3 instead of 2.

NM-B cable use

Nonmetallic-sheathed cable is permitted in one- and two-family dwellings and normally dry locations. It must be protected from physical damage and cannot be embedded in masonry.

EMT support interval

Electrical metallic tubing must be supported within 3 ft of each box or fitting and at intervals not exceeding 10 ft along the run.

Liquidtight flex limit

Liquidtight flexible metal conduit is limited to 6 ft between a box or fitting and the equipment it supplies unless the circuit is protected by the tap rules.

Direct burial cable

Type UF cable is suitable for direct burial at the depths specified in the burial table and requires supplemental protection where it emerges from the ground.

Grounding electrode conductor size

The grounding electrode conductor to a rod, pipe, or plate electrode is not required to be larger than 6 AWG copper or 4 AWG aluminum.

Main bonding jumper

The main bonding jumper connects the grounded conductor to the equipment grounding conductor at the service disconnect and is sized per the service conductor table.

Equipment grounding conductor sizing

Equipment grounding conductors are sized from the EGC table based on the rating of the overcurrent device protecting the circuit, not solely on conductor ampacity.

Separately derived system bonding

A separately derived system requires a system bonding jumper and a grounding electrode conductor connected to a grounding electrode at the source location.

Standard OCPD ratings

Standard overcurrent device ratings include 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, and 400 A.

Next-higher-size rule

Where conductor ampacity does not match a standard OCPD rating, the next higher standard rating may be used only if it does not exceed 800 A.

Continuous load OCPD rule

The overcurrent device must be at least 125% of the continuous load plus 100% of the noncontinuous load for the circuit it protects.

Series-rated system

A series-rated combination requires the downstream overcurrent device to be listed and marked for use with the specific upstream device, establishing the equipment short-circuit current rating.

Small-appliance branch circuits

A dwelling kitchen requires at least two 20 A small-appliance branch circuits, and these circuits may not supply lighting outlets.

General lighting load dwelling

The general lighting load for a dwelling unit is 3 VA per square foot of floor area, with demand factors applied to the portion above 3,000 VA.

Receptacle spacing dwelling

In dwelling units, no point along the floor line may be more than 6 ft from a receptacle, and any wall space 2 ft or wider requires a receptacle.

Service calculation steps

Compute general lighting, small-appliance, laundry, and fixed appliance loads; apply demand factors; add the largest motor at 25%; then size service and feeder conductors.

Motor branch-circuit conductors

Motor branch-circuit conductors must have an ampacity of at least 125% of the motor full-load current taken from the motor tables.

Motor disconnecting means

The motor disconnecting means must be within sight of the motor and controller, capable of being locked open, and rated at least 115% of motor full-load current.

Motor overload protection

Overload protection is sized from the motor nameplate current and protects the motor from overload, while the branch breaker protects conductors from short circuits.

HVAC nameplate ratings

HVAC equipment nameplates give minimum circuit ampacity and maximum overcurrent protection, which govern conductor sizing and breaker selection for the unit.

Transformer primary protection

Transformer primary overcurrent protection is typically sized at 125% of primary current per the transformer table, with secondary protection sized at 125% of secondary current.

Hazardous location classification

Hazardous locations are classified by Class, Division, and Group, and equipment must be listed and marked for the specific class, division, and group.

Class I seal requirement

In Class I locations, conduit seals are required at boundaries and within specified distances, and wiring methods include threaded rigid metal conduit and listed MC cable.

Box fill calculation

Box fill is determined from the box volume in cubic inches, with each conductor counted per the box fill table and grounding conductors counted as one.

Raceway fill 40 percent

For three or more conductors, the sum of conductor cross-sectional areas must not exceed 40% of the raceway internal cross-sectional area.

Conductor ampacity adjustment

Ampacity is adjusted for ambient temperature and for the number of current-carrying conductors in a raceway or cable, applying the adjustment factors to table ampacity.

Nebraska electrical licensing

Nebraska electrical licensing is administered by the State Electrical Division, which adopts the electrical code and enforces licensing through the State Electrical Board.

Nebraska journeyman supervision

A Nebraska journeyman electrician must work under the supervision of a licensed master electrician or contractor, and a contractor license is required to offer electrical contracting services.