ME Electrician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

NEC Article 100

The definitions article of NFPA 70. It establishes terms such as branch circuit, feeder, service, GFCI, and qualified person that govern how other articles are applied.

Authority having jurisdiction

The organization or individual responsible for approving equipment, materials, and installations under NEC 90.4. In Maine this is typically the municipal or state electrical inspector.

Maine Chapter 120

Board rule 02-031 CMR Chapter 120 adopts the National Electrical Code by reference with Maine amendments. Candidates must confirm the adopted edition before citing any section.

Table 310.16 ampacity

Lists allowable ampacities for conductors rated 0-2000 volts with not more than three current-carrying conductors in a raceway or cable at 30 degrees C ambient, before adjustment or correction.

Standard overcurrent device sizes

NEC 240.6 lists standard ratings including 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600, 700, 800, 1000, and 1200 amperes.

Box fill calculation

Under NEC 314.16 each 14 AWG conductor counts 2.00 cubic inches, 12 AWG 2.25, and 10 AWG 2.50. Each device counts as two of the largest conductor in the box.

Working clearance Table 110.26

Requires 3 ft clearance for 0-150 volts to ground, 3.5 ft for 151-300 volts, and 4 ft for 301-600 volts at conditions 1 and 2, plus 30-inch width and 6.5-foot headroom.

Dwelling receptacle spacing

NEC 210.52 requires wall-space receptacles so no point along the floor line is more than 6 feet from an outlet. Kitchen countertop receptacles must be within 24 inches of any point.

Maine Electricians' Examining Board

The licensing body within Maine's Department of Professional and Financial Regulation that administers electrician licenses, examinations, continuing education, and discipline under 32 MRSA Chapter 17.

Master Electrician license

Maine license authorizing the holder to perform and supervise all electrical work and to employ or supervise journeymen and helpers, after documenting qualifying experience and passing the master examination.

Journeyman Electrician license

Maine license authorizing electrical work under a master's supervision. The journeyman may not independently contract for electrical work or supervise a master-level scope.

Helper license

Maine license category for entry-level electrical workers performing work under direct supervision while accumulating the experience required for journeyman or master licensure.

Continuing education requirement

Maine electrician licenses renew on a fixed cycle and require Board-approved continuing education hours. Missing the deadline can lapse the license and trigger late fees.

Unlicensed electrical work

Performing electrical work without a valid Maine license is a violation subject to Board investigation, fines, and license discipline. Licenses are not transferable between individuals.

Permit and inspection

Most electrical installations in Maine require a permit and inspection by the municipal or state electrical inspector. The licensed electrician of record is responsible for the permitted work.

Scope of license

Working outside the license class, such as a journeyman contracting directly with a homeowner, is grounds for Board discipline even if the work itself is technically compliant.

Ohm's law and power

E equals I times R. Power equals E times I, also I squared times R or E squared divided by R. Single-phase watts equal volts times amperes times power factor.

Three-phase power formula

Three-phase power equals 1.732 times line voltage times line current times power factor. Line-to-line voltage equals 1.732 times line-to-neutral voltage.

Voltage drop formula

Single-phase VD equals 2KIL divided by circular mils; three-phase uses 1.732 instead of 2. K is about 12.9 for copper and 21.2 for aluminum.

NM-B cable restrictions

Nonmetallic sheathed cable is permitted in dwellings and dry interior locations but not in wet locations, where exposed to physical damage, or in most commercial occupancies.

Raceway fill limits

NEC Chapter 9 Table 1 limits conduit fill, typically 40 percent of interior cross-section for three or more conductors. Annex C gives conductor counts for common raceway types.

Securing and supporting

NM cable must be secured within 12 inches of boxes and every 4.5 feet. EMT must be supported at least every 10 feet and within 3 feet of boxes.

Motor branch circuit protection

NEC 430 requires overload protection based on nameplate current, short-circuit protection per Table 430.52, and conductors sized at 125 percent of motor full-load current.

Aluminum conductor resistance

Aluminum has roughly 1.6 times the resistance of copper for the same circular-mil area, so terminations require listed connectors and antioxidant compound to prevent failure.

Grounding versus bonding

Grounding connects the electrical system to earth. Bonding connects metal parts together to create a low-impedance fault path back to the source for overcurrent device operation.

Grounding electrode system

NEC 250.50 requires a grounding electrode system at each service, using ground rods, metal water pipe with 10 feet or more in earth, concrete-encased electrode, or ground ring.

25-ohm ground rod rule

A single ground rod must measure 25 ohms or less to earth or be supplemented by one additional electrode at least 6 feet away, per NEC 250.53(A)(2).

Equipment grounding conductor sizing

Table 250.122 sizes the equipment grounding conductor based on the rating of the overcurrent device protecting the circuit, not the ampacity of the circuit conductors.

Main bonding jumper

The connection between the grounded conductor and equipment grounding bus exists only at the service. Installing it at a subpanel creates parallel neutral paths and is prohibited.

Next-size-up rule

NEC 240.4(B) permits the next standard overcurrent device rating above conductor ampacity only where the ampacity does not exceed 800 amperes and the next size does not exceed 800 amperes.

GFCI and AFCI protection

NEC 210.8 requires GFCI protection in dwelling bathrooms, kitchens, garages, outdoors, and similar locations. NEC 210.12 requires AFCI protection on most dwelling 120-volt branch circuits.

NFPA 70E approach boundaries

NFPA 70E sets limited and restricted shock approach boundaries and requires a risk assessment, appropriate PPE, and lockout/tagout before work on energized equipment.