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diy solar

Have we got fake solar wire around the market?

B

Boron

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Oct 26, 2023
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UK SE Kent
I have taken delivery of samples of TUV solar cables 6mm2. I was curious to know if these conformed to the specs. Correct me if I am wrong but we should have tinned Cu wire 0.3mm dia x 84 strands. This gives 5.94mm2 thats ok for 70A. The samples I got
a) looked genuine printed on the outside "6 sqmm DUCAB C BICC PV cable 1.5kV but it had 84 x 0.25 dia core = 4.124mm2
b) un marked plain black with inner white sheath 83 x 0.22mm dia core = 3.193mm2

Clearly a very important discrepancy

Before I go Nuclear with the suppliers, has anyone else noticed this issue as I took one look at the cable construction and immediately thought that its an obvious area for cheating.

BTW Ive already been reprimanded for over thinking a topic on this board. Is my concern here justified?
 
I bought 1/0 wire from inverters-r-us via Amazon. Com and it was the smallest 1/0 wire, with the least amount of copper, that I have ever bought.
 
Well guys, I have opened up a can of worms here and rattled a few cages with dodgy dealers on EB. I suspect (correct me if Im wrong Cousins and Canadians), but you have some serious regulatory muscle to back you up if anyone is trying to sell you undersized solar cable and the EE has to sign off on your installation with his UL stamp etc) so thats very likely you dont have an issue that I am finding in UK/EU. Same goes down under as the Cobbers are way ahead of us in DIY Solar energy.
I have some cable with a printed jacket TUV etc 6mm2 but when I measure it, its nearer 4mm2 and that has got me alarmed. I have more samples coming from various sources - takes time and I am set up to measure accurately. Its not easy and originally it was done from a cable drum with 1km or 1000ft. https://nvlpubs.nist.gov/nistpubs/Legacy/hb/nbshandbook100.pdf and https://archive.org/details/copperwiretables31unituoft/page/n9/mode/1up?view=theater all ancient original standards. and International Annealed Copper Standard (IACS)https://en.wikipedia.org/wiki/International_Annealed_Copper_Standard.
The criteria is set as resistance ohms per 1km for a given mm2 (3.5 / 5.3 ohms for 6mm2/4mm2 and so on.)
So how the manufacturer achieves this is trade secret ie how many strands of what dia to meet the spec.
FYI the strands of common power cable are counter wound in concentric circles.
As you are dying to ask - the maximum number of strands for stiff cable is 7 (2 layers 1+6 strands), with flexible cable its generally 6 layers Max 61 strands but std is 56 4mm2 and Max 91 but std 84 6mm2.

So plenty of room for fudging about.

To make matters worse there is a modern technique of using ETP wire aka Oxygen free and annealed to get better conductivity - and use less material - more room for chicanery.

But we naive DIY buyers use cable according to csa or AWG 10/12.

Unless you are a professional installer you wont have a 1km drum on hand. Making low ohmic measurements needs high res DVM and a current source of 10Adc. Contact resistance can be surprisingly high without special skill.

I am working with a major Cable manufacturer (EU) who was shocked when I told him of cable being sold with the Company name in the listing (fraudulently)

Hope you guys are ok - have you checked? - who checks cable?
 
Boron said:
...

Hope you guys are ok - have you checked? - who checks cable?
Click to expand...
Yeah there is a lot of wire being sold that does not meet regular standards. Copper has become expensive enough that big dollars can be be made by shorting the amount used. Some is CCA (copper clad aluminum) and some the insulation is of poor quality. Even the name brands ( UL listed ) have to be careful if they source their stuff from China because of the games being played to maximize profits.

Also the conversion from metric, Chinese metric and standard allows a bit of slop to exist. Interesting your find that games with wire resistance is also at play.
 
Many of the amazon ads specifically state the count and wire size. Whether or not that's what they are actually shipping, can't say until I get home and measure my wire.
78 strands of .295mm
105 X .254mm
84 X .285mm
 
Tulex said:
Many of the amazon ads specifically state the count and wire size. Whether or not that's what they are actually shipping, can't say until I get home and measure my wire.
78 strands of .295mm
105 X .254mm
84 X .285mm
Click to expand...
@Tulex Good news 4u
78 x .295 =5.33mm2 = 10AWG
105x .254 = 5.32mm2 = 10AWG
84x .285 = 5.36mm2 = 10AWG
10AWG = 5.26mm2

good spec.(y)
 
Is tin plated wire a requirement for PV wire? I try to use tin plated wire whenever possible in mobile power systems.

For solar PV wire, I am not that impressed with the MC4 connectors and the results of crimping in the field, so I just buy it pre-made with MC4s on each end and cut it in half.
 
Boron said:
Unless you are a professional installer you wont have a 1km drum on hand. Making low ohmic measurements needs high res DVM and a current source of 10Adc. Contact resistance can be surprisingly high without special skill.
Click to expand...
No need for 10A power supply and even cheapo multimeter is enough.

1 meter piece of 4mm2 vs 6mm2 wire is about 4mOhm vs. 2.6mOhm resistance. 0.1mOhm would be plenty good for resolution.

Assume you have 1A capable power supply (even a battery and suitable light bulb would do it in a pinch) you need to be able to measure down to 0.1mV to get 0.1mOhm resolution. Even the infamous 5 dollar DT-830B multimeter is enough for this.

For more precision Aneng AN870, AN8009, Aneng Q1 ,Aneng SZ20 are some good budget options (20-40 usd) with 0.001mV resolution.

10A power supply and 1uV resolution volt meter let you measure things down to 0.0001mOhm resolution, more than enough to measure even short pieces of 4/0 or 95mm2 cables. 1A power supply and AN8009 would work fine for 4/0 cable if it is more than half meter long.
 
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