the first step in recording information on an electrical panel is to list the circuits according to...

The first step in recording information on an The first step in recording information on an electrical panel is to list the circuits according to electrical panel is to list the circuits according to the plan, realizing that each slot in the panel is the plan, realizing that each slot in the panel is good for ONE phase wire. Since all lighting and good for ONE phase wire. Since all lighting and convenience outlets are single phase, or single convenience outlets are single phase, or single pole, then one slot is sufficient for each 20 amp pole, then one slot is sufficient for each 20 amp circuit.circuit.

Special outlets, generally are to remain as Special outlets, generally are to remain as single circuits. As you list a special outlet, it is single circuits. As you list a special outlet, it is essential to know if the outlet device is single pole, essential to know if the outlet device is single pole, two pole, or three pole, as each pole represents a two pole, or three pole, as each pole represents a phase wire. So a two pole outlet requires two phase wire. So a two pole outlet requires two numbered slots in the panel, and three pole outlets numbered slots in the panel, and three pole outlets require three. require three.

Remember there are three elements in each Remember there are three elements in each of the electrical formulas; amperes, watts, and of the electrical formulas; amperes, watts, and volts. So the designer must know at least two of volts. So the designer must know at least two of the elements in order to design a circuit for the the elements in order to design a circuit for the device. It is insufficient to say that a device is rated device. It is insufficient to say that a device is rated at so many amps, or so many volts, or so many at so many amps, or so many volts, or so many watts. It takes two elements to define the watts. It takes two elements to define the electrical requirements for a device. electrical requirements for a device.

ProjectPhasevoltsDate

PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights

convenienceoutletsconvenienceoutletsconvenienceoutletsconvenienceoutletsconvenienceoutlets


201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1

15 exhaust fanmotor 1/2 hp

AC fan motor1 hp

215 230 electric

water heater6 kw

3air conditioningcompressor26 amperes

30

The next step is to assign wattage to each of The next step is to assign wattage to each of the phase wires in the panel. Each phase wire is to the phase wires in the panel. Each phase wire is to be loaded with the single pole wattage of a circuit be loaded with the single pole wattage of a circuit plus the single pole wattage of the circuit that is on plus the single pole wattage of the circuit that is on the opposite side of the panel. For instance, phase the opposite side of the panel. For instance, phase wire A will be loaded with watts from circuit ONE wire A will be loaded with watts from circuit ONE and TWO; phase wire B will be loaded with watts and TWO; phase wire B will be loaded with watts from circuits THREE and FOUR; phase wire C will be from circuits THREE and FOUR; phase wire C will be loaded with watts from circuits FIVE and SIX, and loaded with watts from circuits FIVE and SIX, and so on.so on.

Since special outlets are circuits by Since special outlets are circuits by themselves, the wattage of the device is divided themselves, the wattage of the device is divided equally between phase wires. For instance in this equally between phase wires. For instance in this example the circuit for the AC fan motor is two example the circuit for the AC fan motor is two pole, so the wattage of the fan will be divided pole, so the wattage of the fan will be divided between the next two panel phase wires in the between the next two panel phase wires in the progression. Likewise, the AC compressor is three progression. Likewise, the AC compressor is three pole, so the wattage of the compressor is divided pole, so the wattage of the compressor is divided equally between all three phase wires. equally between all three phase wires.

The following series of slides shows the The following series of slides shows the progression of circuit wattage as they are assigned progression of circuit wattage as they are assigned to the panel phase wires.to the panel phase wires.


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920

19201920

19201920

1920 9.8 x 120 = 1176 watts1176


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920

19201920

19201920

1920 9.8 x 120 = 1176 watts1176

230v 1hp motor = 8 amps8 x 230 = 1840 watts1840 / 2 = 920 w/pole

920

920


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920

19201920

19201920

1920 9.8 x 120 = 1176 watts1176


920

9206000 w / 2 =3000 w per pole

3000

3000


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920

19201920

19201920

1920 9.8 x 120 = 1176 watts1176


920

9206000 w / 2 =3000 w per pole

3000

3000

26 a x 415.69 = 10,800 w10,800 / 3 = 3603 w/pole

3603

3603

3603

Your plan shows circuits A-17, A-18, and A-19. Your plan shows circuits A-17, A-18, and A-19. You were told at the beginning that would You were told at the beginning that would change. change. From the panel diagram, since the 2-From the panel diagram, since the 2-pole and 3-pole outlets must have multiple slots, pole and 3-pole outlets must have multiple slots, the proper designation for the above circuits the proper designation for the above circuits should be:should be:

A-17 is properly A-17,19A-17 is properly A-17,19A-18 is properly A-18,20A-18 is properly A-18,20A-19 is properly A-21,23,25A-19 is properly A-21,23,25

After all the circuits are listed and the After all the circuits are listed and the wattage is shown, add the columns of wattage wattage is shown, add the columns of wattage for each panel phase wire and record the total at for each panel phase wire and record the total at the bottom of each column.the bottom of each column.

Then add the three totals to find the total Then add the three totals to find the total wattage of the panel from the circuits. Then we wattage of the panel from the circuits. Then we will divide the wattage into three categories; will divide the wattage into three categories; continuous use wattage; wattage for convenience continuous use wattage; wattage for convenience outlets; and wattage for power equipment.outlets; and wattage for power equipment.


PANEL

3

slotno

1

5

7

circuit use

11

9

13

17

15

19

wattsline A

wattsline B line C

watts circuit use

4

noslot

2

6

8

12

10

14

18

16

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

120/240 3

A

lights

lights

lights

lights

lights



201

201

201

201

201

201

201

201

201

201

201

201

201

201

201 1


AC fan motor1 hp

215 230 electric

water heater6 kw


30

16001600

17001500

14001920

19201920

19201920

19201920

19201920

1920 9.8 x 120 = 1176 watts1176


920

9206000 w / 2 =3000 w per pole

3000

3000

26 a x 415.69 = 10,800 w10,800 / 3 = 3603 w/pole

3603

3603

3603

18,403 13,690 14,683

total = 46,776 watts

The remainder of the calculation for the The remainder of the calculation for the panel occurs at the bottom of the panel diagram, panel occurs at the bottom of the panel diagram, so for clarity, only the bottom of the chart is so for clarity, only the bottom of the chart is shown next . . .shown next . . .

17

19

18

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

KVA

total KVA

AC fan motor1 hp

215 230 electric

water heater6 kw


30

9203000

30003603

3603

3603

18,403 13,690 14,683


The National Electric code requires that The National Electric code requires that CONTINUOUS use wattage be increased by 25%, which CONTINUOUS use wattage be increased by 25%, which in this case continuous use wattage refers to the in this case continuous use wattage refers to the lighting. So we take the lighting circuits and total the lighting. So we take the lighting circuits and total the wattage;wattage;

Lighting: 1600 + 1600 + 1700 + 1500 + 1400 = 7800 Lighting: 1600 + 1600 + 1700 + 1500 + 1400 = 7800 wattswattsLighting load is 7800 x 1.25 = Lighting load is 7800 x 1.25 = 9750 watts9750 watts

Receptacles are the convenience outlets wattage Receptacles are the convenience outlets wattage amounts to circuits 6 through 15, which is 10 circuits:amounts to circuits 6 through 15, which is 10 circuits:

Receptacles : 1920 x 10 = 19,200 watts Receptacle Receptacles : 1920 x 10 = 19,200 watts Receptacle load can be decreased by 50% for all over 10,000 load can be decreased by 50% for all over 10,000 watts, since it is not likely that receptacles are used at watts, since it is not likely that receptacles are used at the same time.the same time.

Receptacles load = 10,000 + .5 ( 9200 ) = Receptacles load = 10,000 + .5 ( 9200 ) = 14,600 14,600 wattswatts

Equipment load is what is left:Equipment load is what is left:46,776 – 7800 – 19,200 = 46,776 – 7800 – 19,200 = 19,776 watts19,776 watts

17

19

18

20

21

23

25

27

lighting

equipment

receptacles

22

24

26

28

50%

demand

125%

100%

AC fan motor1 hp

215 230 electric

water heater6 kw


30

920

9203000

30003603

3603

3603

18,403 13,690 14,683


7,800

19,200

19,776

9,750

14,600

19,776

44,126

The total panel wattage equals 44,126. This The total panel wattage equals 44,126. This is the wattage for which the amperage is is the wattage for which the amperage is calculated, the wire and conduit size is found, and calculated, the wire and conduit size is found, and the size of the ground wire.the size of the ground wire.

Formula 3, since the panel is 3 pole, 3 phase, Formula 3, since the panel is 3 pole, 3 phase, 120/240 volt120/240 volt

Amperage = watts/1.732 x volts = 44,126 / 415.69Amperage = watts/1.732 x volts = 44,126 / 415.69Total amps = 106Total amps = 106

Main Breaker = 110 ampsMain Breaker = 110 amps

From wire size chart; wire = four # 2From wire size chart; wire = four # 2

Conduit size = 1 ¼”Conduit size = 1 ¼”

Ground wire = # 8Ground wire = # 8

This example problem is a small building. This example problem is a small building. Many buildings such as schools, hospitals, retail Many buildings such as schools, hospitals, retail stores, offices, and such will be large enough to stores, offices, and such will be large enough to require numerous panels.require numerous panels.

Each panel in a large installation will Each panel in a large installation will become a circuit from a main switchboard. become a circuit from a main switchboard.

As an illustration the next 3 slides is of a As an illustration the next 3 slides is of a real project that was built in New Braunfels, real project that was built in New Braunfels, Texas.Texas.

END OF DAY 16END OF DAY 16

And end of Electrical DesignAnd end of Electrical Design

the first step in recording information on an electrical panel is to list the circuits according to...

Documents

single pole wattage

total panel wattage

total wattage

wattage lighting

panel phase wires

columns of wattage

pole outlets

progression of circuit