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                   (prior doing business as KR Services) 
 

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EQUIPMENT SELECTION AND OPTIMIZATION SOFTWARE 

Wire size chart 
Square D Co., 1978
* Type THW, THWR, XHHW SINGLE CONDUCTOR IN CONDUIT
(Note by KR: This is NOT a "Romex" chart)

Size

Copper*

Aluminum*

18

5

-

16

10

-

14

15

-

12

20

15

10

30

25

8

45

40

6

65

50

4

85

65

3

100

75

2

115

90

1

130

100

O

150

120

OO

175

135

OOO

200

155

OOOO

230

180

250

255

205

300

285

230

350

310

250

400

335

270

500

380

310

600

420

340

700

460

375

750

475

385

Temperature Capacity Correction Factors:

For Ambient
Degrees F

Multiply
current by:

86

1

94

0.94

104

0.88

113

0.82

122

0.75

131

0.67

140

0.58

158

0.35

167

Not Allowed
 

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