Electrical systems
Remote Control (RC) Switches
(SPECIAL SWITCHES) A contactor, or more specifically, a relay, that latches after being operated wireless from a distance.
Time Controlled Switches
(SPECIAL SWITCHES) This device comprises a precision low speed miniature drive motor (timer) to which some type of electric contact-making device is connected.
Automatic Transfer Switch (ATS)
(SPECIAL SWITCHES) This device, an essential part of an emergency or standby service, is basically a double throw switch, generally 3-pole, so arranged that on failure of normal power, emergency service is automatically supplied.
Knife Switch
(SPECIAL SWITCHES) a form of air switch in which a hinged copper blade is placed between two contact clips.
Float Switch
(SPECIAL SWITCHES) a switch controlled by a conductor floating in a liquid.
Air Switch
(SPECIAL SWITCHES) a switch in which the interruption of a circuit occurs in air.
Key Switch
(SPECIAL SWITCHES) a switch operated only by inserting a key or a card. Also called a card switch.
Mercury Switch
(SPECIAL SWITCHES) an especially quiet switch that opens and closes an electric circuit by shifting a sealed glass tube of mercury so as to uncover or cover the contacts.
UNIT SUBSTATIONS
(Transfer Load Centers) an assembly of primary switch-fuse-breaker, step-down transformer, meters, controls, bus bars and secondary switchboard. It is used to supply power from a primary voltage line to any large facility.
AVA
(Type of Insulators) -Asbestos and Varnished Cambric -Dry locations
THHN
(Type of Insulators) -Heat-resistant thermoplastic -Dry locations
XHHW
(Type of Insulators) -Moisture-& heat resistant cross-linked thermosetting polyethelene -Dry and wet Locations
RHW
(Type of Insulators) -Moisture-& heat-resistant rubber -Dry and wet Locations
THW
(Type of Insulators) -Moisture-& heat-resistant thermoplastic -Dry and wet Locations
THWN
(Type of Insulators) -Moisture-& heat-resistant thermoplastic -Dry and wet Locations
TW
(Type of Insulators) -Moisture-resistant thermoplastic -Dry and wet Locations
SA
(Type of Insulators) -Silicone-asbestos -Dry locations
T
(Type of Insulators) -Thermoplastic -Dry locations
AMPERE
(symbol: A), often shortened to "amp", is the base unit of electric current in the International System of Units (SI). It is named after André-Marie Ampère (1775-1836), French mathematician and physicist, considered the father of electrodynamics.
COULOMB
(symbol: C) is the International System of Units (SI) unit of electric charge
VOLT
(symbol: V) is the derived unit for electric potential, electric potential difference (voltage), and electromotive force. It is named after the Italian physicist Alessandro Volta (1745-1827).
WATT
(symbol: W) is a unit of power. It is an derived unit in the International System of Units (SI) defined as 1 joule per second and can be used to quantify the rate of energy transfer.
OHM
(symbol: Ω) is the SI derived unit of electrical resistance, named after German physicist Georg Simon Ohm.
WATT-HOURS
(symbolized Wh) is a unit of energy equivalent to one watt (1 W) of power expended for one hour (1 h) of time.
SINGLE PHASE ELECTRICAL SYSTEMS
-For homes and small commercial buildings -can either be 2-wire or 3-wire and composes two hot legs and a neutral wire.
THREE PHASE ELECTRICAL SYSTEMS
-For industries and large commercial buildings -is a Triple Circuit. The lighting and outlet loads are connected between any phase leg and a neutral line. While machineries and other bigger loads are connected to the phase leg only.
1. Armored Cable (Type AC) 2.Metal Clad Cable (Type MC) 3. Mineral Insulated Cable (Type MI) 4. Non-Metallic Sheathed Cable (Type NM or NMC) 5. Shielded Non-Metallic Sheathed Cable (Type SNM) 6. Underground Feeder and Branch Circuit Cable (Type UF) 7. Service Entrance Cable (Type SE or USE) 8. Power and Control Tray Cable (Type TC) 9. Flat Cable Assemblies (Type FC) 10. Flat Conductor Cable (Type FCC) 11. Medium Voltage Cable (MV)
1. AC 2.MC 3. MI 4. NM or NMC 5. SNM 6. UF 7. SE or USE 8. TC 9. FC 10. FCC 11. MV
1. Underfloor Ducts (UF) 2. Cellular Metal Floor Raceway 3. Precast Cellular Concrete
3 Types of floor raceways recognized by NEC
Panel
A board on which are mounted the switches, fuses and circuit breakers for controlling and protecting a number of similar branch circuits installed in a cabinet and accessible from the front only. Also called a panelboard.
General Purpose Circuit
A branch circuit that supplies current in a number of outlets for lighting and appliances
Appliance Circuit
A branch circuit that supplies current in one or more outlets specifically intended for appliances
Individual Circuit
A branch circuit that supplies current only to a single piece of electrical equipment
Ground Wire
A conductor connecting electric equipment or a circuit to a ground connection. Also called a grounding conductor
Grounding Electrode
A conductor, as a metal ground rod, ground plate or cold-water pipe, firmly embedded in the earth to establish a gorund connection
Fuse
A device containing a strip or wire of fusible metal that melts under the heat produced by excess current thereby interrupting the circuit
Lightning Arrester
A device for protecting electric equipment from damage by lightning or other high-voltage currents, using spark gaps to carry the current to the ground without passing through the device
FEEDER CIRCUITS
A feeder circuit is a set of conductors which extends from the main switchboard to a distributing center (panel board) with no other circuits connected to it between the source and the distributing center.
Transformer Vault
A fire-rated room housing a transformer and auxiliary equipment for a large building
Unit Substation
A freestanding enclosure housing a disconnect switch, a step-down transformer and switchgear
Bus
A heavy conductor, usually in the form of a solid copper bar, used for collecting, carrying and distributing large electric currents. Also called a busbar
BLOCK DIAGRAM
A horizontal single line diagram of the building's electrical system from the incoming service to the utilization items at the end of the system where the major electrical components are shown as blocks or rectangles.
Watt-Hour Meter
A meter for measuring and recording the quantity of electric power consumed with respect to time
Distribution Panel
A panel for distributing power to other panels or to motors and other heavy power-consuming loads. Controls, distributes and protects a number of similar branch circuits in an electrical system
Spark Gap
A space between two terminals or electrodes across which a discharge of electricity may pass at a prescribed voltage
Circuit Breaker
A switch that automatically interrupts an electric circuit to prevent excess current from damaging apparatus in the circuit or from causing a fire. A circuit breaker may be reclosed and reused without replacement of any components. Also called a breaker.
16, 0000
All conductor sizes from No. [,blank,] to No. [,blank,] (also designated 4/0) are expressed in AWG.
Alternating Current Generators
Also called alternator
Substation
An auxiliary power station where electrical current is converted or where voltage is stepped up or down
BRANCH CIRCUITS
An electrical circuit may be defined as a complete conducting path carrying current from a source of electricity to and through some electrical device or load and back to the source. The two wire circuit, which is the most elementary of all wiring systems, consists of a live wire carrying the current to the various power consuming devices in the circuit and a neutral or grounded wire which is the return wire carrying the circuit back to the source of supply.
Uninterruptible Power Supply
An emergency system designed to provide power automatically and instantaneously
Grounded Conductor
Any conductor of an electrical system intentionally connected to a ground connection
Lightning Rod
Any of several conducting rods installed at the top of a structure and grounded to divert lightning away from the structure. Also called air terminal
Feeder
Any of the conductors extending from the service equipment to various distribution points in a building
30 watts per square meter (3 watts per square foot)
Branch circuits shall be sufficient to supply a load of [,blank,] watts per square meter ([,blank,] watts per square foot) in buildings excluding porches, garages and basements.
1. General purpose branch circuit 2. Appliance branch circuit 3. Individual branch circuit
CLASSIFICATIONS OF BRANCH CIRCUITS
Battery Equipment
Central storage batteries are mounted in individual racks and always provided with automatic charging equipment.
Switchgear Room
Contains the service equipment for a large building
2
Convenience receptacles in an area shall be wired to at least [,blank,] different circuits so that in case of failure in any one of the circuits, the entire area will not be deprived of power.
3&4 WIRES CIRCUIT NO. MARK INDICATES 2 WIRES
Electrical Symbols
ANNUNCIATOR
Electrical Symbols
BELL
Electrical Symbols
BRANCH CIRCUIT-CEILING/WALL
Electrical Symbols
BRANCH CIRCUIT-FLOOR
Electrical Symbols
BUZZER
Electrical Symbols
CHIME
Electrical Symbols
CLOCK OUTLET
Electrical Symbols
CONNECTING WIRES
Electrical Symbols
CONVENIENCE OUTLET SPLIT-WIRED
Electrical Symbols
CROSSING WIRES
Electrical Symbols
DROP CORD OUTLET
Electrical Symbols
DUPLEX CONVENIENCE OUTLET
Electrical Symbols
FAN OUTLET
Electrical Symbols
FLOOR OUTLET
Electrical Symbols
FLUORESCENT LAMP
Electrical Symbols
FUSE
Electrical Symbols
Feeder
Electrical Symbols
GROUND
Electrical Symbols
JUNCTION BOX
Electrical Symbols
LAMP HOLDER
Electrical Symbols
LAMP HOLDER WITH PULL SWITCH
Electrical Symbols
LIGHTING OUTLET CEILING
Electrical Symbols
LIGHTING OUTLET WALL
Electrical Symbols
LIGHTING PANEL
Electrical Symbols
OUTLET AND SWITCH
Electrical Symbols
POWER PANEL
Electrical Symbols
PUSH BUTTON
Electrical Symbols
RADIO OUTLET
Electrical Symbols
RANGE OUTLET
Electrical Symbols
RECESSED CEILING OUTLET DASH INDICATES SHAPE OF FIXTURE
Electrical Symbols
REFRIGERATOR OUTLET
Electrical Symbols
SPECIAL PURPOSE OUTLET
Electrical Symbols
TRANSFORMER
Electrical Symbols
WATT-HOUR METER
Electrical Symbols
WEATHER PROOF OUTLET
Electrical Symbols
Service Equipment
Equipment necessary for controlling, metering and protecting the electric power supply to a builidng
Standby Generator
For providing emergency power during a power outage.
20 amperes; No. 12 AWG minimum; No. 14 AWG
General purpose branch circuits shall be rated at [,blank,] amperes wired with No. [,blank,] AWG minimum. Switch legs may be No. [,blank,] AWG if the lighting load permits.
Rigid Steel Conduits" or RSC
Heavy-wall steel conduits called with an approximate thickness of 0.117 mm.
2 - 20 amperes
In all but the smallest installations, connect lighting, convenience receptacles, and appliances in separate circuits. The Code requires a mi nimum of [,blank,] - [,blank,] amperes appliance branch circuit to feed all small appliance outlets in the kitchen, pantry, dining and family room.
RISER DIAGRAM
Is a vertical line diagram of the major electrical components of the buildings electrical system presented showing the spatial relations between components.
Grounding Rod or Electrode
Is firmly embedded in the earth to establish a ground connection
FLEXIBLE METAL CONDUIT WIRING
Its installation is much easier and quicker than that of rigid metal conduits. Unlike the rigid conduits which come in short lengths of 10 ft. (3 M), this comes in length of 25 ft - 250 ft (8 M - 83 M) depending on the size of the conduit.
15 amp and 20 amp; 15 and 20 amp
Limit the circuit load for lighting and small appliances on [,blank,] amp and [,blank,] amp circuit loads and on [,blank,] and [,blank,] amp overcurrent devices respectively.
Watt-Hour Meter
Measures and records the quantity of electric power consumed with respect to time. Supplied by the public utility, it is always placed ahead of the main disconnect switch so that it cannot be disconnected For multiple-occupancy buildings, banks of meters are installed so that each unit can be metered independently
Low-Voltage
Of or pertaining to a circuit in which alternating current below 50 volts is supplied by a step-down transformer form the normal line voltage used in residential systems to control doorbells, intercoms, heating and cooling systems and remote lighting fixtures. Low-voltage circuits do not require a protective raceway
I (amp) = V (Volts) / R (Ohms)
Ohm's law (equation)
Switchboard
One or a group of panels on which are mounted switches, overcurrent devices, metering instruments and buses
condulets
RSCs and IMCs use the same fitting, called [,blank,], and are threaded alike at the joints.
1. Time Controlled Switches 2. Remote Control (RC) Switches 3. Air Switch 4. Knife Switch 5. Float Switch 6. Mercury Switch 7. Key Switch 8. Automatic Transfer Switch (ATS)
SPECIAL SWITCHES
1. STORAGE BATTERIES 2. GENERATORS
Sources of electricity
3 M or 10 ft.
Standard length of steel conduits
1. Normal Duty (ND) 2. Heavy Duty (HD) 3. Light Duty (LD)
TYPE OF SWITCH - ACCORDING TO INTENSITY OF USE
1. Single Pole Single Throw (SPST) 2. Single Pole Double Throw (SPDT) 3. Double Pole Single Throw (DPST) 4. Double Pole Double Throw (DPDT)
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
Double Pole Double Throw (DPDT)
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
Double Pole Single Throw (DPST)
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
Single Pole Double Throw (SPDT)
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
Single Pole Single Throw (SPST)
TYPE OF SWITCH - ACCORDING TO NUMBER OF POLES AND THROWS
1. Rotary switch 2. Push-button switch 3. Toggle or tumbler switch
TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM
Push-button switch
TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM
Rotary switch
TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM
Toggle or tumbler switch
TYPE OF SWITCH - ACCORDING TO OPERATION MECHANISM
1. Service Switch 2. Power Switches 3. Wiring Switches
TYPE OF SWITCH - ACCORDING TO TYPE OF SERVICE
1. 250V 2. 600V 3. 5kV
TYPE OF SWITCH - ACCORDING TO VOLTAGE
250V
TYPE OF SWITCH - ACCORDING TO VOLTAGE
5kV
TYPE OF SWITCH - ACCORDING TO VOLTAGE
600V
TYPE OF SWITCH - ACCORDING TO VOLTAGE
Ohm's law
The current, I, that will flow in a d-c circuit is directly proportional to the voltage ,V, and inversely proportional to the resistance, R, of the circuit.
Line Drop
The decrease in voltage between two points on a power line, usually caused by resistance or leakage along the line
Service Switch
The main disconnect for the entire electrical system of a building except for any emergency power systems
Service Drop
The overhead portion of service conductors extending from the nearest utility pole to a building
Service Entrance Conductor
The portion of a service conductor extending from a service drop or service lateral to the service equipment of a building
Branch Circuit
The portion of an electrical system extending from the final overcurrent device protecting a circuit to the outlets served by the circuit
MAIN SWITCHBOARD
The service entrance conductors in the form of bus bars terminates in the main switchboard and connects to the distribution panel boards by means of feeder circuits protected by circuit breakers. The main switchboard serves for the control, protection and metering of the main feeders.
Service
The supplying of utilities required or demanded by the public
Service Lateral
The underground portion of service conductors extending from a main power line or transformer to a building
WALL PLATES OR FACEPLATES
These are coverings for switches and wall outlets usually made of metal or of phenollic compound (Bakelite).
BRANCH CIRCUITS
These are small capacity conductors which deliver energy to lamps, motors and other loads within the circuit.
UTILIZATION EQUIPMENT
These are the lighting, power and motor loads and wiring devices which are directly handled and utilized by users.
Direct Current Generators
These furnish electrical energy for elevators, escalators, intercommunicating telephone systems, control of signal systems, and clock systems.
PANEL BOARDS AND SUB-PANEL BOARDS (also called CUT-OUTS)
These serve to control and protect the sub feeders and branch circuits.
Electric Metal Tubing" or EMT
Thin-wall steel conduits.
IDEALCURVE CONTROL
This controller operates by comparing the actual rate of energy usage to the ideal rate, and controls KW demand by controlling the total energy used within a metering interval.
KWH METERS
To measure energy, the factor of time is introduced, such that; energy = power x time. A-C electric meters are basically small motors, whose speed is proportional to the power being used. The number of rotations is counted on the dials which are calibrated directly in kilowatt-hours.
Cellular Metal Floor Raceway
Type of floor raceway found usually in office landscaping, it is an integrated structural/electrical system in a cellular metal floor.
Underfloor Ducts (UF)
Type of floor raceway installed beneath or flush with the floor. These underfloor ducts usually requires a triple duct system for power, telephone and signal cabling.
Precast Cellular Concrete
Type of floor raceway made of concrete cells fed from header ducts, which are normally installed in concrete fill above the hollow core structural slab or fed from the ceiling void below. The cells can be used for air distribution and for piping.
Disconnecting or isolating switches
Type of power switches intended for disconnecting or isolating circuits; used for circuits rated at more than 600 volts.
General -purpose switches
Type of power switches intended for use in general distribution and branch circuits.
Heavy Duty (HD)
Type of switch according to intensity of use intended for frequent interrupting.
Normal Duty (ND)
Type of switch according to intensity of use intended for normal use in light and power circuits as in general-purpose switches.
Light Duty (LD)
Type of switch according to intensity of use intended to connect the loads occasionally, such as service switches.
Service Switch
Type of switch according to type of service intended to disconnect all the electric service in the building except emergency equipment. This may comprise one to six properly rated switches that are assembled into a switchboard.
Wiring Switches
Type of switch according to type of service which include all the relatively small switches that are employed in interior wiring installations for the control of branch circuits, individual lamps or appliances.
1. AC 2.MC 3. MI 4. NM or NMC 5. SNM 6. UF 7. SE or USE 8. TC 9. FC 10. FCC 11. MV
Types of cables
1. Alternating current 2. Direct current
Types of current
1. General -purpose switches 2. Disconnecting or isolating switches
Types of power switches
1. Flush type 2. Surface type 3. Pendant type
Types of wiring switch according to form
flush type
Types of wiring switch according to form
pendant type
Types of wiring switch according to form
surface type
Types of wiring switch according to form
1. General -purpose switches 2. Three-way switches 3. Four-way switches 4. Electrolier or multi-circuit switches 5. Momentary contact switches 6. Dimmer switches
Types of wiring switches
Dimmer switches
Types of wiring switches is a rheostat or similar device for regulating the intensity of an electric light without appreciably affecting spatial distribution. Also called a dimmer.
General-purpose switches
Types of wiring switches which are single-pole or double-pole switches for the general purpose use of connecting or cutting-off circuits for the control of lamps or other loads from a single point.
Electrolier or multi-circuit switches
Types of wiring switches which are used for the control of lights in multi-lamp fixtures so that one lamp or set of lamps may be turned on alone or in combination with other lamps.
Four-way switches
Types of wiring switches which are used in conjunction with two 3-wire switches where it is desired to control lamps from three or more desired points.
Momentary contact switches
Types of wiring switches which are used where it is desired to connect or cut-off a circuit for only a short duration. The switch is provided with a spring so that it will return to its original position as soon as the handle or button is released.
Three-way switches
Types of wiring switches which are used where it is desired to control lamps from two different points, as in a stairwell.
1. KNOB AND TUBE WIRING 2. RIGID METAL CONDUIT WIRING 3. FLEXIBLE METAL CONDUIT WIRING 4. ARMORED CABLE WIRING (BX WIRING) 5. SURFACE METAL RACEWAY WIRING 6. FLAT CABLE ASSEMBLIES 7. LIGHTING TRACK 8. CABLE TRAY / OPEN RACEWAY 9. FLOOR RACEWAYS 10. CEILING RACEWAY SYSTEMS 11. PRE-WIRED CEILING DISTRIBUTION SYSTEMS
WIRING METHODS
FLOOR RACEWAYS
WIRING METHODS
SINGLE LINE DIAGRAM
When electrical symbols are used in lieu of the blocks, it is called a "one line" or a "single line diagram".
DIRECT CURRENT
a current which flows at a constant time rate and in the same direction.
ALTERNATING CURRENT
a current which is periodically varying in time rate and in direction. It rises from zero to maximum, falls to zero, reverses its direction and again returns to zero.
Armored Cable (Type AC)
a fabricated assembly of insulated conductors enclosed in flexible metal sheath.
Metal Clad Cable (Type MC)
a factory assembled cable of one or more conductors each individually insulated and enclosed in a metallic sheath of interlocking tape of a smooth or corrugated tube.
Mineral Insulated Cable (Type MI)
a factory assembled conductor/s insulated with a highly compressed refractory mineral insulation enclosed in a liquid and gas tight continuous copper sheath.
Power and Control Tray Cable (Type TC)
a factory assembled two or more insulated conductors with or without associated bare or covered grounding under a metallic sheath and is used for installation in cable trays, raceways, or where supported by wire.
Shielded Non-Metallic Sheathed Cable (Type SNM)
a factory assembly of two or more insulated conductors in an extruded core of moisture resistant and flame retardant material covered within an overlapping spiral metal tape.
LIGHTING TRACK
a factory-assembled channel with conductors for one to four circuits permanently installed in the track that will act as light duty (branch circuit) plug-in busways.
FLAT CABLE ASSEMBLIES
a field installed rigidly mounted square structural channel (1 - 5/8" standard) designed to carry 2 to 4 conductors (No. 10 AWG) and will act as light duty (branch circuit) plug-in busways.
Underground Feeder and Branch Circuit Cable (Type UF)
a moisture resistant cable used for underground connections including direct burial in the ground as feeder or branch circuit.
Service Entrance Cable (Type SE or USE)
a single or multi-conductor assembly provided with or without an overall covering primarily used for service wire.
Medium Voltage Cable (MV)
a single or multi-conductor solid dielectric insulated cable rated at 2,000 to 35,000 volts. Trade name is Medium Voltage Solid Dielectric.
Throws
a single throw switch is one which will make a closed circuit only when the switch is thrown in one position. A double throw switch will make a closed circuit when thrown in either of two positions.
AUTOMATIC INSTANTANEOUS DEMAND CONTROL
also called "rate control", it is an automated version of the demand metering alarm system, where it automatically disconnects or reconnects loads as required.
Non-Metallic Sheathed Cable (Type NM or NMC)
also known by the trade name ROMEX, is a factory assembly of two or more insulated conductors having a moisture resistant, flame retardant, and non-metallic material outer sheath.
Flat Cable Assemblies (Type FC)
an assembly of parallel conductors formed integrally with an insulating material web designed specially for field installation in square structural channels.
KNOB AND TUBE WIRING
an obsolete wiring system consisting of single insulated conductors secured to and supported on porcelain knobs and tubes. When wires run through walls, they are inserted into a nonmetallic fire-resistant tubing called a loom.
PRE-WIRED CEILING DISTRIBUTION SYSTEMS
are ceiling raceways that are pre-wired in the factory and plugged in where required.
RACEWAYS
are channels or wiring accessories so designed for holding wires, cables and bus bars that are either made of metal, plastic, or any insulating medium.
CONDUITS
are circular raceways used to enclose wires and cables and are of metal or plastic (PVC).
FORECASTING SYSTEMS
are computerized systems which continuously forecast the amount of energy remaining in the demand interval, then examine the status and priority of each of the connected loads and decide on the proper course of action.
SWITCHES
are devices for making, breaking, or changing conditions in an electrical circuit under the conditions of load which they are rated.
OVER-CURRENT CIRCUIT PROTECTIVE DEVICES
are devices whose sole purpose is to protect insulation, wiring, switches and other apparatus from overheating or burning, due to overloads, to faults or to short circuits, by automatically cutting off the circuit.
SWITCHBOARDS
are free standing assemblies of switches, fuses, and/or circuit breakers whose function normally is to provide switching and feeder protection to a number of circuits connected to a main source.
SUB-FEEDER CIRCUITS
are line extensions of a feeder, fed through a panel board or cut-out, or from one distributing center to another and having no other circuit connected to it between the two distributing centers. A sub-feeder serves to distribute power from the main feeders to smaller local panel boards, called sub-panel boards.
Engine-Generator Sets
are machines intended to produce electricity and composed of three components: the machine and its housing (if any), fuel storage tank and the exhaust facilities.
INSULATORS
are materials which prevent the flow of electrons through them.
EMT
are not threaded but use set screw and pressure fitting and are not recommended for embedding in concrete nor permitted in hazardous areas.
Cables
are single insulated conductors No. 6 AWG or larger; or they may be several conductors of any size assembled into a single unit.
Wires
are single insulated conductors No. 8 AWG (American Wire Gauge or smaller; for the English System, it is the B & S Gauge or Browne and Sharpe Gauge. The smallest size of wire permitted is No. 14.
STORAGE BATTERIES
are used to supply emergency lighting circuits for hallways, stairways, exits and to energize police and fire alarm systems and certain types of signal systems.
500 MCM
biggest MCM size
ROTARY CONVERTERS
changes alternating current to direct current and vice versa.
Intermediate Metal Conduit or IMC
conduits with thickness of 0.071 mm.
ARMORED CABLE WIRING (BX WIRING)
consists of rubber or thermoplastic covered wire protected from injury to a certain extent from dampness by one or two layers of flexible steel armor.
Flat Conductor Cable (Type FCC)
consists of three or more flat copper conductors placed edge to edge separated and enclosed within a insulating assembly. This type of cable is used for appliance or individual branch circuits installed inside floor surfaces.
MOTORS
converts electrical energy to mechanical energy.
TRANSFORMERS
converts one voltage to another, from lower to higher or from higher to lower
Service Conductors
extend from a main power line or transformer to the service equipment of a building
GENERATORS
for generating electric current
DEMAND METERING ALARM
in conjunction with a duty cycle controller, demand is continuously metered and an alarm is set on when a predetermined demand level is exceeded.
service equipment
includes a main disconnect switch and secondary switches, fuses and circuit breakers for controlling and protecting the electric power supply to a building. It is located in a switchgear room near the entrance of the service conductors
CABLE TRAY / OPEN RACEWAY
is a continuous open support for approved cables. When used as a general wiring system, the cables must be self-protected, jacketed types, type TC.
FUSE
is a device consisting of an alloy link of wire with a low melting temperature which is inserted in the circuit, in such a way, that all current which passes through the circuit, must also pass through this metal.
main switchboard
is a panel on which are mounted switches, overcurrent devices, metering instruments and busbars for controlling, distributing and protecting a number of electric circuits
OUTLET
is a point in the wiring system at which current is taken to supply utilization equipment. It refers only to the box.
circular MIL
is an artificial area measurement, representing the square of the cable diameter (diam²)when the diameter is expressed in mils (thousands of an inch). Thus a solid conductor ½ inch in diameter is 500 mils in diameter, or 250,000 circular mils in area, (500)² or 250 MCM
Lighting Outlet
is an outlet intended for direct connection to a lamp holder, lighting fixture, or pendant cord terminating in a lamp holder.
Receptacle Outlet
is an outlet where one or more receptacles are installed.
GROUND FAULT CIRCUIT INTERRUPTERS (GFCI or GFI)
is an over current protective device that will provide ground fault protection as well as function as an ordinary circuit breaker.
CIRCUIT BREAKERS
is an over-current protective device designed to function as a switch, or it can be manually tripped and thus act as a circuit switch. It breaks a circuit with an automatic tripping device without injury to itself.
Individual Branch Circuit
is designed to supply a single specific item, such as a motor load or a unit airconditioner.
SERIES CIRCUIT
is one in which the components are connected in tandem. All separate loads of the circuit carry the same equal current and the total resistance, R, is the sum of the resistances around the circuit.
PARALLEL CIRCUIT (or Multiple Circuit)
is one in which the components or loads are so arranged that the current divides between them. Each outlet has a live wire connected to the current carrying wire of the circuit and also a neutral wire or grounded wire connected to the return wire of the circuit. With this system, the total current flowing through the circuit is the sum of the current flowing through each outlet.
RIGID METAL CONDUIT WIRING
is the best and most expensive among the usual type of wiring. Its advantages are: 1. it is fireproof; 2. moisture proof; 3. it is mechanically strong so that nails cannot be driven through it and it is not readily deformed by blows; 4. it resists the normal action of cement when embedded in concrete or masonry.
ELECTRIC LOAD CONTROL
is the effective utilization of available energy by reducing peak loads and lowering demand charge. The control devices and systems are referred to as load shedding control, peak demand control, peak load regulation, and power use control.
service switch
is the main disconnect for the entire electrical system of a building, except for any emergency power systems.
Conductor current carrying capacity or ampacity
is the maximum operating temperature that its insulation can stand continuously.
receptacle
is the wiring device in which the utilization equipment (appliance) cord is plugged into.
Bus Bars
large conductors which are not circular in cross section and usually found only to supply the main switch boards.
Direct burial cable
may be used for residential service connections
thousand circular mil
meaning of MCM
PANELBOARDS
popularly known as "panel" or "electrical panel", it is simply the box wherein the protective devises are housed from which the circuits and bus bars terminate.
Emergency Systems
provide electric power and illumination essentially for life safety and protection of property during an emergency, such as, electricity for exit lighting, elevators, fire alarm systems, fire pumps and the like.
Standby Systems
provide power to selected loads not directly involved with life safety, such as, water and sewage treatment plants and industrial machines for manufacturing processes.
transformer
s used by medium-sized and large buildings to step down from a high supply voltage to the service voltage. To reduce costs, maintenance and noise and heat problems, a transformer may be placed on an outdoor pad. If located within a building, oil-filled transformers require a well-ventilated, fire-rated vault with two exits and located on an exterior wall adjacent to the switchgear room. Dry-type transformers used in small- and medium-sized buildings may be replaced together with a disconnect switch and switchgear in a unit substation
250 MCM or ½" Ø
smallest MCM size
General Purpose Branch Circuit
supplies outlets for lighting and appliances, including convenience receptacles.
Appliance Branch Circuit
supplies outlets intended for feeding appliances. Fixed lighting is not supplied.
Poles
that part of the switch which is used for making or breaking of a connection and which is electrically insulated from other contact making or breaking parts.
Convenience Outlet or Attachment Cap
the complete set-up which establishes connection between the conductor of the flexible cord and the conductors connected permanently to the receptacle.
LOAD SCHEDULING AND DUTYCYCLE CONTROL
the installation's electric loads are analyzed and scheduled to restrict demand by shifting large loads to off-peak hours and controlled to avoid coincident operation.
SERVICE ENTRANCE
the point of delivery of electricity to a building by a public utility company.
SURFACE METAL RACEWAY WIRING
the wires are supported on a thin sheet steel casing. The raceway is installed exposed, being mounted on the walls or ceiling. Metal raceways must be continuous from outlet to outlet or junction box, designed especially for use with metal raceways.
mils
thousands of an inch
CEILING RACEWAY SYSTEMS
under-the-ceiling raceways composed of header ducts and distribution ducts separate for power and telephone cabling. They permit very rapid changes in layouts at low cost and are therefore particularly desirable in stores where frequent display transformations necessitate corresponding electrical facility adjustments.
RSCs and IMCs
use the same fitting, called condulets, and are threaded alike at the joints.
IMC
yield a larger inside diameter (ID) for easier wire pulling and is lighter than the RSC.
Electricity
• a form of energy generated by friction, induction or chemical change, having magnetic, chemical and radiant effect. • the motion of free electrons through a solid conductor.
