Idaho Limited Electrical Limited Energy Installer

Key Concepts

90.1 Purpose - (A) The purpose of the Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. It is not intended as a design specification or an instruction manual for untrained persons. - (B) Compliance plus proper maintenance results in an installation that is "essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use." - Informational Note to 90.1(B): Hazards often occur because of overloading of wiring systems by methods or usage not in conformity with the Code — this occurs because initial wiring did not provide for increases in the use of electricity. - (C) The Code's requirements address the fundamental principles of protection for safety in Section 131 of IEC 60364-1, Electrical Installations of Buildings (shock, thermal effects, overcurrent, fault currents, overvoltage).

90.2 Scope - (A) Covered: the installation and removal of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways — for (1) public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings; (2) yards, lots, parking lots, carnivals, and industrial substations; (3) installations of conductors and equipment that connect to the supply of electricity; (4) **installations used by the electric utility — office buildings, warehouses, garages, machine shops, recreational buildings — that are not an…

Key Concepts

Article 100 — Definitions (Part I applies throughout the Code; Part II applies to installations over 1000 volts, nominal)

• Ampacity: The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. (Article 100; NEC 2017, Page 9)
• Continuous Load: A load where the maximum current is expected to continue for 3 hours or more. (Article 100; NEC 2017, Page 8) This definition drives the 125 percent sizing rules found elsewhere in the Code.
• Authority Having Jurisdiction (AHJ): An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure. (Article 100)
• Approved: Acceptable to the authority having jurisdiction. (Article 100)
• Accessible (as applied to equipment): Admitting close approach; not guarded by locked doors, elevation, or other effective means. (Article 100)
• Accessible (as applied to wiring methods): Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building. (Article 100)
• Readily Accessible: Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to use tools (other than keys), climb over or under, remove obstacles, or resort to portable ladders. (Article 100)
• **In Sight From (Within…

Idaho Limited Electrical – Limited Energy Installer Exam

Key Concepts

Overcurrent protection (Article 240) - 14 AWG copper conductors shall have overcurrent protection not exceeding 15 amperes — 240.4(D)(3) (Handbook p. 150). - The next higher standard overcurrent device rating above conductor ampacity is permitted only if three conditions are met, including that the next higher standard rating selected does not exceed 800 amperes, and that the conductors are not part of a branch circuit supplying more than one receptacle for cord-and-plug-connected portable loads — 240.4(B) (p. 149). This provision shall not be permitted for tap conductors — 240.21(B). - Standard ampere ratings for fuses and inverse time circuit breakers are those in Table 240.6(A); additional standard ratings for fuses are 1, 3, 6, 10, and 601. Nonstandard-rated devices are permitted to be used — 240.6(A) (p. 151). - Ground-fault protection of equipment is required per 230.95 for solidly grounded wye systems of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase, for each individual device used as a building or structure main disconnecting means rated 1000 amperes or more — 240.13 (p. 152). It does not apply to continuous industrial processes where nonorderly shutdown adds hazards, installations with GF protection provided by other service/feeder requirements, or fire pumps. - 10 ft feeder taps: for field installations, if the tap conductors leave the enclosure or vault in which the…

Key Concepts

Article 310 — Conductor uses and construction - Wet-location insulated conductors must be moisture-impervious metal-sheathed, listed for wet locations, or Types MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, or ZW [310.10(C)]. THHN, RHH and SA are recognized for dry and damp locations only [310.10(B)]. - For other than industrial establishments, solid dielectric insulated conductors operated above 2000 volts in permanent installations must have ozone-resistant insulation and be shielded, with metallic shields connected to a grounding electrode conductor, grounding busbar, equipment grounding conductor, or grounding electrode [310.10(E)]. - Direct-burial cables rated above 2000 volts must be shielded; Exception No. 1 permits nonshielded multiconductor cables rated 2001–2400 V with an overall metallic sheath or armor [310.10(F)]. - Parallel conductors are permitted only in sizes 1/0 AWG and larger [310.10(H)(1)]. Exception No. 2 permits 2 AWG and 1 AWG grounded neutral conductors in parallel for existing installations under engineering supervision. Paralleled conductors of each phase must match in length, material, circular mil area, insulation type and termination method [310.10(H)(2)]; conductors of one phase are not required to have the same physical characteristics as another phase [310.10(H)(3)]. - Conductors 8 AWG and larger in raceways must be stranded unless the Code permits or requires solid [310.106(C)]. Solid aluminum 8, 10 and 12 AWG must be AA-8000 series alloy [310.106(B)]. - Required markings: maximum rated voltage, type letter(s), manufacturer identification, AWG/circular…

Key Concepts

Article 720 — Less than 50 volts - Conductors shall not be smaller than 12 AWG copper or equivalent; appliance branch circuits supplying more than one appliance or appliance receptacle not smaller than 10 AWG (720.4). - Standard lampholders shall have a rating of not less than 660 watts (720.5); receptacles not less than 15 amperes (720.6); receptacles of not less than 20-ampere rating in kitchens, laundries, and similar locations (720.7).

Article 725 — Class 1, 2, 3 - Class 1 power-limited: source rated output not more than 30 volts and 1000 volt-amperes (725.41(A)). Non-transformer sources: overcurrent device rated not more than 167 percent of the VA rating divided by rated voltage; VA max limited to 2500 VA; I max × V max not to exceed 10,000 VA (725.41(A)(2)). - Class 1 remote-control and signaling circuits shall not exceed 600 volts; source output need not be limited (725.41(B)). - Overcurrent protection shall not exceed 7 amperes for 18 AWG and 10 amperes for 16 AWG; 14 AWG and larger per conductor ampacity without applying the adjustment and correction factors of 310.15 (725.43). Branch-circuit taps 14 AWG and larger: device rating not more than 300 percent of the Class 1 conductor ampacity (725.45(C)). - 18 AWG and 16 AWG permitted (725.49(A)); insulation rated for system voltage and not less than 600 volts (725.49(B)). - Class 1 with power-supply circuits in the…

Key Concepts

Scope and structure (220.1). Article 220 provides requirements for calculating branch-circuit, feeder, and service loads. Part I = general; Part II = branch-circuit load calculations; Parts III and IV = feeder and service load calculations; Part V = farm loads.

General lighting load (220.12). A unit load of not less than that specified in Table 220.12 constitutes the minimum lighting load. Floor area for each floor is calculated from the outside dimensions of the building, dwelling unit, or other area. For dwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinished spaces not adaptable for future use.

Receptacle outlets (220.14(I)). Except as covered in 220.14(J) and (K), receptacle outlets are calculated at not less than 180 volt-amperes for each single or for each multiple receptacle on one yoke. A single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles is calculated at not less than 90 volt-amperes per receptacle.

Dwelling occupancies (220.14(J)). In one-, two-, and multifamily dwellings and in guest rooms/suites of hotels and motels, general-use receptacle outlets of 20-ampere rating or less, the outlets of 210.52(E) and (G), and lighting outlets of 210.70(A) and (B) are included in the general lighting load of 220.12 — no additional load calculation required.