Idaho Limited Electrical Elevator Installer

Idaho Limited Electrical Elevator Installer Exam — Article 90, Introduction

Key Concepts

Purpose (90.1(A)). The purpose of the Code is the practical safeguarding of persons and property from hazards arising from the use of electricity. The Code is not intended as a design specification or an instruction manual for untrained persons.

Adequacy (90.1(B)). 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 of electrical use.

International standards (90.1(C)). The requirements in the Code address the fundamental principles of protection for safety contained in Section 131 of IEC 60364-1, Electrical Installations of Buildings.

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: (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 — such as office buildings, warehouses, garages, machine shops, and recreational buildings — that are not…

Idaho Limited Electrical Elevator Installer Exam

Key Concepts

Article 100 Definitions - 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; 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 (Article 100). - Conductor, Insulated — a conductor encased within material of composition and thickness recognized by the 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 (Article 100). - Bonding Jumper, System — that same type of connection at a separately derived system (Article 100). - Bonding Conductor or Jumper — a reliable conductor to ensure the required electrical conductivity between metal parts required to be electrically connected (Article 100). - In Sight From…

Idaho Limited Electrical Elevator Installer Exam — 10 questions, 17% of exam

Key Concepts

Grounding and bonding (Article 250) - The earth shall not be considered an effective ground-fault current path — 250.4(A)(5). - Rod electrodes of stainless steel or zinc-coated steel must be at least 15.87 mm (5/8 in.) in diameter unless listed; pipe or conduit electrodes must be not smaller than trade size 3/4 — 250.52(A)(5)(b) and (a). - Concrete-encased electrode rebar: not less than 13 mm (1/2 in.) diameter, in a continuous 6.0 m (20 ft) length — 250.52(A)(3). - A single rod, pipe, or plate electrode must be supplemented unless its resistance to earth is 25 ohms or less — 250.53(A)(2) Exception. Multiple rods: not less than 1.8 m (6 ft) apart — 250.53(A)(3). - Ground ring: not less than 750 mm (30 in.) below the surface — 250.53(F); plate electrodes, same 30 in. — 250.53(H). - Rock bottom: drive at an oblique angle not to exceed 45 degrees from vertical, or bury in a trench at least 750 mm (30 in.) deep — 250.53(G). - Aluminum/copper-clad aluminum GEC used outside shall not be terminated within 450 mm (18 in.) of the earth — 250.64(A);…

Key Concepts

Conductors in parallel (310.10(H)) - Parallel connection is permitted only in sizes 1/0 AWG and larger — 310.10(H)(1). - Exception No. 1: smaller than 1/0 AWG permitted for control power to indicating instruments, contactors, relays, solenoids, or for frequencies of 360 Hz and higher, if in the same raceway or cable and the ampacity/overcurrent conditions are met. - Exception No. 2: 2 AWG and 1 AWG grounded neutrals in existing installations under engineering supervision. - Paralleled conductors must be the same length, same conductor material, same circular mil area, same insulation type, and terminated in the same manner — 310.10(H)(2). They are not required to share one raceway; 310.10(H)(3) permits separate cables or raceways. - Sectioned EGCs smaller than 1/0 AWG are allowed in multiconductor cables if the combined circular mil area in each cable complies with 250.122 — 310.10(H)(5).

Insulation types and locations - Wet-location types per 310.10(C): MTW, RHW, RHW-2, TW, THW, THW-2, THHW, THWN, THWN-2, XHHW, XHHW-2, ZW (or moisture-impervious metal-sheathed or listed for wet locations). THHN is dry and damp only — 310.10(B). - Above 2000 volts, solid dielectric conductors in permanent installations (other than industrial establishments) need ozone-resistant insulation and shielding —…

Key Concepts

Conductor sizing (Part II, Article 430) - Conductors supplying a single motor in a continuous duty application: ampacity not less than 125 percent of the motor full-load current (FLC) determined by 430.6(A)(1) — 430.22. - 430.6(A)(1): use the values in Tables 430.247–430.250 for conductor ampacity, switch ratings and branch-circuit short-circuit/ground-fault (SC/GF) protection, instead of the nameplate current. Separate overload protection is based on the nameplate current — 430.6(A)(2). - 430.22(A): dc motor from a rectified single-phase supply — conductors between rectifier output and motor: 190 percent (half-wave bridge), 150 percent (full-wave bridge). Rectifier input conductors: 125 percent of rated input current. - 430.22(B) multispeed: line side of controller based on the highest nameplate FLC; controller-to-motor not less than 125 percent of the winding(s) energized. - 430.22(C) wye-start, delta-run: line side 125 percent; controller-to-motor not less than 72 percent (58 percent × 1.25). - 430.22(D) part-winding: line side 125 percent; controller-to-motor not less than 62.5 percent (50 percent × 1.25). - 430.22(G)(2)(1): 16 AWG copper permitted where FLC is greater than 5.5 A and ≤ 8 A, with 430.52 protection, maximum Class 10 or 10A overload protection, and 240.4(D)(2)(2) overcurrent protection. - 430.24: feeders — 125 percent of…

Key Concepts

Voltage limitations (620.3) - General rule: supply voltage shall not exceed 300 volts between conductors unless permitted by 620.3(A)–(C). - 620.3(A) Power circuits: branch circuits to door operator controllers and door motors, and branch circuits/feeders to motor controllers, driving machine motors, machine brakes, and motor-generator sets shall not exceed 1000 volts. Internal/interconnecting voltages of power conversion equipment may be higher if listed for the higher voltage. Where the voltage exceeds 600 volts, "DANGER — HIGH VOLTAGE" labels complying with 110.21(B) must be attached and plainly visible. - 620.3(B) Lighting circuits: comply with Article 410. - 620.3(C) Heating and air-conditioning circuits on the car: shall not exceed 1000 volts.

Conductor insulation and size (620.11, 620.12) - 620.11(A): conductors from the hoistway riser to hoistway door interlocks must be flame retardant and suitable for not less than 200°C (392°F) — Type SF or equivalent — or physically protected by an approved method to the same rating. - 620.11(B): traveling cables must be elevator cable types listed in Table 400.4 or other approved types. - 620.11(C): permitted types are MTW, TF, TFF, TFN, TFFN, THHN, THW, THWN, TW, XHHW, hoistway cable, or other insulation designated flame retardant. Shielded conductors permitted…

Key Concepts

• Use the table values, not the nameplate. For general motor applications, NEC 430.6(A)(1) requires that the values given in Tables 430.247 through 430.250 be used to determine the ampacity of conductors, ratings of switches, and branch-circuit short-circuit and ground-fault protection — instead of the actual current rating marked on the motor nameplate (NEC 2017, 430.6(A)(1); Handbook p. 496).
• Highest/smallest rated motor. In determining compliance with 430.24, 430.53(B), and 430.53(C), the highest rated or smallest rated motor is based on the rated full-load current selected from Table 430.247, Table 430.248, Table 430.249, and Table 430.250 (430.17).
• Single continuous-duty motor conductors. Conductors supplying a single motor in a continuous duty application shall have an ampacity not less than 125 percent of the motor full-load current rating as determined by 430.6(A)(1), or not less than specified in 430.22(A) through (G).
• Branch-circuit short-circuit and ground-fault protection. Maximum ratings/settings come from Table 430.52, expressed as a percentage of full-load current (430.52).
• Disconnecting means. For motor circuits rated 1000 volts or less, the disconnecting means shall have an ampere rating not less than 115 percent of the motor full-load current rating; the exception permits a listed unfused motor-circuit…