MA Electrician flashcards

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

NEC Article 90 scope

Article 90 states the NEC covers electrical installations, including conductors, equipment, and optically powered systems, but excludes utility-owned installations and certain other systems.

Approved equipment

Approved means acceptable to the authority having jurisdiction; listing by a recognized testing laboratory is common evidence, and labeled equipment must be installed per instructions.

Working clearance height

The dedicated electrical working space must be at least 6.5 feet high, 30 inches wide, and extend from the floor or platform to the structural ceiling.

Shall versus should

In the NEC, 'shall' indicates a mandatory requirement, 'shall not' a prohibition, and 'should' a recommendation or advisory practice rather than an enforceable rule.

NM cable support

Nonmetallic-sheathed cable must be secured every 4.5 feet and within 12 inches of each box, unless specifically permitted otherwise by the Code.

Conduit fill percentages

Chapter 9 Table 1 permits 53 percent fill for one conductor, 31 percent for two conductors, and 40 percent for three or more conductors in a raceway.

Box fill counting

Box fill counts each conductor, each clamp, each device, and each equipment grounding conductor using Article 314.16 volume allowances before comparing with the box volume.

Parallel conductor rules

Parallel conductors must be 1/0 AWG or larger, identical in material, size, insulation, and length, and terminated so current divides equally.

Continuous load factor

For branch circuits, feeders, and services, continuous loads are calculated at 125 percent of their ampere rating, then added to noncontinuous loads.

Kitchen small appliance circuits

A dwelling kitchen must have at least two 20-ampere small-appliance branch circuits for countertop receptacles, and these circuits may not supply other outlets.

Receptacle wall spacing

In dwelling units, receptacle outlets along walls must be spaced so no point on the wall is more than 6 feet from a receptacle.

Voltage drop recommendation

NEC informational notes recommend no more than 3 percent voltage drop on a branch circuit and no more than 5 percent total from service to load.

Equipment grounding conductor

The equipment grounding conductor provides a low-impedance path for fault current back to the source, allowing overcurrent protection to operate quickly.

Ground rod supplement

A single ground rod must have 25 ohms or less resistance; if not, a supplemental electrode is required, unless the single rod meets the value.

Small conductor protection

Unless specifically permitted, 14 AWG copper is protected at 15 amperes, 12 AWG at 20 amperes, and 10 AWG at 30 amperes.

GFCI protection

Ground-fault circuit-interrupter protection is required for receptacles in bathrooms, kitchens, outdoors, garages, unfinished basements, and other specified wet or hazardous areas.

Ohm's law

Ohm's law states that voltage equals current times resistance, V = I × R, and can be rearranged to find current or resistance.

Three-phase power

For a balanced three-phase circuit, power in kilowatts equals the square root of three times line voltage times line current times power factor, divided by 1000.

Power factor

Power factor is true power divided by apparent power, P/S; it equals the cosine of the angle between voltage and current in a sinusoidal circuit.

Wye line voltage

In a balanced wye connection, line voltage equals the square root of three times phase voltage, while line current equals phase current.

Motor branch conductors

Motor branch-circuit conductors are sized at 125 percent of the motor full-load current from the Code tables, not the motor nameplate current.

Motor disconnect location

A motor disconnecting means must be within sight of the motor and controller, or capable of being locked open, as permitted by Article 430.

Motor overload protection

Motor overload protection guards the motor against excessive current from overloads; it is sized from the motor nameplate current and is separate from short-circuit protection.

HVAC disconnect

For air-conditioning and refrigeration equipment, a disconnecting means must be within sight and readily accessible from the equipment, as required by Article 440.

Class I location

A Class I hazardous location contains or may contain flammable gases or vapors in quantities sufficient to produce explosive or ignitable mixtures.

Pool equipotential bonding

Swimming pool bonding connects metal parts, equipment, and pool water to a common equipotential grid to reduce voltage differences and shock risk.

Rapid shutdown

Photovoltaic systems on buildings require rapid shutdown so conductors within the array and outside the array are reduced to a safe voltage for firefighters.

Massachusetts Electrical Code

The Massachusetts Electrical Code is 527 CMR 12.00, which adopts the National Electrical Code with Massachusetts amendments and is enforced by local wiring inspectors.

Master electrician role

A Massachusetts master electrician is licensed to perform electrical work and obtain electrical permits; journeyman electricians work under a master's supervision.

Local wiring inspector

The local wiring inspector enforces the Massachusetts Electrical Code in the municipality, issues permits, and inspects electrical installations for compliance.

Limited approach boundary

The limited approach boundary is the distance from exposed energized parts that unqualified persons must not cross; only qualified persons with proper protection may enter.

Lockout tagout

Lockout/tagout isolates energy sources with locks and tags, and the qualified worker verifies absence of voltage before beginning work on equipment.