Someone advertised 22 metres of 3 core 16 sq. mm SWA on Ebay over the
weekend and it went for £21, which is less than the value of the Copper
I suspect. Seller said it weighed 25 kg but that doesn't seem right.

Assuming Copper weighs 8200 kg per cubic meter,

3-core 16sq mm is 48 sq. mm * 22,000 centimetres
so, 0.48 * 22,000 = 10,560 cubic cms
1 cubic cm = 8.2 grams ,
total mass of copper is 10,560 * 8.2 = 86592 gms = 86.593 kg

This seems too high, where have I gone wrong ?, else the value of the
copper was a lot more than £21


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AD

22 metres = 2,200 centimetres not 22,000 centimetres.
I assume your density and maths are OK.
That makes the copper weigh 8.6kg

Andrew wrote:
Someone advertised 22 metres of 3 core 16 sq. mm SWA on Ebay over the
weekend and it went for £21, which is less than the value of the Copper
I suspect. Seller said it weighed 25 kg but that doesn't seem right.

Assuming Copper weighs 8200 kg per cubic meter,

3-core 16sq mm is 48 sq. mm * 22,000 centimetres
^^^^^^

There's your problem.

Try 2,200 cm.


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Grunff