Mississippi - NASCLA ACCREDITED TRADE EXAMINATION FOR ELECTRICAL CONTRACTORS

Key Concepts

Bidding and estimating (NASCLA Contractors Guide, Bidding and Estimating chapter) - A bidder can be found "unresponsive" if information in the bid package is incorrectly submitted or omitted altogether (Page 7-1, Bid Documents). - Bid peddling: the subcontractor approaches the general contractor after the award, intending to lower the price submitted on bid day (Page 7-2). Bid shopping: the general contractor approaches subcontractors other than those who bid, seeking a lower offer (Bid Shopping section). - Bid review by the owner is generally a 30- to 90-day process (Submitting Your Bid section). - A good estimate falls within 1 percent to 2 percent of actual construction costs (Estimate Planning section). - Quantity take-off adds subcontractor fees, labor burden, project overhead, project equipment, contingencies, allowances, company overhead, and profit. Equipment salvage value is not part of estimating (Quantity Take-off section). - The unit price method bundles labor, materials, equipment, and subcontractors into a…

Key Concepts

Energized electrical work permits (NFPA 70E 130.2). A permit is required when work is performed within the restricted approach boundary, or when the employee interacts with equipment where conductors are not exposed but an increased likelihood of injury from arc flash exists [130.2(A)]. Exempt work — if a qualified person uses appropriate safe work practices and PPE — includes testing, troubleshooting, and voltage measuring; thermography, ultrasound, or visual inspection if the restricted approach boundary is not crossed; access/egress; and housekeeping [130.2(C)]. On the sample permit in Informative Annex J, Figure J.1, Part I is completed by the requester (circuit/equipment description and location, work to be done, justification for not de-energizing); risk-assessment results, safe work practices, and access-restriction means are Part II items for the electrically qualified persons.

Key Concepts

• Ohm's Law relates intensity (I, amperes), electromotive force (E, volts) and resistance (R, ohms): I = E/R, E = I × R, R = E/I (Theory 12.6(B) and 12.7; Ugly's 2023, Ohm's Law, p. 1). Current is directly proportional to voltage (12.6(A)(1)) and inversely proportional to resistance (12.6(A)(2)).
• Utilization voltages: residential lights and receptacles 120V, large loads 120/240V or 240V (12.3(A)(1)); in commercial and industrial occupancies, 277V for lighting and 480V for motors, air-conditioning and similar equipment (12.3(A)(2)).
• Meters: voltmeters connect in parallel with the load (12.3(B)); series-connected ammeters connect in series and handheld units are typically limited to a maximum of 10 amperes (12.5(B)(1)); clamp-on ammeters read without opening the circuit and can measure into the thousands of amperes (12.5(B)(2)); ohmmeters read resistance in ohms (12.4(B)).
• Series circuits (Ugly's, Series Circuits, p. 3): Rule 1 — IT = I1 = I2 = I3; Rule 2 — `ET…

Key Concepts

Code arrangement (Article 90). Chapters 1, 2, 3, and 4 apply generally. Chapters 5, 6, and 7 apply to special occupancies, special equipment, or other special conditions and may supplement or modify the requirements in Chapters 1 through 7. Chapter 8 covers communications systems and is not subject to Chapters 1 through 7 except where specifically referenced in Chapter 8; Chapter 9 consists of tables applicable as referenced (90.3). Limiting the number of circuits in a single enclosure minimizes the effects from a short circuit or ground fault (90.8(B)). SI units appear first with inch-pound units immediately following in parentheses, and conversion from inch-pound to SI is based on hard conversion except as provided in 90.9(C); by exception, tables in Informative Annex C may list trade sizes before SI units (90.9(B)).

Key Concepts

Feeders and branch circuits - Feeder conductors supplying continuous loads must have ampacity not less than the noncontinuous load plus 125 percent of the continuous load — NEC 2023, 215.2(A)(1). The feeder overcurrent device rating is likewise not less than noncontinuous plus 125 percent of continuous — 215.3. - Branch-circuit OCPD rating shall be not less than 125 percent of the continuous load — 210.20(A). - Up to three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders may use a common neutral — 215.4(A). - Voltage drop: 3 percent at the farthest outlet for branch circuits, with total on feeders plus branch circuits not exceeding 5 percent — 210.19, Informational Note (same guidance for feeders in 215.2(A)(2), Informational Note No. 2). - Feeder SPD required where a feeder supplies dwelling units, dormitory units, hotel/motel guest rooms and suites, or nursing-home patient sleeping rooms; Type 1 or Type 2,…

Key Concepts

Physical protection in framing (300.4). Bored holes must have the edge not less than 32 mm (1 1/4 in.) from the edge of the wood member; where that cannot be maintained, protect with a steel plate at least 1.6 mm (1/16 in.) thick [300.4(A)(1)]. Cables in notches get the same 1.6 mm (1/16 in.) plate [300.4(A)(2)]. Cables/raceways run parallel to framing members or furring strips must keep the nearest outside surface not less than 32 mm (1 1/4 in.) from the edge, or be protected by a 1.6 mm (1/16 in.) plate or sleeve; RMC, IMC, rigid nonmetallic conduit, and EMT are excepted [300.4(D)]. Under metal-corrugated sheet roof decking, keep not less than 38 mm (1 1/2 in.) from the lowest surface of the decking to the top of the cable, raceway, or box [300.4(E)].

Key Concepts

Motor conductor sizing (Art. 430, Part II) - Conductors supplying a single continuous-duty motor: ampacity not less than 125 percent of motor full-load current per 430.6(A)(1) — NEC 2023, 430.22. - Wye-start, delta-run: line-side conductors not less than 125 percent; conductors between controller and motor not less than 72 percent of FLC (58% × 1.25) — 430.22(C). Part-winding: 62.5 percent between controller and motor — 430.22(D). - DC motor from rectified single-phase supply: 190 percent for a half-wave bridge, 150 percent for a full-wave bridge — 430.22(A). - Other-than-continuous duty: use Table 430.22(E); intermittent duty, 30- and 60-minute rated motor = 90 percent of nameplate current. - 18 AWG copper is permitted for a motor with FLC greater than 3.5 A and ≤ 5 A only with maximum Class 10 or Class 10A overload protection per 430.32 (Class 20 for FLC ≤ 3.5 A) — 430.22(G)(1). - Several motors: **125 percent of…

Key Concepts

Hazardous (classified) location basics - Class I, Division 1 is a location in which ignitible concentrations of flammable gases or vapors can exist under normal operating conditions (500.5(B)(1)). - Group D covers flammable gas/vapor having a maximum experimental safe gap (MESG) greater than 0.75 mm or a minimum igniting current (MIC) ratio greater than 0.80 (500.6(A)(4)). - Class I, Division 1 conduit seals entering an explosionproof enclosure: installed within 450 mm (18 in.) of the enclosure, or as required by the enclosure marking. Only threaded couplings or explosionproof fittings (unions, reducers, elbows, capped elbows) not larger than the conduit trade size are permitted between the seal and the enclosure (501.15(A)(1)). - Completed seals other than listed cable sealing fittings: compound thickness not less than the trade size of the fitting, and in no case less than 16 mm (5/8 in.) (501.15(C)(3)). Compound melting point not less than 93°C (200°F) (501.15(C)(2)). - Division…

Mississippi NASCLA Accredited Trade Examination for Electrical Contractors (1 question, 1% of exam)

Key Concepts

Primary protection (805.90(A)). A listed primary protector is required on each circuit run partly or entirely in aerial wire or aerial cable not confined within a block. A listed primary protector is also required on each circuit, aerial or underground, located within the block containing the building served so as to be exposed to accidental contact with electric light or power conductors operating at over 300 volts to ground. Where lightning exposure exists, each interbuilding circuit must be protected by a listed primary protector at each end. Location: in, on, or immediately adjacent to the structure served and as close as practicable to the point of entrance (805.90(B)); not in hazardous (classified) locations (805.90(C)). Article 840 systems: "The requirements of 805.90 shall apply" (840.90).