Idaho Low Voltage Practice flashcards

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

Working space width

NEC 110.26(A)(2) requires at least 30 inches of clear width in front of electrical equipment, or the width of the equipment if wider, for the full depth of the working space.

Readily accessible definition

Article 100 defines readily accessible as capable of being reached quickly for operation without climbing over or removing obstacles, or requiring the use of portable ladders.

Continuous load definition

A continuous load is a load expected to continue for three hours or more. Branch-circuit conductors and overcurrent devices must be sized at 125 percent of it.

NM cable support spacing

NEC 334.30 requires nonmetallic-sheathed cable to be secured within 12 inches of boxes and at intervals not exceeding 4 1/2 feet along the run.

EMT support requirements

NEC 358.30 requires EMT to be securely fastened within 3 feet of each box and at intervals not exceeding 10 feet, with bends limited to 360 degrees between boxes.

Conductors in parallel rule

NEC 310.10(H) permits parallel conductors only if they are 1/0 AWG or larger, identical in length, material, size, insulation, and terminated in the same manner.

Class 2 circuit limits

Class 2 circuits are power-limited to 30 volts and 100 volt-amperes or less, and their power source must be listed per NEC 725.121.

Communications separation distance

NEC 800.133 requires at least 2 inches of separation between communications cables and power conductors, unless a barrier or a Chapter 3 raceway is used.

Plenum cable requirement

NEC 300.22(C) requires listed plenum-rated cable, such as CMP, or metal raceway in environmental air spaces; NM cable and PVC conduit are prohibited there.

Grounding electrode conductor sizing

Table 250.66 sizes the grounding electrode conductor from the largest service-entrance conductor. For 2 AWG copper service conductors, an 8 AWG copper conductor is required.

Equipment grounding conductor sizing

Table 250.122 sizes the equipment grounding conductor from the overcurrent device rating. A 20-ampere circuit requires 12 AWG copper; a 100-ampere circuit requires 8 AWG copper.

Concrete-encased electrode

NEC 250.52(A)(3) recognizes at least 20 feet of 1/2-inch reinforcing steel or 4 AWG bare copper encased in concrete as a grounding electrode.

Small conductor overcurrent limits

NEC 240.4(D) limits 14 AWG copper to 15 amperes, 12 AWG to 20 amperes, and 10 AWG to 30 amperes unless a specific exception applies.

Next size up rule

NEC 240.4(B) permits the next higher standard overcurrent device rating where conductor ampacity does not match a standard rating, limited to 800 amperes and not for multioutlet branch circuits.

Conductor bundling adjustment

Table 310.15(C)(1) requires ampacity adjustment when more than three current-carrying conductors share a raceway or cable: 80 percent for four to six conductors, 70 percent for seven to nine.

Box fill conductor counting

NEC 314.16(B) counts each conductor entering the box once, each device yoke as two conductors of the largest size, and all equipment grounding conductors as one.

Pull box straight pull sizing

NEC 314.28(A)(1) requires a straight-pull box length of at least eight times the trade size of the largest raceway entering the box.

Direct burial depth

NEC 300.5(A) requires 24 inches of cover for direct-buried conductors, 18 inches for residential 120-volt GFCI branch circuits, and 6 inches under a concrete slab.

Class I Division 1 meaning

In a Class I Division 1 location, ignitable concentrations of flammable gases or vapors are present under normal operating conditions, requiring explosion-proof equipment and sealing fittings.

Patient care redundant ground

NEC 517.13 requires receptacles in patient care areas to have a redundant ground path: a metal raceway or armored cable plus an insulated copper equipment grounding conductor.

Pool equipotential bonding

NEC 680.26 requires an equipotential bonding grid around a pool, bonding metal parts within 5 feet, using a conductor of at least 8 AWG copper.

Idaho contractor license requirement

Idaho requires an electrical contractor license for any business contracting electrical work, with a designated master electrician as the responsible licensee under Idaho Electrical Board rules.

Idaho apprentice registration

Idaho apprentice electricians must be registered with the Division of Occupational and Professional Licenses and work under the supervision of a licensed journeyman or master electrician.

Idaho permit and inspection

Idaho requires permits for electrical work, with rough-in and final inspections by the local building department under the adopted electrical code and any local amendments.

Arc flash PPE category 1

NFPA 70E Category 1 tasks require arc-rated clothing with a minimum arc rating of 4 calories per square centimeter, plus other protective equipment specified by the standard.

Lockout tagout steps

Isolate all energy sources, apply locks and tags, release stored energy, and verify the absence of voltage with a properly rated meter before beginning work.

Overhead line clearance

OSHA requires equipment and personnel to stay at least 10 feet from energized overhead lines up to 50 kilovolts, with greater distances for higher voltages.

Ohm's law and power

Ohm's law states V equals I times R. Power equals V times I, which also equals I squared times R or V squared divided by R for resistive circuits.

Single-phase voltage drop

Voltage drop equals 2 times K times I times L divided by circular mils, where K is 12.9 for copper and 21.2 for aluminum, L is length in feet, and I is amperes.

Three-phase power formula

Three-phase power equals 1.732 times voltage times current times power factor. Apparent power in volt-amperes omits the power factor term.

Motor branch conductor sizing

NEC 430.22 requires motor branch-circuit conductors to have an ampacity of at least 125 percent of the motor full-load current from Table 430.250.

Transformer current calculation

For a three-phase transformer, primary current equals kVA times 1000 divided by 1.732 times primary voltage; secondary current uses the secondary voltage the same way.