Quick study home electrical 600dpi

= = P Power Watts I = Intensity of Current Flow = Amps E Electromotive Force Volts R = Resistance (0 or Ohms) Most of Ohm 's Law can be solved by remembering two words: pie and ear (in this case, spelled " eir") = = EX: To find the formula for the missing value, place your finger over that symbol HOW TO CALCULATE THE MONTHLY ELECTRICITY COST FOR APPLIANCES Take the wattage (NOT kilowatts) of your appliance and divide it by 1,000 Multiply the product of step by the cost of electricity per KW/HR from your power supplier (TIP: This is the cost per hour to operate the appliance.) Multiply the cost per hour (step 2) by the estimated number of hours the appliance will be used per day Multiply cost per day (result of step 3) by number of days in the month (use 30 as an average) to determine the monthly cost of using a particular appliance e e o o WHat is the current in a 120-volt circuit with a load of 1,800 watts? I = PIE = 1,800 I 120 = 15 amps What is the power consumed in watts for a 240-volt circuit with a current draw of 25 amps? P = I x E =25 x 240 =6 ,000 watts What is the voltage of a circuit with a resistance of 12 and a current draw of 10 amps? E = I x R = 10 x 12 = 120 volts What is the current draw of a circuit with a voltage of 240 volts and a resistance of 25 O? I = E I R = 240 I 25 = 9.6 amps e e o RESISTORS The total resistance of a circuit with resistors wired in series is equal to the sum of the resistors : RT =R, + R2 + R"' The total resistance of a circuit with all resistors having the same value wired in parallel is equal to the size of the resistors divided by the number of resistors : RT = Size of Resistors Number of Resistors The total resistance of a circuit with unequal resistors wired in parallel is equal to the reciprocal of the sum of the reciprocals of all of the resistors in the circuit: RT = 1/R, + 1/R2 + 1/R3 EX : o What is the total resistance of a circuit with 3-12 resistors wired in series? RT = 12 + 12 + 12 =36 e What is the total resistance of a circuit with 3-12 resistors wired in parallel? RT =12 / 3=40 e What is the total resistance of a circuit with 1-60, 1-8 o and 1-12 resistors wired in parallel? RT= _ _ '-_ _ 1/R, + 1/R, + 1/R, SAMPLE CALCULATION OF COST TO OPERATE A 4,500-WATT ELECTRIC WATER HEATER ,500 walts -;- 1,000 =4.5 KW 4.5 x 09 =$0.41 per hour $0.41 x hours per day = $1.64 $1.64 per day x 30 days =$49.20 per month to operate (based on hours per day use and electricity costs of 9¢ per KW/HR) ~ 14¢ 17¢ 20¢ 23¢ 54¢ 66¢ 78¢ 90¢ 3.6¢ 4.4¢ 5.2¢ 6.0¢ 10.8¢ 13.2¢ 15.6¢ 180¢ 13.5¢ 16.5¢ 19.5¢ 22.5¢ 16.2¢ 19.8¢ 23.4¢ 27.0¢ 18.0¢ 220¢ 26.0¢ 30.0¢ 37.8¢ 46.2¢ 54.6¢ 630¢ 40.5¢ 49.5¢ 58.5¢ 67.5¢ 720¢ 88.0¢ $1.04 $1.20 m Z ~ " , u " 1\';:' 'uU Switch Row-To's 1-POLE SWITCH 3-WAY SWITCH For illustration clarification, grounding conductors are not shown ~ -2 conductor wi grou nd NM cable Incoming Power I Single Po'! Switch I ~ For illu stration clarification, ground ing conductors are no t show n ~ ~ ~ _ _ _ _• Switch 3WoySwltch Wire Connector STlJPS o Use to switch light in one place e Supply power to switch using conductor with ground NM cable (14/2 with grQlillQ for 15-amp circuits and 12/2 with grQlillQ for 20-amp circuits; & use 120-volt circuit only) Supply power to light with same size NM cable Join neutrals in switch box with wire connectors (white wires) Join ~ in switch box with grounding connector and connect grounding wire to switch Connect one "hot" (black wire) to each screw on side of switch • Connect lighting fixture to other end of cable (TIP: Color-match w ires: black to black, white to white and ground to ground.) e o o o STACKED SWITCH (2-1 POLE SWITCHES) For illustration clarification, grounding conductors are not shown M -­ 2conductof w/ ground NMca ~ -~~ ~ STlJPS o Use to switch light in two places e Supply power to first switch using conductor with ground NM cable (14/2 with ground for 15-amp circuits and 12/2 with ground for 20-amp circuits; & use 120-volt circuit only) Supply power to light from second switch box with same size NM cable Connect switches together using conductor with ground NM cable (TIP: Use same wire size as power supply cables used in steps & 3.) Join neutrals in each switch box with wire connectors (white wires) Join ~ in each switch box with grounding connector and connect grounding wire to switch • Connect the "hot" (black wire) from the conductor with ground cable to each common screw on each 3-way switch (TIP: Common screw is usually black.) G Connect black and red wires from each conductor with ground cable to the gold screws on each 3-way switch (TIP: Either color wire may go on either gold screw.) Ci) Connect lighting fixture to other end of conductor with g[Q!.!!}Q cable (TIP: Co!or-match wires: black to black, white to white and 9!:Qill&!Q ground.) e o o o 3-way switches are requ ired by the National Electrical Code (NEC) at each level of the home where there are interior stairways with risers or more This requirement provides a way to turn on the lighting at each level to provide illumination of the stairway While thi s is the only requ ired locati on of 3-way switchin g, man y areas of the home can benefit from additional switch locations Study traffic patterns in the home to determine the most beneficial location for additional switches 4-WAY SWITCH STlJPS o Use to switch STBPS o Use to switch two lights in one place Supply power to switch using conductor with 9IQilllQ NM cable (14/2 with ground for 15-amp circuits and 12/2 with ground for 20-amp circuits ; & use 120-volt circuit only) Supply power to lights, with same size NM cable to each light Join all neutrals in switch box with wire connectors (white wires) Join all ~ in switch box with grounding connector and connect grounding wire to switch Connect "hot" (black wire) from power supply to gold screw on side of switch with jumper between terminals • Connect one "hot" (black wire) from each cable to lighting fixtures to each gold screw on opposite side of switch G Connect lighting fixtures to other end of cables (TIP: Color-match wires: black to black, white to white and ground to e o o o grQlillQ.) ,­ ­ .­ ,-­ .- " - ""­ For illustration clarification grounding conductors are not shown NM_ , , light in three "' "' "" or more places Supply power to first L-I.I - - - ~ ~-\-lf-~ \+_ J switch using conductor with ground NM cable (14/2 with grQlillQ for 15-amp circuits and 12/2 with ground for 20-amp circuits; & use 120-volt circuit only) Supply power to light from last switch box with same size NM cable Connect all switches together using conductor with gmynQ NM cable (TIP: Use same wire size as power supply cables used in steps & 3.) Join neutrals in each switch box with wire connectors (white wires) Join ~ in each switch box with grounding connector and connect grounding wire to switch • Wire first and last switch (as above for 3-way switches) G In the middle switch boxes, connect the red and black wires from one conductor with Q [Q.l.!.O.d cable to the terminals marked "input," and the red and black wires from the other conductor with ground cable to the terminals marked "output " Ci) Connect lighting fixture to other end of conductor with g[Q!.!!}Q cable e o o o USING SEPARATE SWITCHES FOR SWITCHING CEILING FAN WITH LIGHT KIT STIIPS o Use to switch light and fan separately in one location e Supply power to 2-gang switch box using conductor with 9.IQ.\J.ill! NM cable (14/2 with 9.IQ.\J.ill! for 15-amp circuits and 12/2 with 9IQ.l.!.O.Q for 20­ amp circuits; .& use 120-volt circuit only) Supply power to fan/light from switch box using same size conductor with ground NM cable Join neutrals in switch box with wire connectors (white wires) Join ~ in switch box with grounding connector and connect grounding wire to each switch Connect the "hot" (black wire) from the conductor with ground cable to one gold screw on each switch (TIP: Use two short black wires and wire connector ) Connect black and red wires from conductor with ground cable to one gold screw on each switch (TIP: Either wire may go on either switch.) Connect lighting fixture to other end of conductor with 9IQ.l.!.O.Q cable (TIP: Color-match wires: black to black, white to white and ground to ground; connect red wire to light kit - usually a blue wire, but will be identified.) f) .& ALWAYS use outlet box listed for fan support e o e o o POWER FED TO THE LIGHT STIIPS o Alternate method to switch light in one place (TIP: Used by many electricians, especially in older homes.) Supply power to light outlet box using conductor with 9.IQ.\J.ill! NM cable (14/2 with 9IQ.l.!.O.Q for 15-amp circuits and 12/2 with ground for 20-amp circuits; A use 120-volt circuit only) Supply power to switch from lighting outlet box using same size conductor with ground NM cable Connect white wire to one gold screw on switch and black wire to other gold screw on switch (TIP: Re-identify white wire with black tape or marker.) , Connect grounding wire to switch Connect black wire from power supply to white wire to switch box in lighting outlet box with wire connector (TIP: Re-identify white wire with black tape or marker.) Connect lighting fixture to remaining wires in lighting outlet box (TIP: Color-match wires: black to black, white to white and ground to ground.) e e o o • Smoke detectors must be installed in each sleeping room of a dwelling unit • Smoke detectors must be installed outside of each sleeping room of a dwelling unit • A single (1) smoke detector outside will suffice for multiple sleeping rooms (coverag e usually extends 40 ft.; see manufacturer's instructions included with smoke detector for more details) Smoke detectors must be installed on each level of a dwelling unit, including basements but not including crawl spaces or uninhabitable attics Smoke detectors must be hard wired and powered by an AFCI-protected circuit Smoke detectors must be interconnected so that if one detector is activated, the alarm on all detectors will sound DO NOT install smoke detectors within ft of HVAC vents or ceiling fans Smoke detectors are not normally recommended to be installed in kitchens or garages (possibility of false alarms) Smoke detectors installed on a wall must be located at least in from the ceiling and not more than 12 in below the ceiling Smoke detectors located on the ceiling must be installed at least in from the adjoining wall PEAKED CEILING Smoke detectors must be installed within 36 in horizontally of the peak, but not closer than in vertically to the peak TRAY CEILING Smoke detectors must be installed either on the wall at least in from the ceiling and not more than 12 in below the highest point of the ceiling or on the highest portion of the ceiling at least in from the adjoining wall 4" Smoke detectors must be installed within 36 in of the high side of the ceiling, but not 36'· closer than in from :;;;._ _ _ _~~~~~~~~~.J the adjoining wall GFCI-PROTECTED RECEPTACLE OUTLETS DUPLEX RECEPTACLE OUTLETS For illustration clarification, grounding conductors are not shown For illustration clarification, grounding conductors are not shown f\ Black wires to gold or brass screws White wires to silver screws f\ ( ondu(lor wI ground , NM cable SYMBOL =@ V Incomlng Powo< ~~ ©l conductor wI ground NM cabte To Remaining Oudet's onOrcuit 8lKk wirM to gold Of brass screws White wl res to sill/« SCrew! • Duplex receptacles are used throughout the home to supply power to appliances • Usually, power is supplied using conductor with grQY!}Q NM cable (TIP: Use 14/2 with lJfQllllQ for 15-amp circuits and 12/2 with ground for 20-amp circuits; & use 120-volt circuit only.) • Multiple receptacles may be connected on the same circuit The 2008 National Electrical Code (NEe) requires most receptacle outlets in homes to be tamper-resistant • Receptacles must be installed so that no point measured horizontally along the floor in any wall space is more than ft from a receptacle outlet in most habitable rooms Wall space is considered any space ft or more in width, measured around corners and unbroken by fireplaces, doors or similar openings Receptacle outlets in floors may be counted as those required receptacles, if placed within 18 in of the wall ft rule does not apply to unfinished basements, attached or detached garages, bathrooms, laundry rooms, hallways, kitchen countertops or closets • Receptacles must be installed so that no point measured horizontally along the kitchen countertop is more than ft from a receptacle outlet Kitchen countertop receptacles must be supplied by at least dedicated 20-amp branch circuits At least receptacle outlet must be installed within ft of each bathroom sink S'rIIPS o e e , o o • , & f\ V Black wires connect to gold screws White wires connect to silver screws Join grounds together and connect to green screw Use 20-amp circuits for bathrooms, kitchens, dining rooms and laundry rooms Several types of connections may be made Wrap wire around screw Push in terminals for 14 AWG wire Clamping mechanism on side terminals WARNINGI DO NOT remove too much insulation from wires I"","""" """" conductor wI grou nd SvMaOL' =@ NMClbie V l~ tiJl cor'KIuc:tor " w/groond NMu~ ~=n~~ V Generally required in arMS ~ w.m may be pteSeflt GFCI protection is required for 120-volt 15- and 20-amp receptacle outlets in the following locations of dwelling units: kitchen countertops bathrooms attached and detached garages unfinished basements crawl spaces outdoors • within ft of laundry, wet bar or utility sinks GFCI receptacles are used to minimize hazards from mixture of water and electricity One GFCI receptacle may protect downstream receptacles on the same circuit STIIPS o Connect incoming power supply to terminals marked "Line." (TIP: Black wire to gold screw, white wire to silver screw and bare ground to green screw.) • Connect other duplex receptacles downstream to terminals marked "Load." (TIP: GFCI protection will be provided for these receptacles as well.) PREPARING NM CABLES FOR TERMINATIONS R STIIPS o Remove outer sheathing from cable (TIP: Leave at least y." of sheathing on cable inside of box.) • Make a "V" with the grounds and grab with the end of lineman's pliers Twist pliers clockwise four or five times while pulling outward on the e ~ o If a crimp sleeve is used, cut off unneeded grounds and crimp connector to join grounds e If a wire connector is used, cut off unneeded grounds and join with wire connector • • 240-VOLT RECEPTACLE OUTLETS 240-volt receptacles are generally used for larger appliances such as clothes dryers and ranges (stoves) Usually, only one receptacle is installed on a circuit As a rule, power is supplied using conductor with ground NM cable or conductor SER cable ., Terminals may be marked "X" or "Y" for "hot" wires (TIP: Black or red may terminate on either.) • Terminals for neutrals (white wires) will usually be marked 'WI-I': "INhite" or "N" STIIPS o Use 10/3 with ground copper cables for 30-amp electric clothes dryer outlets e Use 6/3 with lJfQllllQ copper cables for 50-amp electric range outlets Grounding conductor may be green or bare ~ BASIC GROUNDING REQUIREMENTS Z Vd = Voltage Drop (in volts, not use percentage) III I = Current of Circuit (use actual current draw of circuit, not circuit size) W L = One-Way Length of Circuit (distance from source of power to load served) ~ Cmil = Cross-Sectional Area of Conductor (see table below) K = Resistance of Conductor per Circular Mil for Each Foot of Conductor o ~ Sheet metal screws or solder not allowed for connection of grounding devices • Aluminum conductors are not allowed to be terminated outside within 18 in of the earth Main bonding jumper must be installed in the service equipment • Ground rods must be driven flush with grade , with at least ft in contact with the earth Means must be provided outside of service equipment for bonding of other systems (telephone, cable TV, satellite systems) • Grounding conductors must be bare or have green insulation (use of green tape only allowed for grounding conductors larger than #6 AWG) *K factor for Copper = 12 *K factor for Aluminum = 21.2 SINGLE PHASE Vd = 2x Kx LxI Cmil OR Cmil = x K x L x I Vd THREE PHASE Vd= 1.732xKxLxl Cmil OR Cmil = 1.732 x K x L x I Vd l ~ #14 #12 #10 #8 #6 4110 6530 10380 16510 26240 41740 52620 66360 83690 105600 133100 167800 211600 #4 #3 #2 #1 1/0 2/0 3/0 4/0 .& 21 O.19(A)(1) FPN NO.4 suggests a I maximum 3% voltage drop for individual circuit and feeder I conductors, and a maximum 5% overall voltage drop for the entire circuit TIP: The circular mil I area of conductors larger than 4/0 is I simply the size of I the conductor (EX: 250 kcmil = 250,000 circular mils) EQUIPMENT GROUNDING CONDUCTORS I Equipment grounding conductors are used to ground all equipment on the load side of the service equipment They must be sized according to Table 250.122 of the NEC • Equipment grounding conductor sizes are based on the rating of the overcurrent device protecting the circuit • These grounding conductors must be routed with the other conductors of the circuit and, with few exceptions, must be contained in the same raceway or cable assembly • Most cable assemblies contain bare or insulated equipment grounding conductors that are properly sized for the maximum circuit rating that the cable is allowed I EX: What is the voltage dropped in a 120-volt circuit that is 250 ft long, using #12 copper conductors and supplying a load with a current draw of 14 amps? ~ Z Voltage drop = x 12.9 x 250 x 14 6,530 To find percentage of voltage drop: 13.8 = Voltage Drop x 100 Circuit Supply Voltage 120 W% ~ o p~ • 90 ,300 = 13.8 volts 6,530 EX: A 20-amp circuit would require a #12 copper equipment grounding conductor for grounding of all equipment on that circuit 115 x 100 = 11 5% This would be an excessive loss of voltage and the conductor sizes would need to be increased to compensate To calculate the necessary wire size before wiring the circuit, use the following: Sizing Grounding Conductors (based on Table 250.122) Circuit Breaker or Fuse Size Ground Wire Size (in Amps) Copper Aluminum What minimum size copper conductors would be needed to prevent a voltage drop in excess of 3% for a 120-volt circuit that is 250 ft long with a current draw of 14 amps? Cmils=2xKxLxl = 2x12.9x250x14 Voltage Drop* 3.6 90.300 25,083.3 cmils* = #6 copper 3.6 • • #14 #12 #10 #8 #6 15 20 30-60 70-100 110-200 225-300 #12 #10 #8 #6 #4 #2 #4 GROUNDING ELECTRODE CONDUCTORS Grounding electrode conductors are used to connect all portions of the grounding electrode system together on the supply side of the service equipment These conductors are required to be connected to ground rods , rebar in footers and foundations , and metallic water piping, with at least 10ft in contact with the earth where they are present at each building They must be connected to the service equipment and their sizing is based on Table 250.66 of the NEC, with a few exceptions Unlike equipment grounding conductors, grounding electrode conductors are sized on the basis of the size of the ungrounded service entrance conductors Grounding electrode conductors are used to quickly take excessive voltage spikes caused by lightning strikes or power surges to the ground and also serve to stabilize the normal voltage to ground ~ Z W EX: ~ For a service supplied with 3/0 copper service entrance conductors, a #4 copper grounding electrode conductor is required for connection to the metallic water piping system o ~ TIP: Grounding electrode conductors routed directly to ground rods are never required to be larger than #6 copper (Local rules may require larger.) .& A properly installed grounding system is essential to a safe electrical system Some of the purposes for grounding include: limiting voltages caused by lightning, stabilizing the voltage under normal operating conditions, and ensuring the facilitation of overcurrent devices under ground fault conditions Grounding at Services (based on Table 250 66) Size of Service Conductors AL Size of Grounding Electrode Conductors CU AL #2 or smaller 1/0 or smaller #8 #1-1 /0 2/0-3/0 #6 2/0-3/0 4/0-250 #4 4/0-350 #2 300-500 400-600 600-900 1/0 700-1100 1000-1 750 2/0 1750+ 1100+ 3/0 #6 #4 #2 CU - 1/0 r I I I 3/0 I 4/0 I I _ 250 BASIC REQUIREMENTS FOR PANELBOARDS · Connectors M U S.I be used to Supply subpanels with four conductors (TIP: Two "hots" [black or red], one neutral [white] and one ground [green or bare].) Isolate grounds (green or bare) and neutrals (white wires) at subpanels Only install one neutral (white wire) or one "hot" (black or red wire) under each terminal Bond ground bar to panel enclosure .6 DO NOT bond neutral bar to panel enclosure Main breaker is not required for subpanels if proper breaker is used for supply of the subpanel (EX: Supply a 1~O-amp subpanel with a breaker that is not rated over 100 amps.) • Multiple grounds may be installed under the same terminal if they are the same size and material Aluminum and copper conductors may never be mixed under the same terminal .& ALWAYS use separate terminals for aluminum and copper White insulated wires, in cable assemblies, used as "hots" M.!J S.I be re-identified at the termination points with black tape or black color markings 80 Maintain clear work space around all electrical panels & Nf.'lf.B use space in front of panels for storage 88 DO NOT install panels in clothes closets or bathrooms 88 & DO NOT overload service equipment! (Call a licensed electrician if you are unsure of the load requirements.) protect cables entering panels · Fill in all unused holes in panels to prevent accidental contact with live parts • Use proper closure plates and plugs .& WARNINGI DO NOT use duct tape • Only use correct breaker types for panels (EX: GE breakers in GE panels only; Siemens breakers in Siemens panels only; etc.) Label panels correctly after installing new circuits or doing renovations The 2008 National Electrical Code (NEe) requires most circuits in homes to be protected by an Arc­ Fault-Circuit-Interrupter circuit breaker wi ground Copper NM e o e e o wi ground Copper NM #1212 Refrigeratorl Freezer wi ground X CopperNM X #1 212 wi ground Copper NM #1412 #1212 wi ground CopperNM wi ground #1412 #1212 wi ground Copper NM wi ground Copper NM CopperNM X X X X X X X X Oven! #1013 1/813 Cooktop wi ground w/ground CopperNM X X CopperNM l/616l6I8 ALSER Free Standing Range X X X Heater Clothes Dryer Hydromassage Tub l U.S $5.95 X X X X X #1212 wi ground CopperNM #4141416 ALSER wi ground CopperNM #8161618 #4141416 X X X wi ground CopperNM #1013 wi ground Copper NM X [NOTE: This table is used for service entrance conductors and feeders if the feeder supplies the entire load of dwelling unit.] CopperNM wi ground CopperNM #10/2 SERVICE & FEEDER CONDUCTOR SIZES FOR DWELLING UNITS 1/813 wi ground #813 ALSER X X X CIRCUIT BREAKER & CABLE SIZES FOR SMALL CIRCUITS 15 #14 20 #12 25 #10 30 #10 35 #2 #4 #8 #8 #6 #1 #3 40 #8 #8 #6 125 1/0 #2 45 #6 #6 #4 150 2/0 #1 50 #6 #6 #4 110 175 3/0 1/0 200 4/0 2/0 225 250 3/0 250 300 4/0 300 350 250 350 500 350 400 600 400 Table is ba sed on excerpts from 240.6, Table 310.16 240.4(0 ) and 334.80 (assumlng II terminal provisions are listed fer 75 degrees C.) AUTHOR: Ch ris Prince; James Da niel Sa ndefur, SME ISBN-13 : 978-142320889-1 ISBN-10 : 142320889-7 DISCLAIMER: Thi s guide is intended for informational purposes only Due to its conde nsed format, it cannot possibly cover every aspect of the subject and should not be used as a substitute for advice from a licen sed electrician BarCha rts , Inc its writers, editors and designers are not responsible or liable for the use or misuse of the information contai ned in this guide o ~ X X X #813 ALSER Water X CONDUCTOR & CABLE SIZES FOR TYPICAL HOUSEHOLD CIRCUITS A ll righls reserved No part of this publicfltion may be rep rod uced or transmItted in any form or by any means, electronic or mcc h,m ical including photocopy record mg , or any information storage and retrieval system without writtfln permissi on from the publisher it2009 Ba rC harts, Inc 1209 ~m~ ~lllWlj I rl l 1rl ll~ Customer Hotline # 1.800.230.9522 free downloads & hun d\l3.dS,pf titlils at QUICKS1:Uay.com ,tlLUJ