ICC T17 Journeyman Electrician Exam (2020 NEC)

Type AC bends shall have an inner-edge radius not less than five times the cable diameter, while interlocked-armor/corrugated-sheath Type MC requires not less than seven times the external diameter of the metallic sheath (e.g., 25 mm cable = 175 mm/7 in.).

Table 310.15(C)(1) applies a 70 percent ampacity adjustment factor for 7–9 current-carrying conductors and a 50 percent adjustment factor for 10–20 current-carrying conductors.

For AC polyphase motors other than wound-rotor, the nontime-delay fuse maximum is 300 percent of full-load current, while the dual-element time-delay fuse maximum is 175 percent of full-load current.

The table maximum for an inverse time breaker is 250 percent of motor full-load current; if the motor will not start, the rating may be increased but shall in no case exceed 400 percent of full-load current for motors of 100 A or less (300 percent for motors above 100 A) — it is not simply moved to the next standard size.

A one-family dwelling's feeder disconnecting means shall be rated not less than 100 amperes, 3-wire, while all installations other than one-circuit, two-circuit, or one-family dwelling disconnects shall be rated not less than 60 amperes (a detached garage fed by a feeder falls in the 60-ampere 'all others' category unless it serves as the dwelling's main disconnect).

Under 220.82(B) the general calculated load is not less than 100 percent of the first 10 kVA plus 40 percent of the remainder, whereas under 220.83(A), where no additional air-conditioning or electric space-heating equipment is installed, the first 8 kVA of existing and new load is taken at 100 percent with the remainder at 40 percent.

For spans not over 1000 volts nominal, the clearance is not less than 3.0 m (10 ft) where the voltage does not exceed 150 volts to ground and the area is accessible to pedestrians only, but not less than 5.5 m (18 ft) over public streets, alleys, roads, parking areas subject to truck traffic, nonresidential driveways, and other land traversed by vehicles.

GFCI protection is required for dwelling-unit receptacles serving countertop surfaces, and AFCI protection is separately required for all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets in dwelling unit kitchens — both apply to these receptacles.

On a 4-wire delta system with the midpoint of one phase winding grounded, the conductor with the higher phase voltage to ground must be durably and permanently marked orange (or other effective means), while the grounded neutral conductor is white or gray.

The general free conductor rule is 150 mm (6 in.), but where the opening to the outlet, junction, or switch point is less than 200 mm (8 in.) in any dimension, each conductor must also be long enough to extend at least 75 mm (3 in.) outside the opening.

In ducts specifically fabricated for environmental air, FMC is permitted in lengths not to exceed 1.2 m (4 ft) to connect physically adjustable equipment, while in other spaces used for environmental air FMC is a generally permitted wiring method without that specific length limitation.

Conductors must have an ampacity of at least 125 percent of the rated-load current, while the protective device is permitted at not more than 175 percent of the rated-load current, increasable to not more than 225 percent only if the device will not carry the motor's starting current.