It appears, according to GOST 22483, the actual cable cross section may be below the nominal (). Of course, all manufacturers follow GOST underestimate section.
GOST 22483-77 "Conductors made of copper and aluminum cable, wires and cords. Main parameters. Technical requirements "is not standardized section, and normalize the only resistance. There's even a point 1.4a.: "The actual cross section may differ from the nominal electrical resistance when compliance with this standard."
In Table 1, "CLASS 1 Cores solid and stranded cables and wires" are the following resistance values kilometer copper conductor:
1.5 mm² - 12.1 ohms
2.5 mm² - 7.41 Ohm
4 mm² - 4.61 Ohm
6 mm² - 3.08 Ohm
Via calculator wire resistance easy to calculate what the actual section are consistent with such resistance:
1.5 - 12.1 ohm - 1.389 mm² (1.3295 mm diameter) - underestimation of 7.4%;
2.5 - 7.41 Ohm - 2.2673 mm² (diameter 1.699 mm) - 9.3% underestimation;
4 - 4.61 Ohm - 3.644 mm² (diameter 2.154 mm) - 8.9% underestimation;
6 - 3.08 Ohm - 5.455 mm² (2.6352 mm diameter) - 9.1% underestimation.
In fact, GOST allows manufacturers underestimate the cable cross section at 7-9%, so that the conductor diameter Gostovskaya cable must be at least:
1.5 - 1.3 mm;
2.5 - 1.7 mm;
4 - 2.2 mm;
6 - 2.6 mm.
With the help of a barbell-digital compass I measured several strands of cables VVG. To control measure diameter of the drill shank 2 mm.
Cable VVG 3x1.5 GOST bought 10 years ago, which I have used for wiring in the apartment.
Resistance to one meter cable - 13 milliohms.
Conductor diameter 1.32 mm, the cross section of 1.37 mm². Corresponds to GOST.
VVG APG cable (A) LS 3x2.5 GOST. Manufacturer - ESC ElektroSilovoyKabel, Nizhny Novgorod. I bought a week ago.
It's funny that GOST 31565-2012 indicated on the label, it's just the fire safety requirements to cable products, not standard on the cable itself.
Resistance to one meter cable - 8 milliohms.
Diameter 1.69 mm, section 2.24 mm². Corresponds to GOST.
Cable VVG 3x6 GOST store Castorama.
Diameter 2.64 mm, section 5.47 mm². Corresponds to GOST.
But sales have cables made not only guests, but also according to TU. Their cross-section is often underestimated by half (!). Recently I talked about the wire PUGNPbm 2x1.5, which is a real cross-section It turned 0.77 mm² (ammo1.livejournal.com/1043045.html).
But at the same store Castorama cable VVGbm-Png (A), 3x4 mm² TU.
Diameter 1.93 mm, section 2.92 mm². Underestimated by almost a third.
Almost all domestic power cables are sold in Russia, have underestimated section. In cables, produced according to GOST, reduction of up to 10% (GOST and so permits), the cables have issued TU, reduction may be up to 50%.
Probably an understatement to GOST should simply "to understand and forgive," but rather to keep in mind that the actual cross-section cable, on which is written 2.5 mm² to 2.3 mm² about, and in fact, on which is written 1.5 mm² - about 1.3 mm². In the near future I'll check what the actual load currents can withstand these cables.
© 2019 Alex Nadozhin