ELECTRICAL NOTES

Electrical Notes:
COULUMB (C)
- The SI unit of electric charge equal to the quantity of electricity transferred along the conductor by a current of one ampere in one second

WATT (W)
- the SI unit equal to one joule per second or to the power represented by a current of one ampere flowing across a potential difference of one volt
W= V x A

WATTAGE
- an amount of power especially the power required to operate an electrical device or appliance, expressed in watts

KILOWATT (kW)
- a unit of power equal to 1,000 watts

KILOWATT-HOUR (kWh)
- a unit of energy transferred or expanded by one kilowatt in one hour a common unit of electric power consumption

ELECTROMOTIVE FORCE (emf)
- the energy per unit charge available for conversion from a chemical, mechanical or other form of energy into electrical energy or vice versa in a conversion devise as a battery, generator or a motor

POTENTIAL DIFFERENCE
- the voltage difference between two points that represents the work involved in the transfer of a unit charge from one point to the other

POTENTIAL
- the work required to move a unit charge from a reference point to a designed point

VOLTAGE
- potential difference or electromotive force expressed in volts: analogous to pressure in water flow

VOLT (V)
- the SI unit of potential difference and electromotive force, defined as the difference of electric potential between two points of a conductor carrying a constant current of one ampere, when the power dissipated between the points is equal to one watt

CURRENT
- the rate of flow of electric charge in a circuit per unit time measured in amperes

AMPERE (A)
- the basic SI unit of electric current, equivalent to a flow of one coulomb per second or to the steady current produced by one volt applied to one resistance of one ohm

AMPERAGE
- the strength of an electric current measured or expressed in amperes: analogous to the rate of water flow

RESISTANCE (R)
- the opposition of a conductor to the flow of current, causing some of the electric energy to be transformed into heat and usually measured in ohms
OHM
- the SI unit of electrical resistance, equal to the resistance of a conductor in which a potential difference of one volt produces a current of one ampere

OHM’S LAW
- that law that for any circuit the electric current is directly proportional to the voltage and inversely proportional to the resistance
I= V/R

JOULE’S LAW
- the principle that the rate of production of heat by direct current is directly proportional to the resistance of the circuit and to the square of the current

RESISTIVITY
- the resistance per unit length of a substance with a cross sectional area. Also called specific resistance

CONDUCTIVITY
- a measure of the ability of a substance to conduct electric current, equal to the reciprocal of the resistivity of the substance. Also called specific conductance

CIRCUIT
- the complete path of an electric current including the source of electric energy

SERIES
- an arrangement of components in an electric circuit in which the same current flows through each component in turn without branching

PARALLEL
- the arrangement of components in an electric circuit in which all positive terminals are connected to a second conductor, the same voltage being applied to each component

BATTERY
- a group of two or more cells connected together to produce electric current

CELL
- a device for converting chemical into electric energy usually consisting of a receptacle with electrodes in an electrolyte. Also called electric cell

ELECTROLYTE
- a non metallic conducting medium in which current is carried by the movement of ions

ELECTRODE
- a conductor through which a current enters or leaves a non metallic medium

ANODE
- the negative terminal of a primary cell or storage battery

CATHODE
- the positive terminal of a primary cell or storage battery

GENERATOR
- a machine that converts mechanical energy into electric energy

ALTERNATOR - a generator for producing alternating current
ELECTRIC MOTOR
- a machine that converts electric power into mechanical energy

ARMATURE
-the main current-carrying winding of a motor or generator in which electromotive force is induced

DIRECT CURRENT (DC)
- an electric current in one direction only having a magnitude that does not vary or varies only slightly

ALTERNATING CURRENT (AC)
- an electric current that reverses direction at regularly recurring intervals, having a magnitude that varies in a sinusoidal manner

VOLT AMPERE (VA)
- a unit of electric measurement equal to the product of one volt and one ampere, equivalent to one watt for direct current system and a unit of apparent power for alternating current systems

TRANSFORMER
- an electric device consisting of two or more winding wound on the same core, which employs the principle of mutual induction to convert variations of alternating current in a primary circuit into variations of voltage and current in a secondary circuit

STEP-UP TRANSFORMER
- a transformer having fewer turns in the primary winding than in the secondary, serving to transform low voltage to high voltage

STEP-DOWN TRANSFORMER
- a transfer having a greater number of turns in the primary winding than in the secondary, serving to transform high voltage to low voltage

LINE VOLTAGE
- the voltage supplied by a power line, measured at the point of use

SERVICE CONDUCTOR
- any of several conductors extending from a main power line or transformer to the service equipment of a building

SERVICE
- the supply of utilities, as water, gas and electricity, required or demanded by the public

HIGH VOLATGE
- operated on power by or transmitting high voltage

SUBSTATION
- an auxiliary power station where electrical current is converted, as from DC to AC or where voltage is stepped up or down

SERVICE DROP
- the overhead portion of service conductors extending from the nearest utility pole to a building

SERVICE LATERAL
- the underground portion of service conductors extending from a main power line or transformer to a building

LINE DROP
- the decrease in voltage between two points on a power line, usually caused by resistance or leakage along the line

SERVICE ENTRANCE CONDUCTOR
- the portion of a service conductor extending from a service drop or service lateral to the service equipment of a building

WATT- HOUR METER
- a meter for measuring and recording the quality of electric power consumed with respect to time

TRANSFORMER VAULT
- a fire-rated room housing a transformer and auxiliary equipment for a large building, usually located on grade or below ground and ventilated directly to the outside air

SWITCHGEAR ROOM - a room containing the service equipment for a large building

SERVICE EQUIPMENT
- the equipment necessary for controlling, metering, and protecting the electric power supply to a building, located near the entrance of the service conductors and usually consisting of a main disconnect switch and secondary switch, fuses and circuit breakers

STANDBY GENERATOR
- a generator for providing emergency power during a power outage. Also called emergency generator

UNINTERRUPTIBLE POWER SUPPLY
- an emergency system designed to provide power automatically and instantaneously upon failure of the normal power supply

SWITCHBOARD
- one or a group of panels on which are mounted switches, over current devices, metering instruments, and buses for controlling and protecting a number of electric circuits called switchgear

UNIT SUBSTATION
- a free standing enclosure housing a disconnect switch, a step-down transformer and switchgear for a number of electric circuit

FEEDER
- any of the conductors extending from the service equipment to various distribution points in a building

WIRE
- a pliable metallic strand or twisted or woven assembly of such strands often insulated with a dielectric material and used as a conductor of electricity

CONDUCTOR - a substance, body or devise that conducts heat, sound or electricity

INSULATOR
- a material that is poor conductor of electricity used in operating or supporting conductors to prevent the undesired flow of current

CABLE - a single insulated conductor or a bound or sheathed combination of conductors insulated from one another

ARMORED CABLE
- electric cable consisting of two or more insulated conductors protected by flexible, helically wound metal wrapping. Also called BX

MINERAL ISULATED CABLE
- electric cable consisting of a tubular copper sheath containing one or more conductors embedded in a highly compressed, insulating refractory mineral

NON- METALLIC SHEATED CABLE
- electric cable consisting of two or more insulated conductors enclosed in a non- metallic, moisture resistant, flame retardant sheath. Also called ROMEX

COAXIAL CABLE
- a cable for transmitting high frequency telephone, digital or television signals consisting of an insulated conducting core

SHIELDED CABLE - an electric cable enclosed within a metallic sheath in order to reduce the effects of external electric or magnetic fields

CONDUIT - a tube, pipe or duct for enclosing and protecting electric wires or cable

RIGID METAL CONDUIT
- heavy-walled, tubular steel conduits joined by screwing directly into a threaded hub with locknuts and bushings

ELECTRICAL METAL TUBING (EMT)
- thin-walled, tubular steel conduit joined by compression or setscrew couplings

FLEXIBLE METAL CONDUIT
- flexible, helically wound metal conduit, used for connections to motors or other vibrating equipment. Also called Greenfield conduit

RACEWAY - a channel expressly designed to hold and protect electric wires and cables

SURFACE RACEWAY - a raceway designed to exposed installation in dry, non-hazardous, corrosive locations

MULTI- OUTLET ASSEMBLY - a surface mounted raceway designed to house the electrical wires for a circuit and a series of receptacles

DUCT - an enclosed runway for housing conductors or cables

BUS DUCT - a rigid metal housing for a group of buses insulted from each other and the enclosure. Also called busway

CABLE TRAY - an open metal framework for supporting insulated electrical conductors

BREAKDOWN VOLTAGE
- the minimum applied voltage at which a given insulator breaks down and permits current to pass

DIELECTRIC STRENGTH - the maximum voltage that can be applied to a given material without causing it to breakdown, usually expressed in volts or kilovolts per unit of thickness

DIELECTRIC - a non-conducting substance

JUNCTION BOX
- an enclosure for housing and protecting electric wires or cables that are joined together in connecting or branching electric circuits

KNOCKOUT - a panel in a casing or box that can readily be removed, as by punching, hammering or cutting to provide an opening into the interior

GROMMET - a rubber or plastic washer inserted in a hole in a metal part to prevent grounding of a wire passing through the hole

BUSHING - an insulating and protective lining for one or more conductors passing through a hole

UTILITY BOX - for lighting outlet and convenience outlet

PULL BOX - to facilitate pulling

OUTLET BOX - where cable ends

CUT OUT BOX - metal box with hinge & enclosure. House or fuse box

INSULATOR - used as supports and for additional protection for wires

GENERAL WIRING

RHW Moisture and heat resistance rubber Dry and wet locations
T Thermoplastic Dry locations
TW Moisture resistant thermoplastic Dry and wet locations
THHN Heat resistant thermoplastic Dry locations
THW Moisture & heat resistant thermoplastic Dry and wet locations
THWN Moisture & heat resistant thermoplastic Dry and wet locations
XHHW Moisture & heat resistant cross linked Dry and wet locations
SA Silicone asbestos Dry locations
AVA Asbestos and varnished cambric Dry locations only

CONDUIT FITTINGS:

1. elbow (long sweep)
2. tee
a. LB Condulets (angle & bended)
b. LR (angle to the right)
c. TF (tee front)

CONDUITS:

1. RIGID CONDUITS- cannot be bended
metal- RSC/ EMT
non-metal- PVC

2. FLEXIBLE
metal- BX