WI Electrician flashcards

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

Ohm's law

Voltage equals current multiplied by resistance (E = I × R). Power equals current times voltage. These relationships let you solve for any missing value when two of the three quantities are known.

Series circuit current

In a series circuit the same current flows through every component. Total resistance is the sum of individual resistances, and the source voltage divides across them in proportion to resistance.

Parallel circuit voltage

In a parallel circuit the voltage across each branch is the same and equal to the source voltage. Branch currents add, and total resistance is less than the smallest branch resistance.

Three-phase power formula

For a balanced three-phase load, power equals the square root of three times line voltage times line current times power factor. This applies to both wye and delta balanced loads.

Voltage drop formula

For a single-phase two-wire circuit, voltage drop equals two times the resistivity constant times current times length, divided by conductor circular mils. The factor two accounts for both conductors.

Box fill calculation

Box fill counts each conductor entering the box, each device yoke, and each grounding conductor, converted to volume. The total must not exceed the box's marked cubic-inch capacity.

Motor branch-circuit sizing

Motor branch-circuit conductors are sized at not less than 125 percent of the motor full-load current rating from the appropriate table, not from the nameplate alone.

Conductor ampacity adjustment

Ampacity is reduced for elevated ambient temperature and for more than three current-carrying conductors in a raceway or cable. Both adjustments are applied to the table ampacity.

Service load calculation

The service disconnect rating must be at least the calculated load, and the service conductors must carry it. Loads are computed per Article 220 and demand factors applied.

Next higher overcurrent rating

A standard overcurrent device rating higher than the calculated load may be used only where the calculated load does not exceed the device rating and the conductors are protected.

Dwelling lighting load

For a single-family dwelling, the general lighting load is computed at three volt-amperes per square foot of floor area, then demand factors are applied to the total.

Grounding electrode conductor size

The grounding electrode conductor is sized from the table keyed to the largest service conductor, not from the rating of the service overcurrent device.

Interrupting rating requirement

The interrupting rating of an overcurrent device must be at least the available fault current at its point of application, so it can safely clear a fault.

Raceway conductor fill

Conductor fill in a raceway is limited to 40 percent for three or more conductors, 53 percent for one conductor, and 31 percent for two conductors.

Kitchen small-appliance circuits

At least two 20-ampere branch circuits must supply the kitchen, pantry, and dining area receptacle outlets. These circuits may also serve other specified outlets.

Laundry branch circuit

At least one 20-ampere branch circuit must supply the laundry receptacle outlet or outlets. It may supply only the laundry area outlets permitted by the Code.

Bathroom receptacle circuit

Bathroom receptacle outlets must be supplied by at least one 20-ampere branch circuit. That circuit may not supply outlets outside the bathroom.

GFCI protection locations

Ground-fault circuit-interrupter protection is required for receptacle outlets in bathrooms, garages, outdoors, kitchen countertops, and unfinished basements in dwelling units.

AFCI protection requirement

Arc-fault circuit-interrupter protection is required for most 120-volt, 15- and 20-ampere branch circuits supplying outlets in dwelling units, with limited exceptions.

Receptacle spacing rule

In habitable rooms, receptacle outlets must be installed so that no point along the floor line is more than six feet from a receptacle outlet.

Tamper-resistant receptacles

A 125-volt, single-phase, 15- or 20-ampere receptacle outlet in a dwelling unit must be tamper-resistant where the Code requires it for that location.

Motor disconnecting means

The motor disconnecting means must be located within sight of the motor controller and must open all ungrounded conductors of the motor circuit.

Motor overload protection

Motor overload protection is sized to the motor's nameplate full-load current and service factor. It is separate from branch-circuit short-circuit and ground-fault protection.

Motor short-circuit protection

Motor branch-circuit short-circuit and ground-fault protection may be a nontime-delay fuse, time-delay fuse, or circuit breaker, each sized as a percentage of full-load current.

Motor controller rating

A controller must be capable of starting and stopping the motor it serves and must have a horsepower rating not less than the motor's rating.

Class I location definition

Class I locations are those in which flammable gases or vapors may be present in quantities sufficient to produce explosive or ignitable mixtures. Equipment must be marked for the class, division, and group.

Motor conductor sizing

Motor circuit conductors are sized at 125 percent of the motor full-load current. The overload device protects the motor, and the branch-circuit device protects the conductors.

SPS 316 adoption

SPS 316 adopts the National Electrical Code with Wisconsin amendments. Where the state rule and the NEC differ, the state rule governs the installation.

Wisconsin electrical permit

Electrical work in Wisconsin requires a permit from the local municipality, or from the Department of Safety and Professional Services where no local program exists.

Wisconsin electrician credentials

Electricians must be credentialed by the Department. Journeyman and master electrician are separate credential categories with different scope and supervision requirements.

Concealed work inspection

Work must be inspected by the authority having jurisdiction before it is concealed. Covering uninspected work can require removal and re-inspection at the installer's expense.

Equipment grounding conductor size

Equipment grounding conductors are sized from the table keyed to the rating of the overcurrent device protecting the circuit, not from the circuit conductor size alone.