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133 Cards in this Set
- Front
- Back
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When was the first National Electrical Code Established
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1911
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Who Established the " National Electrical Code"
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National Fire Protection Agency
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What is the purpose of the NEC
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Provide Information to assure the safe installation of electrical wiring for the protection of life & property
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What is an electrical permit
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Authorize the electrican to begin the wiring installation and insure the installation will be inspected
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What does UL do?
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Underwriters Laboratory Inc. researches and test electrical wiring material
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What is the purpose of transformers in an electrical distribution system?
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To avoid excessive voltage - power loss during transportation process
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Ampere:
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Unit of measure to determine the rate of current flow
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Conductor:
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Low Impedence material; usually copper or aluminum
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Load:
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appliance, lighting, etc. controls current flow
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Overcurrent Protection Device
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Fuse or Circuit Breaker controls the flow by interupting the circuit.
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Grounding Conductor
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Fault current path so that current flow outside of the normal path can return to the source. Primary function is to allow enough current to trip breaker.
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Service Meter:
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Measures the total energy consumed in a certain period of time.
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Voltage:
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Measure of electrical preasure or electromotive force
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Wattage:
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Measure of the rate of doing electrical work, found by multiplying the voltage & current together. P=IE
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嘴
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zuǐ
Mund |
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Difference between a "hot" conductor and a grounded conductor?
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Grounding conductor transmits current to earth incase of short circuit.
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Special purpose outlet:
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Outlet that has a dedicated circuit for a specific device.
Furnace, AC unit, Dish Washer |
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GFCI:
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Ground Fault Circuit Interupter
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How to tell if a tool is truly insulated?
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Tools should have a UL stamp or insulated marking on them.
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Frame Structure : Sill Plate
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Wood Structure that sits on top of the foundation and forms frame to which floor joist are attached
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Frame Structure: Bottom Plate
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Lower part of the wall frame, attached to the top of the subfloor.
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Frame Structure: Wall Stud
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Used to form the verticle portion of the wall frame, typically 16" apart.
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Electrical Circuit
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two or more conductors thru which current flows from a power source to a load.
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Principle parts of an electrical system entrance
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Service Drop, Service Entrance, Service meter, Service Entrance panel
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In a two wire circuit: black is? white is?
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Black is the ungrounded conductor.
White is the grounded conductor |
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Physical components that make up a typical residential circuit?
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Service Entrance, Electrical Meter, Service Entrance Panel, and Sub panel
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Branch Circuit:
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Conductors between circuit breaker and the last outlet, switch or receptable on a circuit.
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Feeder Circuit:
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Circuits that run between the service entrance panel and a sub panel.
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General Purpose branch circuit
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Major portion of residential wiring systems, includes lighting, outlets and receptacles.
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Small Appliance Branch Circuit
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Supplies power to kitchen and dining area where small appliances are most common.
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Distance between receptacles on an unbroken wall?
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6ft to 12 ft.
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The term used for a one line diagram, on a blueprint?
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Circuit Layout
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Minimal conductor size for a small appliance branch circuit?
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12-2 AWG
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Individual branch circuit
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Supply current to only one appliance or piece of equipment. Dish washer, AC unit, Furnace
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What determines the conductor size for an individual branch circuit/
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Total amound of current draw or the total LOAD.
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What does the NEC require for bathroom branch circuits?
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Must be serviced by a special dedicated 20 amp GFCI protected circuit.
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Difference between a solid orange line and a dotted line on a wiring plan?
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Solid Line represents an electrical circuit; dotted line represents switches on the circuit.
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Who determines how receptacles will be tied together?
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The electrician / installer
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Guidelines for locating the service entrance panel?
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Near Service entrance close to any high powered equipment.
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Height of electrical panel above the floor?
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aproximately 40-48 inches above the floor.
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According to the NEC what is the maximum distance between receptacles?
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6-12 ft on an unbroken wall?
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According to the NEC what is the height of the receptacles?
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between 12-16 inches above the floor.
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Distance of counter top receptacles in a kitchen.
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Every 4ft of counter top.
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How to calculate required number of general purpose circuits?
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One general purpose circuit for every 500 sq ft of living space. Total sq ft divided by 500 = minimal # of circuits.
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Another name for a device box?
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Switch Box
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Difference between a device box and an outlet box?
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Outlet box: houses conductors or cable junctions:
Device box: houses switches or receptacles. |
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What wiring methods are allowed to be used with non metallic boxes?
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Typically used for receptables or switch installation. Non metallic sheath cable only.
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What is another name for romex?
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Non-Metallic Sheath Cable
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Dimensions of most non metallic box?
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2' x 3"
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How are knockouts removed from a box?
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Screw driver
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How does a depth adjusting box work?
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Adjust screw to allow box to move in or out.
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Are clamps required in metal single gang boxes?
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Yes
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What are mounting ears for?
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Make mounting or adjusting box easier
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Difference between a knockout and pryout?
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Knock out requires sometype of connector, pryout tycial with cable assembly installation.
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Maximum depth for a box in a noncombustable wall?
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No more than 1/4" back
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What determines the depth to install a box on a wood frame stud?
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depends on the finish material to be used.
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Handy Box?
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Designed to be mounted directly to a surface or a stud.
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Device Box?
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Designed to be installed in a planned finished area
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are junction boxes required to be accessable?
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yes
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How does NEC define accessable?
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Must be accessable without modifying a finished area / material to gain access.
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What is done with unused opening in a metallic box?
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Knock-out plugs must be used.
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Two methods to mount boxes in addition to nailing them directly to the frame?
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Adjustable outlet boxes, and scrap lumber
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What special requirements must be made to install a ceiling fan?
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Requires a special hanger assembly or special outlet box rated for the weight of the fan.
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Purpose of providing free air space in devices and outlet boxes?
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Assures that all components inside the box will have sufficient air circulation and keep cool.
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What is the NEC 370-16 table used for?
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determines the maximum conductor count or the minimal box size required for an application.
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What is the overal covering on a cable called?
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sheath
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what markings should be found on the outer jacket covering of a cable?
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cable type, voltage rating, number of conductors, wire awg,
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difference between a cable and conductor?
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cables are made up of multiple conductors. Conductor is an individual wire.
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why is copper consider the best conductor?
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durability and cost
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where is aluminum conductors generally used?
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service entrance and feeder cables.
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What is the largest wire size and how is it measured?
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1 AWG, measured in KCmil
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what is a circular mil?
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area of a circle with a diameter of 1/1000 of an inch.
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How does the NEC define ampacity ( test question)
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The current in amperes a conductor can carry continously under conditions of use without exceeding it's temperature rating.
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What size of wire is normally used for a general purpose branch circuit? test question
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12 or 14 AWG
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What does the letter H stand for in conductor nomenclature?
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adds 15C to a 60C conductor operating temperature
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are all grounded conductors assumed to be neutral conductors?
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NO, only special circumstances
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why are conductors colored coded?
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NEC requires all insulated conductors to be color coded, to make it quicker & safer to identify
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What is NM Cable? test question
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Non-Metallic Cable, used for general purpose
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What is SE Cable? test question
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Service Entrance Cable
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What is UF Cable? test question
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Underground Feeder Cable.
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Can NM cable be used for outdoors?
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NM can not be exposed to sunlight, but under cover it can be.
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Why avoid sharp bends when installing NM Cable?
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The inside bend radius will result increase heat which can damage the conductor
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Why must holes be drilled in center of stud?
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to no weaken the framing member
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typical drill bit size for drilling holes in wood frame construction?
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Between 5/8' and 1' bit
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Purpose of running board?
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Reduce the rist of cables damage, provides additional support for installation.
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How should NM cable be unrolled?
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Begin from the inside of the roll.
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How much cable length is required to make a connection in a box? test question
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6" to 8" of conductor
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what is teh advantage of cable staples over normal staples?
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provide additional insulated protection for the cable sheath
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How close is teh first staple to the box?
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8' for nonmetallic box, and 12" for metallic box
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How much sheatch must be inside the box?
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1/4 " is required to provide protection when used with connectors
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How much electricians tape should be applied to a split-bolt connector splice?
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Wrapped so the tape is the same thickness as the conductors insulation?
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Three type sof solderless connectors?
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wire nuts, crimp on connectors, and split bolt connectors
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what electrical markings should be on a duplex receptacle?
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maximum voltage, amperage, and conductor size, UL
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where are teh connecting tabs located on a duplex receptacle?
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located between the two halved of the receptable
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what is it called when a receptacle has its top half switched, and bottom half hot all the time? test question
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Split Switch receptacle
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Are receptacles marked al/cu permitted?
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NO
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What limitations are placed on the use of back wired receptacles?
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can only be used at the end of a series of circuits. Used to terminate the final outlet.
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Uses of a split wired receptacle
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Upper half can control a light or device, while bottom provides continuous power.
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Where are GFCI receptacles required?
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Where dampness or water is present, including garages.
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How much insulation should be stripped for connecting a conductor to a terminal?
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5/8" is typical
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Which conductor is connected to the silver terminal on a recep?
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The white or grounded conductor
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How are grounding connections made?
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grounding conductor is connected to the grounding terminals
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what is a jumper wire for?
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Small piece of wire used to connect multiple conductrs to each other and device.
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what is a multiwire circuit? test question
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a 3 conductor cable with ground installed as a 120/240 circuit?
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What does line and load mean in respect to switch terminals?
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Line: the power source connections.
Load: the output to devices |
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Single pole and double pole switch?
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Single pole typically only controls 1 circuit, while double pole controls two circuits
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Switch Leg?
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A connector that brings power from the source to the switch. Hot feed, Hot Return
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Purpose of black tape on a white conductor?
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indentify that the conduct is being used as a hot or ungrounded conductor.
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which conductor is connected to the silver terminal on a fixture?
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White ; grounded conductor
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Why must you not cut off the ground when not used?
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for future used, and allows grounding if a conductor comes lose in the box
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How are travelers identified on a 3 way switch?
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brass colored terminals typically on the same side of switch
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How is the COMMON terminal identified on a 3 way switch? test question
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dark Colored typically identified by manufacture
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How are terminals identified on a 4 way?
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Set of dark and light colored terminals
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How many 3 way switches and 4 way switches will be needed to control a 5 entrance room of lights? test question
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minimal two 3 ways, and three 4 ways will be needed
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why are electrical systems grounded?
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Provides safety to those installing, using, and servicing the electrical system
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Per NEC: what residential electrical systems must be bonded?
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All low voltage, all electrical, and water infrastructure pipe.
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what does bonding accomplish?
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Reduces the difference of potential between metal parts in a dwelling
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what is grounding?
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Process of making a planned continuous connection between all non-current carrying metal parts of an electrical system
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what is grounded?
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being connected to earth ground conductor
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Purpose of grounding?
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To provide a path to de-energize the circuit if a short should accure
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What is the grounding electrode conductor
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NON insulated conductor.
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what happens when a current carrying conductor makes contact with grounded metal part?
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Short Circuit will result, tripping breaker, De-Energizing the circuit.
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Examples of Non current carrying parts?
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Wood, Plastic box
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What is bonding jumper?
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Conductor that bonds additional bus to existing bus bar.
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Four types of electrodes recognized by the NEC?
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Metal Ungrounded Water Pipes,Concrete Encased Electrodes, Grounding Ring, Metal Frame Work
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Installation requirements for a ROD and PIPE electrode?
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Rod: iron steel 5/8" diameter
Pipe: must be atleast 3/4 " not less than 8ft long, having direct contact with earth |
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Distance of grounding rods apart when used together?
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6 feet
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What determines the size of the grounding electrode conductor?
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Depends on the size of the service entrance conductor
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Why does the process of installing circuit breaker require special caution?
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life and death precautions need to be followed, possible electricusion
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What are the Black, White, and BARE conductors used for in a 120 volt circuit
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black: connected to circuit breaker/hot
white: neutral bus bar Bare: equipment grounding bus bar |
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what is the black, red, white, and bare used for ina 120/240 volt circuit?
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red & black are both connected to each circuit breaker, white is neutral bus bar, bare is equipment grounding bus bar
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what is the black, white, and bare conductors used for in a 240 volt circuit
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black and white are both connected to their own circuit breakers, bare is connected to neutral bus bar
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How to calculate the number of general circuits per sq foot of living space? test question
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You calculate your general lighting and general use receptacle load at 3 volt-amperes (VA) per square foot. This calculation equals (3VA x 2,000 square feet) 6,000 VA. So what does this mean? Well, 6,000 VA ÷ 120 volts = 50 amps. This means you need a minimum of 3 – 20 amp circuits or 4 – 15 amp circuits or a combination of the 2 totaling 50 amps or more for general lighting and general use receptacles
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