Idaho Limited Electrical Water Pump Installer

Key Concepts

Purpose — 90.1 - 90.1(A) Practical Safeguarding: The purpose of the Code is "the practical safeguarding of persons and property from hazards arising from the use of electricity." It is not a design specification or an instruction manual for untrained persons. - 90.1(B) Adequacy: Compliance with the Code and proper maintenance result 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." - 90.1(C): Code requirements address the fundamental principles of protection for safety in Section 131 of IEC Standard 60364-1.

Scope — 90.2 (NEC 2017, Page 2) - 90.2(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 integral part of a generating plant, substation, or control center. - 90.2(B) Not Covered: ships, watercraft other than floating buildings, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and recreational vehicles; installations underground in mines and self-propelled mobile surface mining machinery…

Key Concepts

Article 100, Part I — Definitions (definitions in Part I apply wherever the terms are used 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, Page 9)
• Continuous Load — a load where the maximum current is expected to continue for 3 hours or more. (Article 100, Page 8)
• 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. Approved means acceptable to the authority having jurisdiction. (Article 100)
• In Sight From (Within Sight From, Within Sight) — the specified equipment must be visible and not more than 15 m (50 ft) distant from the other equipment. (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 Conductors — copper metallurgically bonded to an aluminum core, forming a minimum of 10 percent of the cross-sectional area of a solid conductor or of each strand of a stranded conductor. (Article 100)
• GFCI — informational note: Class A devices trip when current to ground is 6 mA or higher and…

Key Concepts

Grounding fundamentals (Art. 250, Part I) - Bonding of equipment on a grounded system connects non–current-carrying conductive materials together and to the electrical supply source in a manner that establishes an effective ground-fault current path [250.4(A)(3)]. - The earth shall not be considered an effective ground-fault current path [250.4(A)(5)]. - Currents that introduce noise or data errors in electronic equipment shall NOT be considered the objectionable currents addressed in 250.6 [250.6(D)].

Grounding electrodes (250.52) - Metal underground water pipe: in direct contact with earth for 10 ft (3.0 m) or more and electrically continuous [250.52(A)(1)]. - Concrete-encased electrode: at least 20 ft (6.0 m) of 1/2 in. or larger rebar, or 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 [250.52(A)(4)]; installed not less than 30 in. (750 mm) below the earth's surface [250.53(F)]. Plate electrodes: same 30 in. minimum [250.53(H)]. - Rod and pipe electrodes: not less than 8 ft long. Pipe/conduit not smaller than metric designator 21 (trade size 3/4) [250.52(A)(5)(a)]; rod-type stainless steel or copper/zinc-coated steel at least 5/8 in. (15.87 mm) diameter, unless listed [250.52(A)(5)(b)]. - Plate electrode: expose not less than 0.186 m² (2 ft²) of surface to exterior soil [250.52(A)(7)]. - Not permitted as electrodes: metal underground gas piping systems, aluminum, and…

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 — RMC 344.26, IMC 342.26, PVC 352.26, FMC 348.26, LFMC 350.26, EMT 358.26.

Sizes. RMC larger than metric designator 155 (trade size 6) shall not be used — 344.20(B). IMC maximum is metric designator 103 (trade size 4) — 342.20(B); EMT maximum is trade size 4 — 358.20(B); LFMC maximum trade size 4 — 350.20(B).

Securing and supporting. - EMT: securely fastened at intervals not to exceed 3 m (10 ft), and each run fastened within 900 mm (3 ft) of each box, cabinet, conduit body, or other tubing termination — 358.30(A). - RMC/IMC: fastened within 900 mm (3 ft) of each termination (5 ft where structural members do not readily permit), supported at intervals not exceeding 3 m (10 ft), or per Table 344.30(B)(2) where made up with threaded couplings — 344.30, 342.30(B)(2). - FMC and LFMC: fastened within 300 mm (12 in.) of each box, cabinet, conduit body, or other termination, supported at intervals not to exceed 1.4 m (4½ ft) — 348.30(A), 350.30(A). - PVC: fastened within 900 mm (3 ft) of each termination — 352.30(A); supported per Table 352.30.

Key Concepts

Determining current values. For general motor applications, use the values in Tables 430.247 through 430.250 to determine conductor ampacity and ampere ratings of switches and branch-circuit short-circuit and ground-fault (BCSC/GF) protection — not the nameplate current [430.6(A)(1)]. Separate motor overload protection is based on the motor nameplate current rating [430.6(A)(2)]. Table 430.247 = dc, 430.248 = single-phase ac, 430.249 = two-phase, 430.250 = three-phase.

Conductors (Part II). Conductors supplying a single motor in a continuous duty application: ampacity not less than 125 percent of motor FLC [430.22]. Special cases: - Rectifier-supplied dc: single-phase half-wave bridge, not less than 190 percent; full-wave bridge, not less than 150 percent [430.22(A)(1), (A)(2)]; rectifier input conductors 125 percent of rated input current. - Multispeed: line-side conductors based on the highest nameplate FLC; controller-to-motor conductors not less than 125 percent of the winding(s) energized [430.22(B)]. - Wye-start, delta-run: line side 125 percent; controller-to-motor not less than 72 percent (58% × 1.25) [430.22(C)]. - Part-winding: line side 125 percent; controller-to-motor not less than 62.5 percent (50% × 1.25) [430.22(D)]. - Small motors: not smaller than 14 AWG unless 430.22(G)(1) or (G)(2) applies. 18 AWG copper is permitted where FLC is greater than 3.5 A and not more than 5 A with maximum Class 10 or Class 10A overload protection; FLC of 3.5 A or less requires maximum Class 20 [430.22(G)(1)]. - Feeders: 125 percent of the…

Key Concepts

• Scope of Article 430. Article 430 covers motors, motor branch-circuit and feeder conductors and their protection, motor overload protection, motor control circuits, motor controllers, and motor control centers (430.1).
• Determining FLC — tables vs. nameplate. For general motor applications, the values in Table 430.247, Table 430.248, Table 430.249, and Table 430.250 shall be used to determine conductor ampacity and ampere ratings of switches and branch-circuit short-circuit and ground-fault protection, instead of the nameplate current rating. Exception: motors built for low speeds (less than 1200 RPM) or high torques, and multispeed motors, use the nameplate current ratings (430.6(A)(1)).
• Reduced-voltage/multi-winding conductor sizing. For a wye-start, delta-run motor, the conductors between the controller and the motor shall have an ampacity not less than 72 percent of the motor full-load current (430.22(C)). For part-winding motors the figure is 62.5 percent (430.22(D)). The 125 percent figure applies to the branch-circuit (line-side) conductors (430.22).
• Part-winding motors (430.4). Each motor-winding connection shall have branch-circuit short-circuit and ground-fault protection rated at not more than one-half that specified by 430.52. Where separate overload devices are used, each half of the winding shall be individually protected per 430.32 and 430.37 with a trip current one-half that specified. Exception: one short-circuit and ground-fault protective device is permitted for both windings if it will allow the motor to start; where time-delay (dual-element) fuses are used, they may have…