Journeyman Electrician (NEC) — All Questions

A location where combustible dust is present in ignitible concentrations is classified as which type?

• a.Class IV
• b.Class II✓
• c.Class I
• d.Class III

Class II locations are those made hazardous by combustible dust. Class I covers flammable gases and vapors and Class III covers ignitible fibers and flyings. See NEC 500.5(C).

A 15-ampere, 125-volt receptacle is installed in a damp location such as under a roofed open porch. What cover is required?

• a.A cover that is weatherproof when no attachment plug is inserted✓
• b.A cover that is weatherproof whether or not a plug is inserted
• c.No cover is required in a damp location
• d.A standard indoor wall plate

In damp locations a receptacle needs an enclosure weatherproof when a plug is not inserted; the stricter in-use cover, weatherproof with a plug inserted, is required in wet locations. See NEC 406.9(A).

Receptacles installed outdoors in wet or damp locations must be which listed type?

• a.Twist-lock
• b.Weather-resistant✓
• c.Hospital-grade
• d.Isolated-ground

Fifteen- and 20-ampere, 125- and 250-volt receptacles in damp or wet locations must be listed weather-resistant. See NEC 406.9(A) and 406.9(B).

Which of the following is a recognized equipment grounding conductor?

• a.Electrical nonmetallic tubing
• b.Rigid metal conduit installed under its article✓
• c.A nonmetallic pull string
• d.Rigid PVC conduit

Metal raceways such as rigid metal conduit, intermediate metal conduit and EMT are recognized equipment grounding conductors; nonmetallic raceways are not. See NEC 250.118.

Rigid PVC conduit requires an expansion fitting where the expected length change due to temperature is at least what value?

• a.1/8 inch
• b.1 inch
• c.1/2 inch
• d.1/4 inch✓

Expansion fittings are required for PVC conduit where the length change is expected to be 1/4 inch or more. See NEC 352.44.

How many 12 AWG conductors may be installed in a 21.0-cubic-inch box with no clamps, devices or fittings?

• a.8
• b.10
• c.9✓
• d.11

Each 12 AWG conductor requires 2.25 cubic inches: 21.0 / 2.25 = 9.33, rounded down to 9 conductors. See NEC 314.16(A) and (B).

What is the maximum permitted conductor fill of a metal wireway?

• a.31 percent
• b.53 percent
• c.20 percent✓
• d.40 percent

The conductors in a metal wireway may not fill more than 20 percent of its interior cross-sectional area. See NEC 376.22(A).

A raceway enters a building underground from an outside source. What is required at the point of entry?

• a.It must be sealed or plugged to prevent moisture from entering the building✓
• b.It must be left open for ventilation
• c.It must be filled completely with concrete
• d.It must be bonded but is never sealed

Conduits and raceways entering a building underground must be sealed or plugged with an identified compound to stop moisture and gases from entering. See NEC 300.5(G).

Type NM cable entering a single-gang nonmetallic box that has no cable clamps must be secured within what distance of the box?

• a.24 inches
• b.8 inches✓
• c.3 feet
• d.4 and 1/2 feet

Where a single-gang nonmetallic box without internal clamps is used, the NM cable must be secured within 8 inches of the box. See NEC 314.17(C) Exception and 334.30(A).

May a raceway be used as a means of support for another raceway or box?

• a.Yes, in all cases
• b.Yes, for spans under 6 feet
• c.Only where the raceway is nonmetallic
• d.No, except where the raceway is identified for that purpose or specifically permitted✓

Raceways may not be used to support other raceways, cables or nonelectrical equipment unless identified for the purpose or specifically permitted. See NEC 300.11(C).

A junction box contains four 12 AWG and three 10 AWG conductors with no devices, clamps or fittings. What minimum box volume is required?

• a.16.5 cubic inches✓
• b.17.5 cubic inches
• c.14.0 cubic inches
• d.15.75 cubic inches

Each conductor is counted at the allowance for its own size: four 12 AWG at 2.25 = 9.0, and three 10 AWG at 2.50 = 7.5, for 16.5 cubic inches. See NEC 314.16(B)(1).

What is the minimum trade size of EMT required for six 10 AWG THHN conductors?

• a.One inch
• b.Three-quarter inch✓
• c.One-half inch
• d.One and one-quarter inch

Annex C, Table C1 shows one-half-inch EMT holds five 10 AWG THHN and three-quarter-inch EMT holds ten, so three-quarter inch is the minimum for six. See NEC Annex C, Table C1.

A metal outlet box is supplied by a wiring method that includes an equipment grounding conductor. How must the box be treated?

• a.It must be left isolated from ground
• b.It must be connected to the grounded neutral bar
• c.It must be connected to the equipment grounding conductor✓
• d.It need be bonded only in a wet location

A metal box must be connected to an equipment grounding conductor so it is bonded and any fault will clear. See NEC 250.148 and 314.4.

An insulated bushing or fitting to protect conductors from abrasion is required where conductors of what size or larger enter a raceway or enclosure?

• a.1 AWG
• b.4 AWG✓
• c.8 AWG
• d.6 AWG

Where ungrounded conductors of 4 AWG or larger enter a raceway in a cabinet, box or enclosure, a fitting providing a smoothly rounded insulating surface, such as an insulating bushing, is required. See NEC 300.4(G).

In box-fill calculations, how is a device yoke or strap counted?

• a.As two conductor volume allowances, based on the largest conductor connected to the device✓
• b.It is not counted at all
• c.As one conductor volume allowance
• d.As two allowances, based on the smallest conductor

Each yoke or strap containing a device or utilization equipment is counted as two conductor volume allowances based on the largest conductor connected to it. See NEC 314.16(B)(4).