BREAK DOWN VOLTAGE FOR ENAMELLED ROUND COPPER WINDING WIRES 
(BASIS : IS 13730 - .. & IS 13778 - 5)
Nominal Conductor Test Specimen Test Specimen Preparation Breakdown Voltage 
Diameter Configuration Force Twists per Volts (min)
(SWG) (MM)   (N) 125 mm Grade 1  Grade 2 Grade 3
11 2.946 Aluminium foil
wrapped wire
- - 1300 2500 3800
12 2.642 - - 1300 2500 3800
13 2.337 Twisted Pair 108 3 2700 5000 7600
14 2.032 54 4 2700 5000 7600
15 1.829 2700 5000 7600
16 1.626 2700 5000 7600
17 1.422 27 6 2700 5000 7600
18 1.219 2700 5000 7600
19 1.016 13.50 8 2700 5000 7600
20 0.914 2700 5000 7600
21 0.813 2700 5000 7600
22 0.711 7.00 12 2600 4900 7400
23 0.610 2600 4800 7100
24 0.559 2500 4600 7100
25 0.508 2500 4600 7100
26 0.457 3.40 16 2400 4600 7000
27 0.417 2300 4400 6800
28 0.376 2300 4400 6600
29 0.345 1.70 23 2300 4300 6400
30 0.315 2200 4100 6100
31 0.295 2200 4100 6100
32 0.274 2200 4000 5800
33 0.254 2200 4000 5800
34 0.234 0.85 33 2100 3900 5500
35 0.213 1900 3700 5200
36 0.193 1800 3500 5100
37 0.173 1700 3300 4700
38 0.152 1700 3200 4400
39 0.138 1600 3000 4200
40 0.122 1500 2800 4100
41 0.112 1300 2700 3900
42 0.102 1300 2700 3900
43 0.091 Cylinder
Wrap
0.40 - 500 950 1400
44 0.081 0.30 - 500 900 1300
45 0.071 0.20 - 425 700 1100
46 0.061 0.15 - 375 700 -
47 0.051 0.15 - 325 650 -
48 0.041 0.10 - 275 550 -
Notes : 1) For intermediate nominal conductor diameter breakdown voltage value for the next largest nominal conductor diameter  shall be taken
2) 1 N = 0.102 kg
Note: In view of continuous improvements in design & process specifications given above are subject to change without notice.