Lessons In Electric Circuits -- Volume V

Chapter 3 CONDUCTOR AND INSULATOR TABLES

Copper wire gage table

Soild copper wire table:

Size        Diameter         Cross-sectional area       Weight
AWG          inches        cir. mils     sq. inches   lb/1000 ft
================================================================
4/0 -------- 0.4600 ------- 211,600 ------ 0.1662 ------ 640.5
3/0 -------- 0.4096 ------- 167,800 ------ 0.1318 ------ 507.9
2/0 -------- 0.3648 ------- 133,100 ------ 0.1045 ------ 402.8 
1/0 -------- 0.3249 ------- 105,500 ----- 0.08289 ------ 319.5 
1 ---------- 0.2893 ------- 83,690 ------ 0.06573 ------ 253.5 
2 ---------- 0.2576 ------- 66,370 ------ 0.05213 ------ 200.9 
3 ---------- 0.2294 ------- 52,630 ------ 0.04134 ------ 159.3 
4 ---------- 0.2043 ------- 41,740 ------ 0.03278 ------ 126.4 
5 ---------- 0.1819 ------- 33,100 ------ 0.02600 ------ 100.2 
6 ---------- 0.1620 ------- 26,250 ------ 0.02062 ------ 79.46 
7 ---------- 0.1443 ------- 20,820 ------ 0.01635 ------ 63.02 
8 ---------- 0.1285 ------- 16,510 ------ 0.01297 ------ 49.97 
9 ---------- 0.1144 ------- 13,090 ------ 0.01028 ------ 39.63 
10 --------- 0.1019 ------- 10,380 ------ 0.008155 ----- 31.43 
11 --------- 0.09074 ------- 8,234 ------ 0.006467 ----- 24.92 
12 --------- 0.08081 ------- 6,530 ------ 0.005129 ----- 19.77 
13 --------- 0.07196 ------- 5,178 ------ 0.004067 ----- 15.68 
14 --------- 0.06408 ------- 4,107 ------ 0.003225 ----- 12.43 
15 --------- 0.05707 ------- 3,257 ------ 0.002558 ----- 9.858 
16 --------- 0.05082 ------- 2,583 ------ 0.002028 ----- 7.818 
17 --------- 0.04526 ------- 2,048 ------ 0.001609 ----- 6.200
18 --------- 0.04030 ------- 1,624 ------ 0.001276 ----- 4.917 
19 --------- 0.03589 ------- 1,288 ------ 0.001012 ----- 3.899 
20 --------- 0.03196 ------- 1,022 ----- 0.0008023 ----- 3.092 
21 --------- 0.02846 ------- 810.1 ----- 0.0006363 ----- 2.452 
22 --------- 0.02535 ------- 642.5 ----- 0.0005046 ----- 1.945 
23 --------- 0.02257 ------- 509.5 ----- 0.0004001 ----- 1.542 
24 --------- 0.02010 ------- 404.0 ----- 0.0003173 ----- 1.233 
25 --------- 0.01790 ------- 320.4 ----- 0.0002517 ----- 0.9699
26 --------- 0.01594 ------- 254.1 ----- 0.0001996 ----- 0.7692
27 --------- 0.01420 ------- 201.5 ----- 0.0001583 ----- 0.6100 
28 --------- 0.01264 ------- 159.8 ----- 0.0001255 ----- 0.4837 
29 --------- 0.01126 ------- 126.7 ----- 0.00009954 ---- 0.3836 
30 --------- 0.01003 ------- 100.5 ----- 0.00007894 ---- 0.3042 
31 -------- 0.008928 ------- 79.70 ----- 0.00006260 ---- 0.2413 
32 -------- 0.007950 ------- 63.21 ----- 0.00004964 ---- 0.1913 
33 -------- 0.007080 ------- 50.13 ----- 0.00003937 ---- 0.1517 
34 -------- 0.006305 ------- 39.75 ----- 0.00003122 ---- 0.1203 
35 -------- 0.005615 ------- 31.52 ----- 0.00002476 --- 0.09542 
36 -------- 0.005000 ------- 25.00 ----- 0.00001963 --- 0.07567 
37 -------- 0.004453 ------- 19.83 ----- 0.00001557 --- 0.06001 
38 -------- 0.003965 ------- 15.72 ----- 0.00001235 --- 0.04759 
39 -------- 0.003531 ------- 12.47 ---- 0.000009793 --- 0.03774 
40 -------- 0.003145 ------- 9.888 ---- 0.000007766 --- 0.02993 
41 -------- 0.002800 ------- 7.842 ---- 0.000006159 --- 0.02374 
42 -------- 0.002494 ------- 6.219 ---- 0.000004884 --- 0.01882 
43 -------- 0.002221 ------- 4.932 ---- 0.000003873 --- 0.01493 
44 -------- 0.001978 ------- 3.911 ---- 0.000003072 --- 0.01184

Copper wire ampacity table

Ampacities of copper wire, in free air at 30^o C:

======================================================== 
|                      INSULATION TYPE:                |
|         RUW, T           THW, THWN        FEP, FEPB  | 
|           TW               RUH            THHN, XHHW | 
======================================================== 
Size    Current Rating   Current Rating   Current Rating 
AWG     @ 60 degrees C   @ 75 degrees C   @ 90 degrees C 
======================================================== 
20 -------- *9 ----------------------------- *12.5 
18 -------- *13 ------------------------------ 18  
16 -------- *18 ------------------------------ 24  
14 --------- 25 ------------- 30 ------------- 35  
12 --------- 30 ------------- 35 ------------- 40  
10 --------- 40 ------------- 50 ------------- 55  
8 ---------- 60 ------------- 70 ------------- 80  
6 ---------- 80 ------------- 95 ------------ 105  
4 --------- 105 ------------ 125 ------------ 140  
2 --------- 140 ------------ 170 ------------ 190  
1 --------- 165 ------------ 195 ------------ 220  
1/0 ------- 195 ------------ 230 ------------ 260   
2/0 ------- 225 ------------ 265 ------------ 300  
3/0 ------- 260 ------------ 310 ------------ 350  
4/0 ------- 300 ------------ 360 ------------ 405

* = estimated values; normally, wire gages this small are not manufactured with these insulation types.

Coefficients of specific resistance

Specific resistance at 20^o C:

Material      Element/Alloy        (ohm-cmil/ft)          (ohm-cm) 
====================================================================
Nichrome ------- Alloy ---------------- 675 ------------- 112.2^-6
Nichrome V ----- Alloy ---------------- 650 ------------- 108.1^-6
Manganin ------- Alloy ---------------- 290 ------------- 48.21^-6
Constantan ----- Alloy ---------------- 272.97 ---------- 45.38^-6
Steel* --------- Alloy ---------------- 100 ------------- 16.62^-6
Platinum ------ Element --------------- 63.16 ----------- 10.5^-6
Iron ---------- Element --------------- 57.81 ----------- 9.61^-6
Nickel -------- Element --------------- 41.69 ----------- 6.93^-6
Zinc ---------- Element --------------- 35.49 ----------- 5.90^-6
Molybdenum ---- Element --------------- 32.12 ----------- 5.34^-6
Tungsten ------ Element --------------- 31.76 ----------- 5.28^-6
Aluminum ------ Element --------------- 15.94 ----------- 2.650^-6
Gold ---------- Element --------------- 13.32 ----------- 2.214^-6
Copper -------- Element --------------- 10.09 ----------- 1.678^-6
Silver -------- Element --------------- 9.546 ----------- 1.587^-6

* = Steel alloy at 99.5 percent iron, 0.5 percent carbon.

Temperature coefficients of resistance

Temperature coefficient (α) per degree C:

Material     Element/Alloy         Temp. coefficient 
===================================================== 
Nickel -------- Element --------------- 0.005866    
Iron ---------- Element --------------- 0.005671    
Molybdenum ---- Element --------------- 0.004579    
Tungsten ------ Element --------------- 0.004403    
Aluminum ------ Element --------------- 0.004308    
Copper -------- Element --------------- 0.004041    
Silver -------- Element --------------- 0.003819    
Platinum ------ Element --------------- 0.003729    
Gold ---------- Element --------------- 0.003715    
Zinc ---------- Element --------------- 0.003847    
Steel* --------- Alloy ---------------- 0.003  
Nichrome ------- Alloy ---------------- 0.00017
Nichrome V ----- Alloy ---------------- 0.00013
Manganin ------- Alloy ------------ +/- 0.000015    
Constantan ----- Alloy --------------- -0.000074

* = Steel alloy at 99.5 percent iron, 0.5 percent carbon

Critical temperatures for superconductors

Critical temperatures given in Kelvins

Material     Element/Alloy      Critical temperature(K)
======================================================       
Aluminum -------- Element --------------- 1.20
Cadmium --------- Element --------------- 0.56
Lead ------------ Element --------------- 7.2
Mercury --------- Element --------------- 4.16
Niobium --------- Element --------------- 8.70
Thorium --------- Element --------------- 1.37
Tin ------------- Element --------------- 3.72 
Titanium -------- Element --------------- 0.39
Uranium --------- ELement --------------- 1.0
Zinc ------------ Element --------------- 0.91
Niobium/Tin ------ Alloy ---------------- 18.1
Cupric sulphide - Compound -------------- 1.6

Note: all critical temperatures given at zero magnetic field strength.

Dielectric strengths for insulators

Dielectric strength in kilovolts per inch (kV/in):

Material*         Dielectric strength 
=========================================    
Vacuum --------------------- 20            
Air ------------------------ 20 to 75      
Porcelain ------------------ 40 to 200     
Paraffin Wax --------------- 200 to 300    
Transformer Oil ------------ 400           
Bakelite ------------------- 300 to 550    
Rubber --------------------- 450 to 700    
Shellac -------------------- 900           
Paper ---------------------- 1250          
Teflon --------------------- 1500          
Glass ---------------------- 2000 to 3000  
Mica ----------------------- 5000

* = Materials listed are specially prepared for electrical use

Tables of specific resistance and temperature coefficient of resistance for elemental materials (not alloys) were derived from figures found in the 78th edition of the CRC Handbook of Chemistry and Physics. Superconductivity data from Collier's Encyclopedia (volume 21, 1968, page 640).