Idaho Limited Electrical Irrigation Sprinkler Installer

Key Concepts

Purpose (90.1). 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 [90.1(A)]. Compliance plus proper maintenance results in an installation essentially free from hazard, but not necessarily efficient, convenient, or adequate for good service or future expansion [90.1(B)].

Relation to international standards (90.1(C)). The Code's requirements address the fundamental principles of protection for safety contained in Section 131 of IEC Standard 60364-1, Electrical Installations of Buildings. (IEEE/ASTM SI 10-1997 is cited in 90.9 for SI conversions — a different subject.)

Scope — covered (90.2(A)). The Code covers the installation and removal of electrical conductors, equipment, and raceways; signaling and communications conductors, equipment, and raceways; and optical fiber cables and raceways for: public and private premises, including buildings, structures, mobile homes, recreational vehicles, and floating buildings; yards, lots, parking lots, carnivals, and industrial substations; installations of conductors and equipment that connect to the supply of electricity; and installations used by the electric utility that are not an integral part of a generating plant, substation, or control center. (NEC 2017, Page 2, Article 90.2(A); NEC 2026 lists this as 90.2(A)(1).)

Scope — not covered (90.2(B)). Ships and watercraft other than floating buildings, railway rolling stock, aircraft, and automotive vehicles other than mobile homes and recreational vehicles; underground mine installations and self-propelled mobile surface mining machinery; certain railway power and signaling installations; communications equipment under the exclusive control of communications utilities; and installations under the exclusive control of an electric utility as described in 90.2(B)(5).

Topic: 2017 National Electrical Code, NFPA – Chapter 1 (Articles 100 and 110)

Key Concepts

Article 100 — Definitions (Part I applies throughout the Code)

• 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 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 means acceptable to the authority having jurisdiction. (Article 100)
• Conductor, Insulated: a conductor encased within material of composition and thickness that is recognized by this Code as electrical insulation. A covered conductor is encased in material not recognized as electrical insulation. (Article 100)
• Bonding Jumper, Main: the connection between the grounded circuit conductor and the equipment grounding conductor at the service. A system bonding jumper performs the same function at a separately derived system. (Article 100)
• Feeder: all circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device. (Article 100)
• In Sight From (Within Sight): the specified equipment must be visible AND not more than 15 m (50 ft) distant. (Article 100)
• Overcurrent Protective Device, Branch-Circuit: provided with an interrupting rating appropriate for the intended use but no less than 5000 amperes. (Article 100)
• **Copper-Clad Aluminum…

Key Concepts

Grounding and bonding (Article 250) - The earth shall not be considered an effective ground-fault current path — 250.4(A)(5). Bonding of non–current-carrying metal parts connects them together and to the electrical supply source to establish an effective ground-fault current path — 250.4(A)(3). - Electrode specifications: rod-type electrodes of stainless steel or copper/zinc-coated steel must be at least 5/8 in. diameter unless listed — 250.52(A)(5)(b); pipe or conduit electrodes not smaller than trade size 3/4 — 250.52(A)(5)(a); concrete-encased electrode = at least 20 ft of bare copper not smaller than 4 AWG, encased by at least 2 in. of concrete — 250.52(A)(3); ground ring = at least 20 ft of bare copper not smaller than 2 AWG encircling the building — 250.52(A)(4); each plate electrode exposes not less than 2 ft² (0.186 m²) to exterior soil — 250.52(A)(7). - Installation: a rod must be driven at least 8 ft; where rock bottom is encountered, drive at an oblique angle not exceeding 45° or bury in a trench at least 30 in. deep — 250.53(G). Ground ring: not less than 30 in. below the surface — 250.53(F). Multiple rod/pipe/plate electrodes: not less than 6 ft apart — 250.53(A)(3). A supplemental electrode is not required if a single rod, pipe, or plate has resistance to earth of 25 ohms or less — 250.53(A)(2) Exception. - Grounding electrode conductor: aluminum/copper-clad aluminum used outside shall not be terminated within 18 in. of the earth — 250.64(A). 6 AWG or larger copper not exposed to physical damage may run along the surface without metal protection — 250.64(B)(1). Size per Table 250.66, except it is not required to be larger than 6 AWG copper…

Key Concepts

Bends in one run. There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes. This same wording appears for RMC (344.26), IMC (342.26), PVC (352.26), LFMC (350.26), and EMT (358.26).

Raceway size limits. RMC larger than metric designator 155 (trade size 6) shall not be used (344.20(B)); RMC smaller than trade size ½ shall not be used (344.20(A)). IMC maximum is metric designator 103 (trade size 4) (342.20(B)). PVC: minimum trade size ½, maximum trade size 6 (352.20). EMT maximum is trade size 4 (358.20(B)). LFMC maximum is trade size 4 (350.20(B)).

Securing and supporting. - EMT: securely fastened at intervals not to exceed 3 m (10 ft), and each run securely fastened within 900 mm (3 ft) of each outlet box, junction box, device box, cabinet, conduit body, or other tubing termination (358.30(A)). - RMC/IMC: secured within 900 mm (3 ft) of each termination; supported at intervals not exceeding 3 m (10 ft), or per Table 344.30(B)(2) for straight runs made up with threaded couplings — trade size 1 (metric designator 27) is permitted up to 12 ft between supports (344.30, 342.30(B)(2)). - PVC: securely fastened within 900 mm (3 ft) of each termination (352.30(A)); supported per Table 352.30 — trade sizes ½–1 at 3 ft, 1¼–2 at 5 ft, 2½–3 at 6 ft, 3½–5 at 7 ft, trade size 6 at 8 ft. - LFMC: securely fastened by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other conduit termination, and supported and secured at intervals not to exceed 1.4 m (4½ ft) (350.30(A)).

Key Concepts

Scope and definitions (675.1, 675.2). Article 675 applies to electrically driven or controlled irrigation machines and to the branch circuits and controllers for such equipment. A Center Pivot Irrigation Machine is a multimotored irrigation machine that revolves around a central pivot and employs alignment switches or similar devices to control individual motors (675.2). Collector rings are an assembly of slip rings for transferring electric energy from a stationary to a rotating member.

Irrigation cable construction (675.4(A)). An assembly of stranded, insulated conductors with nonhygroscopic and nonwicking filler in a core of moisture- and flame-resistant nonmetallic material, overlaid with a metallic covering, jacketed with moisture-, corrosion-, and sunlight-resistant nonmetallic material. Conductor insulation must be a type listed in Table 310.104(A) for 75°C (167°F) and for wet locations. A composite of power, control, and grounding conductors is permitted.

Cable supports and fittings (675.4(C), (D)). Secured by straps, hangers, or similar fittings identified for the purpose, installed so as not to damage the cable, and supported at intervals not exceeding 1.2 m (4 ft). Fittings are required at all points where irrigation cable terminates.

Conductor counting (675.5). Signal and control conductors in a raceway or cable shall not be counted for ampacity adjustment under 310.15(B)(3)(a).

Main control panel nameplate (675.6). Must give: (1) manufacturer's name, rated voltage, phase, and frequency; (2) current rating of the machine; (3) rating of the main disconnecting means and size of overcurrent protection required.