Mississippi Residential Electrician

Key Concepts

Definitions that drive sizing - Continuous load: a load where the maximum current is expected to continue for 3 hours or more (NEC 2020, Article 100). - Ampacity: the maximum current, in amperes, a conductor can carry continuously under the conditions of use without exceeding its temperature rating (NEC 2020, Article 100).

Branch-circuit conductor sizing and ampacity - Minimum conductor size for voltage ratings up to and including 2000 volts is 14 AWG copper or 12 AWG aluminum or copper-clad aluminum, except as permitted elsewhere in the Code (NEC 2020, 310.3(A)). - Termination temperature limits (NEC 2020, 110.14(C)(1)): - (a) Circuits rated 100 amperes or less, or marked for 14 AWG through 1 AWG: terminations used only for 60°C (140°F) conductors, or higher-temperature conductors whose ampacity is determined at the 60°C ampacity, or higher ratings if the equipment is listed and identified for them. For motors marked design letter B, C, or…

Mississippi Residential Electrician — 15 questions, 25% of exam

Key Concepts

Service conductors, clearances, and supports - Overhead service conductors not exceeding 300 volts to ground: minimum clearance 3.7 m (12 ft) over residential property and driveways, and commercial areas not subject to truck traffic — 230.24(B)(2). For outside branch circuits/feeders, 225.18 adds 10 ft above finished grade, sidewalks, or any platform/projection permitting personal contact (≤150 V to ground, pedestrians only), 15 ft for those same areas listed in the 12-ft classification where the voltage exceeds 300 V to ground, 18 ft over public streets, alleys, roads, parking areas subject to truck traffic and other land traversed by vehicles, 24½ ft over railroad track rails. - Vegetation such as trees shall not be used for support of overhead service conductors or service equipment — 230.10 (and 225.26 for overhead conductor spans). - Underground service conductors shall not be smaller than **8 AWG copper or…

Mississippi Residential Electrician · 5 questions (8%)

Key Concepts

Scope and conductor protection - Parts I–VII of Article 240 cover overcurrent protection not more than 1000 volts, nominal; Part VIII covers supervised industrial installations at not more than 1000 volts; Part IX covers over 1000 volts (NEC 2020, 240.1). - Conductors, other than flexible cords, flexible cables, and fixture wires, are protected per their ampacities in 310.14 unless otherwise permitted in 240.4(A) through (G) (240.4). - Next higher standard rating: permitted above conductor ampacity only if the conductors are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads, the ampacity does not correspond to a standard rating, and the next higher standard rating selected does not exceed 800 amperes (NEC 240.4(B)). The residential code states the same allowance with a limit that the next higher standard device rating does not exceed 400 amperes (IRC E3705.5.2 [240.4(B)]). - Devices…

Key Concepts

Effective ground-fault current path. The path must be a low-impedance circuit that facilitates operation of the overcurrent device or ground detector and safely carries the maximum ground-fault current likely to be imposed on it. "The earth shall not be considered as an effective ground-fault current path" (NEC 2020, 250.4(A)(5)); a parallel statement appears for ungrounded systems in 250.4(B)(4): "The earth shall not be considered as an effective fault-current path."

Grounding electrodes permitted (250.52(A)). - Metal underground water pipe in direct contact with earth for 10 ft or more, including a bonded metal well casing — 250.52(A)(1). - Metal in-ground support structure in direct contact with earth vertically 10 ft or more — 250.52(A)(2). - Concrete-encased electrode: at least 20 ft of bare/zinc galvanized steel reinforcing bars not less than 1/2 in. diameter, or bare copper not smaller than 4 AWG, encased by at least 2 in. of concrete — 250.52(A)(3). - Ground…

Mississippi Residential Electrician | 5 questions (8% of exam)

Key Concepts

Minimum size and stranding - For voltage ratings up to and including 2000 volts, the minimum conductor size is 14 AWG copper or 12 AWG aluminum or copper-clad aluminum, except as permitted elsewhere in the Code — NEC 2020, 310.3(A). - Where installed in raceways, conductors 8 AWG and larger shall be stranded, unless specifically permitted or required elsewhere to be solid — 310.3(C). - Fixture wires shall not be smaller than 18 AWG — 402.6. - Type MV cable rated 8001–15,000 volts: minimum conductor size 2 AWG copper, aluminum, or copper-clad aluminum — Table 311.12(A).

Identification and marking - An insulated grounded conductor 6 AWG or smaller shall be identified by a continuous white outer finish, a continuous gray outer finish, or three continuous white or gray stripes on other than green insulation, among other methods — 200.6(A). - The continuity of…

Key Concepts

Conduit uses. FMC shall not be used in wet locations, underground, or embedded in poured concrete or aggregate [348.12(1), (6)]. LFMC is permitted where conditions require flexibility or protection from machine oils, liquids, vapors, or solids, and for direct burial where listed and marked for the purpose [350.10]; LFMC shall not be used where subject to physical damage [350.12]. PVC used exposed in areas of physical damage shall be identified for the use — Informational Note: Type Schedule 80 is identified for areas of physical damage [352.10(F)]. PVC shall not be used where subject to ambient temperatures in excess of 50°C (122°F) unless listed otherwise [352.12(D)].

Key Concepts

Listing, reconditioning, and inspection. All luminaires, lampholders, and retrofit kits shall be listed (410.6). Luminaires, lampholders, and retrofit kits shall not be permitted to be reconditioned; a retrofit kit installed per its instructions does not make the luminaire reconditioned (410.7). Luminaires shall be installed so that connections between luminaire conductors and circuit conductors can be inspected without disconnecting any part of the wiring, unless connected by attachment plugs and receptacles (410.8).

Specific locations (410.10). Wet-location luminaires shall be marked "Suitable for Wet Locations"; damp-location luminaires shall be marked "Suitable for Wet Locations" or "Suitable for Damp Locations" (410.10(A)). Corrosive locations require a type suitable for the location (410.10(B)).

Key Concepts

Receptacle locations and GFCI (pools, spas, fountains) - Storable pools, storable spas, storable hot tubs: receptacles shall not be located less than 1.83 m (6 ft) from the inside walls (680.34). - Permanently installed pool: at least one 125-volt, 15- or 20-ampere receptacle on a general-purpose branch circuit not less than 1.83 m (6 ft) from, and not more than 6.0 m (20 ft) from, the inside wall, and not more than 2.0 m (6 ft 6 in.) above the floor/grade (680.22(A)(1)). Other receptacles: not less than 6 ft (680.22(A)(3)); circulation/sanitation receptacles: at least 6 ft, GFCI-protected, grounding type (680.22(A)(2)). - All 15- and 20-ampere, single-phase, 125-volt receptacles within 6.0 m (20 ft) of the inside walls shall be Class A GFCI protected (680.22(A)(4)). Fountains: 15- or 20-ampere, single-phase 125-volt through 250-volt receptacles within 6.0 m (20 ft) of the fountain edge require GFCI (680.58). - Indoor spa/hot tub: a 125-volt, 15-…

Key Concepts

Personal protective equipment - The employer is responsible for requiring the wearing of appropriate PPE in all operations where there is an exposure to hazardous conditions, or where this part indicates the need for such equipment to reduce hazards to employees — §1926.28(a) (Page 31). - PPE is not the first line of defense. Per Ugly's Electrical References (Page 184), the first line of defense is turning off the power and establishing an electrically safe work condition. - Rubber insulating equipment (blankets, matting, covers, line hose, gloves, sleeves) must be marked by class (Class 00, 0, 1, 2, 3, 4) and type (Type I nonozone-resistant, Type II ozone-resistant); markings shall be nonconducting and shall not impair insulating qualities, and markings on gloves shall be confined to the cuff — §1926.97(a)(1). - Insulating equipment shall be inspected for damage before each day's use and immediately following any incident reasonably suspected of causing damage;…