:: the problem with MADE in CHINA cables is ...

i bet many hobbyist have come across the question of, HOW GENUINE are these copper cables made in CHINA?

you don't know until you buy some and then measure the overall resistances and calculate vs the cross section area.

below are some data from websites



item 平方 (mm2) CNY $$$/mm2 Ω/1000m stranding AWG Wt(Kg) / 1000m nΩ.m Mils^2 Ondk 1s
(amps)
Ondk 999s
(amps)
30C rise to 60C
(amps)
*LQ = low quality
hobby RC shop 532620918891 25.14 $50.00 1.989 1.25 5000/.08 4
31.43 38967 3915.8 123.9 145.3 LQ
hobby RC shop 45367363912 0.75 $1.50 2.000 39.50 150/.08 18
29.63 1163 124.0 3.9 13.7 LQ
hobby RC shop 532620918891 12.07 $18.00 1.491 2.60 2400/.08 7
31.38 18709 1883.1 59.6 87.7 LQ
hobby RC shop 532620918891 16.09 $25.00 1.554 1.90 3200/.08 6
30.57 24940 2576.7 81.5 109.8 LQ
Braiding 43964956175 8.45 $4.80 0.568 2.28 480/.075
85 19.30 13098 2143.5 67.8 111.5
Braiding 39055875646 4.24 $2.40 0.566 4.55 240/.075
43 19.30 6572 1075.5 34.0 69.3
Braiding 22552776369 25.45 $15.00 0.589 0.76 1440/.075
254 19.30 39448 6455.6 204.2 238.7

calmont 24.90

0.73 19/(16) 3 227 18.18 38595 6705.1 212.1 249.6 sample

calmont 2.38

9.01 1176/(44) 14 23.8 21.44 3689 543.4 17.2 41.9 sample

calmont 14.70

1.39 1813/(38) 6 147 20.43 22785 3522.5 111.4 154.4 sample

calmont 5.37

3.61 133/.09 10 125 19.39 8324 1355.9 42.9 81.2 sample

calmont 0.33

61.40 66/40 22 3.1 20.26 512 79.8 2.5 11.3 sample

calmont 8.37

2.10 1 8 74.4 17.58 12974 2330.9 73.7 121.6 sample

calmont 13.30

1.32 1 6 118 17.56 20615 3707.9 117.3 167.6 sample
welding lead 16756217099 16.00 $9.00 0.563 1.24
5
19.84 24800 3948.0 124.9 168.5
welding lead 16756217099 10.00 $7.00 0.700 1.98
7
19.80 15500 2472.5 78.2 122.1
welding lead 16756217099 25.00 $13.00 0.520 0.79
3
19.75 38750 6196.9 196.1 230.4

LIBAN 6.00

3.08 1
53 18.48 9300 1589.5 50.3 92.0 sample
Earthing Cu 44392603636 25.00 $16.50 0.660 0.91
3
22.75 38750 5379.7 170.2 200.0
AGR silicone 545870228257 6.00 $3.10 0.517 3.39 84/0.3 10
20.34 9300 1444.1 45.7 83.6
AGR silicone 545870228257 4.00 $2.22 0.555 5.09 56/0.3

20.36 6200 961.8 30.4 63.1
PTFE 528684442893 1.00 $0.88 0.880 19.00 19/0.26

19.00 1550 257.7 8.2 26.0
RV PVC 534957029863 1.00 $0.63 0.630
1


1550



AGR silicone 22501955879 0.75 $0.50 0.667 26.70 42/.15

20.03 1163 183.4 5.8 20.2
PTFE 546896145948 0.35 $0.70 2.000 49.50 19/.16 22
17.33 543 99.0 3.1 13.8

Wiki AWG 8 8.37

2.06
8
17.24 12974 2376.9 75.2 124.0 sample

Wiki AWG 6 13.30

1.30
6
17.29 20615 3765.8 119.1 170.2 sample

Wiki AWG 4 21.20

0.82
4
17.38 32860 5971.5 188.9 233.6 sample

Wiki AWG 1 42.40

0.41
1
17.38 65720 11943.0 377.9 376.9 sample

annealed






17.2



COPPER

not annealed






16.8



COPPER
AMASS 36457901332 16.09 $29.00 1.802 1.21 3200/.08 6
19.47 24940 4045.7 128.0 172.4 original?
AMASS 36457901332 8.29 $14.00 1.689 4.10 1650/.08 8
33.99 12850 1194.0 37.8 62.5 LQ
WIPOUS 534955000055 8.51 $7.14 0.839 2.16 168/.254 8
18.38 13191 2266.7 71.7 117.7
WIPOUS 534955000055 21.08 $12.00 0.569 0.88 196/.37 4
18.55 32674 5563.2 176.0 218.0
WIPOUS 534955000055 5.32 $4.13 0.776 3.41 101/.254 10
18.14 8246 1435.7 45.4 86.2

you can try to measure the circumference of the conductor by wrapping it with many turns of a thin wire like AWG40-44, then unwrap it and find out the diameter, then find out the approximate area.

the fixed constants we know in life are the resistivity of COPPER (about 17.2nΩ.m annealed). by measuring the resistance of a known length (with the known cross section area), we can find the resistivity. you will of course need a super sensitive low resistance ohm meter (assuming this will not be a problem)

column description
1 = cable general category
2 = cable ID if any
3 = conductor area
4 = CNY price if any
5 = cable general category
6 = unit price per area
7 = stated resistance per km
8 = conductor stranding
9 = equiv AWG no.
10 = stated wt per km
11 = stated/calculated resistivity
12 = equiv area in mils
13 = ONDERDONK current capacity
14 = ONDERDONK current capacity
15 = Temp rise approx current capacity (approx PREECE)
16 = remarks

but without doing so, we can see already from the data provided by vendors, there are already things not quite right with the quality of the conductors. the many sample/types shown (number tags are TAOBAO item IDs) allows us to see that if a finely stranded cable have a worse case resistivity of about 21nΩ.m, why are those MADE in CHINA conductors going off into 30nΩ.m?

this would mean when high current circuits are deployed, you need to buy about 33% more cables (and more weight) to secure a certain current carrying capacity.

by relying  on the fact that 99.99% of buyers do not own a low-ohms meter to cross check the quality of the cables, sellers can promote "miraculous geniune copper cables" when in fact they could be copper cladded steel.

have you measured some lately?

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