Chapter 3 Wiring Methods and Materials
Chapter 3 Wiring Methods and Materials
Chapter 3 Wiring Methods and Materials
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310.60 ARTICLE 310 - CONDUCTORS FOR GENERAL WIRING<br />
(D) Engineering Supervision. Under engineering supervision,<br />
conductor ampacities shall be permitted to be calculated<br />
by means of the following general formula:<br />
Table 310.68 Ampaclties of Insulated Single Aluminum<br />
Conductor Cables liiplexed in Air Based on Conductor<br />
Temperatures of 90°C (194°F) <strong>and</strong> 105°C (221°F) <strong>and</strong><br />
Ambient Air Temperature of 40°C (104°F)<br />
1= TC-(TA+JiTD) Temperature Rating of Conductor [See Table<br />
RDC(l+YC)RCA<br />
~MlR·]<br />
2ool-S000 Volts<br />
Ampacity<br />
Sool-3S,OOO Volts<br />
Ampacity<br />
where:<br />
TC = conductor temperature in °C<br />
Conductor lOSoC lOSoC<br />
Size lJOoC (221°F) lJOoC (221°F)<br />
TA = ambient temperature in °C (AWG (194°F) Type (194°F) Type<br />
CiTD = dielectric loss temperature rise or kcmil) Type MV-90 MV-lOS Type MV-lJO MV-lOS<br />
RDC = dc resistance of conductor at temperature TC<br />
8 50 57<br />
YC = component ac resistance resulting from skin 6 70 77 75 84<br />
effect <strong>and</strong> proximity effect<br />
4 90 100 100 110<br />
2 125 135 130 150<br />
RCA = effective thermal resistance between conductor 1 145 160 150 175<br />
<strong>and</strong> surrounding ambient<br />
1/0 170 185 175 200<br />
2/0 195 215 200 230<br />
FPN: See Annex B for examples of formula applications. 3/0 225 250 230 265<br />
4/0 265 290 270 305<br />
250 295 325 300 335<br />
Table 310.67 Ampacities of Insulated Single Copper<br />
350 365 405 370 415<br />
500 460 510 460 515<br />
Conductor Cables liiplexed in Air Based on Conductor 750 600 665 590 660<br />
Temperatures of 90°C (194°F) <strong>and</strong> 105°C (221°F) <strong>and</strong> 1000 715 800 700 780<br />
Ambient Air Temperature of 40°C (104°F)<br />
_.]<br />
Temperature Rating of Conductor [See Table<br />
2ool-S000 Volts<br />
Ampacity<br />
Sool-3S,OOO Volts<br />
Ampacity<br />
Conductor lOSOC lOSOC<br />
Size 90°C (22l"F) 90°C (221°F)<br />
(AWG (194°F) Type (194°F) Type<br />
or kcmil) Type MV·lJO MV-lOS Type MV-lJO MV-lOS<br />
Table 310.69 Ampaclties of Insulated Single Copper<br />
Conductor Isolated in Air Based on Conductor Temperatures<br />
of 90°C (194°F) <strong>and</strong> 105°C (221°F) <strong>and</strong> Ambient Air<br />
Temperature of 40°C (104°F)<br />
Temperature Rating of Conductor [See Table ....]<br />
2ool-S000 Volts SOOl-lS,OOO lS,ool-3S,OOO<br />
Ampacity Volts Ampacity Volts Ampacity<br />
Conductor lJOoC lOSoC lJOoC<br />
8 65 74<br />
lOSoC 90°C lOSoC<br />
6 90 99 100 110<br />
Size (194°F) (221°F) (194°F) (221°F) (194°F) (221°F)<br />
4 120 130 130 140 (AWG Type Type Type Type Type Type<br />
2 160 175 170 195 or kcmil) MV-90 MV-lOS MV-lJO MV·lOS MV-lJO MV-lOS<br />
I 185 205 195 225<br />
8 83 93<br />
1/0 215 240 225 255 6 110 120 110 125<br />
2/0 250 275 260 295 4 145 160 150 165<br />
3/0 290 320 300 340 2 190 215 195 215<br />
4/0 335 375 345 390 1 225 250 225 250 225 250<br />
250 375 415 380 430 1/0 260 290 260 290 260 290 ..,J<br />
350 465 515 470 525 2/0 300 330 300 335 300 330<br />
500 580 645 580 650 3/0 345 385 345 385 345 380<br />
750 750 835 730 820 4/0 400 445 400 445 395 445<br />
1000 880 980 850 950<br />
250 445 495 445 495 440 490<br />
350 550 615 550 610 545 605<br />
500 695 775 685 765 680 755<br />
750 900 1000 885 990 870 970<br />
1000 1075 1200 1060 1185 1040 1160<br />
1250 1230 1370 1210 1350 1185 1320<br />
1500 1365 1525 1345 1500 1315 1465<br />
1750 1495 1665 1470 1640 1430 1595<br />
2000 1605 1790 1575 1755 1535 1710<br />
70-156<br />
NATIONAL ELECTRICAL CODE<br />
2008 Edition
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