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City Electric Supply’s Electrical References

Ampacity Chart
Ampere Formula Calculator
NEC Conduit Fill
Foot Candle Recommendations
Kelvin Chart
Lamp Mounting Height Guide
NEMA & UL Ratings

Ampacity Chart


Amperage is a measure of the electrical current flowing through a circuit. Current is measured in amperes (amps). You must use the correct size wire for the amperage requirement of the circuit to prevent the wire from overheating.

The number and type of electrical devices connected to a circuit determine the amperage requirement of the circuit. Usually, a general purpose house circuit is designed for 20 amps. Lighting circuits may be designed for only 15 amps.

To calculate the amperage for a circuit, first add up the wattage of all the electrical devices that will be on the circuit. Then divide the total wattage by the voltage of the system, 110 or 220, and that will give you the expected current or amps.

Wire Size and Amp Ratings Below


Copper Aluminum
60˚C
(140˚F)
75˚C
(167˚F)
90˚C
(194˚F)
75˚C
(167˚F)
90˚C
(194˚F)
NM-B THW THWN-2 THW XHHW-2
UF-B THWN THHN THWN THHN
--- SE XHHW-2 SE TWHN-2
--- USE --- USE ---
--- XHHW --- XHHW ---

Wire Gauge Size Copper Aluminum
14 15 15 15 --- ---
12 20 20 20 15 15
10 30 30 30 25 25
8 40 50 55 40 45
6 55 65 75 50 60
4 70 85 95 65 75
3 85 100 110 75 85
2 95 115 130 90 100
1 --- 130 150 100 115
1/0 --- 150 170 120 135
2/0 --- 175 195 135 150
3/0 --- 200 225 155 175
4/0 --- 230 260 180 205
250 --- 255 290 205 230
300 --- 285 320 230 255
500 --- 380 430 310 350
600 --- 420 475 340 385
750 --- 475 535 385 435
1000 --- 545 615 445 500
Print Copy

Ampere Formula Calculator


Print Copy
Voltage or volts E or V =
Amperage or current I =
Resistivity or resistance R =
Wattage or power P =
For R take impedance Z

NEC Conduit Fill

TW, XHHQ (14 thru 8)

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
14 9 15 25 44 60 99 142
12 7 12 19 35 47 78 111
10 5 9 15 26 36 60 85 131 176
8 2 4 7 12 17 28 40 62 84 108

RHW and RHH (Without Outer Covering) THW

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
14 6 10 16 29 40 65 93 132 192
12 4 8 13 24 32 53 76 117 157
10 4 6 11 19 26 43 61 95 127 163
8 1 3 5 10 13 22 32 49 66 85 133

TW, THW, FEPB (6 thru 2) RWH & RHH (without outer covering)

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
6 1 2 4 7 10 16 23 36 48 62 97 141
4 1 1 3 5 7 12 17 27 36 47 73 106
3 1 1 2 4 6 10 15 23 31 40 63 91
2 1 1 2 4 5 9 13 20 27 34 54 78
1 - 1 1 3 4 6 9 14 19 25 39 57

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
0 - 1 1 2 3 5 8 12 16 21 33 49
00 - 1 1 1 3 5 7 10 14 18 29 41
000 - 1 1 1 2 4 6 9 12 15 24 35
0000 - - 1 1 1 3 5 7 10 13 20 39

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
250 - - 1 1 1 2 4 6 8 10 16 23
300 - - - 1 - 2 4 6 8 10 16 23
350 - - - 1 1 1 3 4 6 8 12 18
400 - - - 1 1 1 2 4 5 7 11 16
500 - - - 1 1 1 1 3 4 6 9 14

-
Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
600 - - - - 1 1 1 3 4 5 7 11
700 - - - 1 1 1 2 3 4 7 10
750 - - - - 1 1 1 2 3 4 6 9

XHHW

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
6 1 3 5 9 13 21 30 47 63 81 128 183
600 - - 1 1 1 1 1 3 4 5 9 13
700 - - - 1 1 1 1 3 4 5 7 11
750 - - - 1 1 1 1 2 3 4 7 10

Foot Candle Recommendations


Print Copy
TASK AREA FOOTCANDLES
Corridors/Stairways/Restrooms 10-20
Storage Rooms 10-50
Conference Rooms 20-50
General Offices 50-100
Drafting/Accounting 100-200
Areas with VDTs 75
Classrooms 50-75
Cafeterias 50
Gymnasiums 30-50
Merchandising 30-150
Manufacturing/Assembly 50-500
Parking Areas (uncovered) 1-2
General Building Construction 10
Airports  
Hangar Aprons 1
Terminal Apron-Parking 0.5
Bulletin Boards  
Light Surfaces 20/50
Dark Surfaces 50/100
Loading Platforms 20
Parking Areas/Vehicular Traffic  
Low Activity 0.5
Medium Activity 1
High Activity 2
Railroad Yards  
Switch Points 2
Shipyards  
General 5
Storage Yards 201
Sports  
Baseball-Recreational 15/10
Basketball - High School 30
Basketball - Recreational 10
Playgrounds 5
Tennis 20
Print Copy

Kelvin Temperature Chart


Print Copy
Degrees Kelvin Type of Light Source Indoor (3200k) Color Balance Outdoor (5500k) Color Balance
1700-1800K Match Flame    
1850-1930K Candle Flame    
2000-3000K Sun: At Sunrise or Sunset    
2500-2900K Household Tungsten Bulbs    
3000K Tungsten lamp 500W - 1K    
32000 - 3500K Quartz Lights    
32000 - 7500K Fluorescent Lights    
3275K Tungsten Lamp 2k    
3380K Tungsten Lamp 5k, 10K    
5000 - 5400K Sun: Direct at Noon    
5500 - 6500K Daylight (Sun + Sky)    
5500 - 6500K Sun: through clouds/haze    
6000 - 7500K Sky: Overcast    
6500K RGB Monitor(White Pt.)    
7000 - 8000K Outdoor Shade Areas    
8000 - 1000K Sky: Partly Cloudy    
Print Copy

Lamp Mounting Height Guide


Watts H.P. Sodium Metal Halide Mercury Tungsten Halogen
70 10-15'
100 10-20'
150 20-25'
175 18-23'
200 20-25'
250 20-27' 20-25' 20-25'
400 30-35' 25-30' 20-25'
500 15-20'
1000 40-50' 40-45' 35-40' 20-25'
1500 25-30'

NEMA & UL Ratings


NEMA & UL are standard writing organizations commonly recognized in the North American continent. The following ratings are based on similar application descriptions and expected performance. UL requires enclosure testing by qualified evaluators. The Milbank Test Lab is certified in the UL Client Test Data Program. They also send site inspectors to check manufacturer adherence to prescribed manufacturing methods and material specifications. NEMA does not require independent testing, which leaves compliance totally up to the manufacturer.

NEMA National Electrical Manufacturers Association (NEMA Standard 250)


Type 1

Enclosures are intended for indoor use primarily to provide a degree of protection against limited amounts of falling dirt. (NEMA Standard 7·15·1991)

Type 3

Enclosures are intended for outdoor use primarily to provide a degree of protection against rain, sleet, windblown, dust and damage from external ice formation. (NEMA Standard 7·15·1991)

Type 3R

Enclosures are intended for outdoor use primarily to provide a degree of protection against rain, sleet and damage from external ice formation. (NEMA Standard 7-15-1991)

Type 4

Enclosures are intended for indoor and outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water and damage from externally formation. (NEMA Standard 1-10-1979)

Type 4X

Enclosures are intended for indoor and outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water and damage from external ice formation. (NEMA Standard 1-lG-1979)

Type 12

Enclosures are intended for indoor use primarily to provide a degree of protection against circulating dust, falling dirt and dripping noncorrosive liquids. (NEMA Standard 7-15-1991)

Type 13

Enclosures are intended for indoor use primarily to provide a degree of protection against dust, spraying of water, oil and noncorrosive coolant.

Disclaimers

The definitions on this page are reproduced with permission from NEMA. These descriptions are not Intended to be complete representations of National Electrical Manufacturers Association standards.

Ampacity Chart
Copper Aluminum
60˚C
(140˚F)
75˚C
(167˚F)
90˚C
(194˚F)
75˚C
(167˚F)
90˚C
(194˚F)
NM-B THW THWN-2 THW XHHW-2
UF-B THWN THHN THWN THHN
--- SE XHHW-2 SE TWHN-2
--- USE --- USE ---
--- XHHW --- XHHW ---

Wire Gauge Size Copper Aluminum
14 15 15 15 --- ---
12 20 20 20 15 15
10 30 30 30 25 25
8 40 50 55 40 45
6 55 65 75 50 60
4 70 85 95 65 75
3 85 100 110 75 85
2 95 115 130 90 100
1 --- 130 150 100 115
1/0 --- 150 170 120 135
2/0 --- 175 195 135 150
3/0 --- 200 225 155 175
4/0 --- 230 260 180 205
250 --- 255 290 205 230
300 --- 285 320 230 255
500 --- 380 430 310 350
600 --- 420 475 340 385
750 --- 475 535 385 435
1000 --- 545 615 445 500
Ampere Formula Calculator
NEC Conduit Fill

TW, XHHQ (14 thru 8)

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
14 9 15 25 44 60 99 142
12 7 12 19 35 47 78 111 171
10 5 9 15 26 36 60 85 131 176
8 2 4 7 12 17 28 40 62 84 108

RHW and RHH (Without Outer Covering) THW

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
14 6 10 16 29 40 65 93 132 192
12 4 8 13 24 32 53 76 117 157
10 4 6 11 19 26 43 61 95 127 163
8 1 3 5 10 13 22 32 49 66 85 133

TW, THW, FEPB (6 thru 2) RWH & RHH (without outer covering)

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 3 31/2 4 5 6
6 1 2 4 7 10 16 23 36 48 62 97 141
4 1 1 3 5 7 12 17 27 36 47 73 106
3 1 1 2 4 6 10 15 23 31 40 63 91
2 1 1 2 4 5 9 13 20 27 34 54 78
1 - 1 1 3 4 6 9 14 19 25 39 57
Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
0 - 1 1 2 3 5 8 12 16 21 33 49
00 - 1 1 1 3 5 7 10 14 18 29 41
000 - 1 1 1 2 4 6 9 12 15 24 35
0000 - - 1 1 1 3 5 7 10 13 20 39
Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
250 - - 1 1 1 2 4 6 8 10 16 23
300 - - - 1 - 2 4 6 8 10 16 23
350 - - - 1 1 1 3 4 6 8 12 18
400 - - - 1 1 1 2 4 5 7 11 16
500 - - - 1 1 1 1 3 4 6 9 14
Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
600 - - - - 1 1 1 3 4 5 7 11
700 - - - - 1 1 1 2 3 4 7 10
750 - - - - 1 1 1 2 3 4 6 9

XHHW

Conductor Size AWG MCM Conduit Size (Inches) 1/2 - 6
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4 5 6
6 1 3 5 9 13 21 30 47 63 81 128 183
600 - - 1 1 1 1 1 3 4 5 9 13
700 - - - 1 1 1 1 3 4 5 7 11
750 - - - 1 1 1 1 2 3 4 7 10
Foot Candle Recommendations
TASK AREA FOOTCANDLES
Corridors/Stairways/Restrooms 10-20
Storage Rooms 10-50
Conference Rooms 20-50
General Offices 50-100
Drafting/Accounting 100-200
Areas with VDTs 75
Classrooms 50-75
Cafeterias 50
Gymnasiums 30-50
Merchandising 30-150
Manufacting / Assembly 50-500
Parking Areas (uncovered) 1-2
General Building Construction 10
Airports  
Hangar Aprons 1
Terminal Apron-Parking 0.5
Bulletin Boards  
Light Surfaces 20/50
Dark Surfaces 50/100
Loading Platforms 20
Parking Areas/Vehicular Traffic  
Low Activity 0.5
Medium Activity 1
High Activity 2
Railroad Yards  
Switch Points 2
Shipyards  
General 5
Storage Yards 201
Sports  
Baseball-Recreational 15/10
Basketball - High School 30
Basketball - Recreational 10
Playgrounds 5
Tennis 20
Kelvin Chart
Degrees Kelvin Type of Light Source Indoor (3200k) Color Balance Outdoor (5500k) Color Balance
1700-1800K Match Flame    
1850-1930K Candle Flame    
2000-3000K Sun: At Sunrise or Sunset    
2500-2900K Household Tungsten Bulbs    
3000K Tungsten lamp 500W - 1K    
32000 - 3500K Quartz Lights    
32000 - 7500K Fluorescent Lights    
3275K Tungsten Lamp 2k    
3380K Tungsten Lamp 5k, 10K    
5000 - 5400K Sun: Direct at Noon    
5500 - 6500K Daylight (Sun + Sky)    
5500 - 6500K Sun: through clouds/haze    
6000 - 7500K Sky: Overcast    
6500K RGB Monitor(White Pt.)    
7000 - 8000K Outdoor Shade Areas    
8000 - 1000K Sky: Partly Cloudy    
Lamp Mounting Height Guide
Watts H.P. Sodium Metal Halide Mercury Tungsten Halogen
70 10-15'
100 10-20'
150 20-25'
175 18-23'
200 20-25'
250 20-27' 20-25' 20-25'
400 30-35' 25-30' 20-25'
500 15-20'
1000 40-50' 40-45' 35-40' 20-25'
1500 25-30'
NEMA & UL Ratings
Type 1

Enclosures are intended for indoor use primarily to provide a degree of protection against limited amounts of falling dirt. (NEMA Standard 7·15·1991)

Type 3

Enclosures are intended for outdoor use primarily to provide a degree of protection against rain, sleet, windblown dust and damage from external ice formation. (NEMA Standard 7·15·1991)

Type 3R

Enclosures are intended for outdoor use primarily to provide a degree of protection against rain, sleet and damage from external ice formation. (NEMA Standard 7-15-1991)

Type 4

Enclosures are intended for indoor and outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, hose-directed water and damage from external formation. (NEMA Standard 1-10-1979)

Type 4X

Enclosures are intended for indoor and outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, hose-directed water and damage from external ice formation. (NEMA Standard 1-lG-1979)

Type 12

Enclosures are intended for indoor use primarily to provide a degree of protection against circulating dust, falling dirt and dripping noncorrosive liquids. (NEMA Standard 7-15-1991)

Type 13

Enclosures are intended for indoor use primarily to provide a degree of protection against dust, spraying of water, oil and noncorrosive coolant.

Disclaimers

The definitions on this page are reproduced with permission from NEMA. These descriptions are not intended to be complete representations of National Electrical Manufacturers Association standards.