How to read a marking
Letters in the marking
| Letter | Meaning |
|---|---|
| A (А) | aluminium core (no leading letter - the core is copper) |
| V (В) | PVC (vinyl) insulation or sheath; the first V is core insulation, the second the outer sheath |
| P (П) | polyethylene insulation; at the start of a wire type - "provod" (wire) |
| G (Г) | at the end of a cable type - no protective cover ("goly", bare); in a wire type - flexible core |
| Sh (Ш) | cord (ShVVP) or hose-type sheath (Shv - vinyl hose) |
| B (Б) | steel tape armour (VBbShv - for direct burial) |
| K (К) | at the start of a type - cable (KG - flexible cable) |
| U (У) | installation wire (PuV, PuGV - wires for fixed wiring) |
| ng (нг) | does not spread flame when installed in bundles; the bracketed letter is the test category: ng(A) is stricter than ng(B) |
| LS | low smoke - reduced smoke and gas emission when burning |
| FR | fire resistant - keeps the circuit alive in fire (for safety systems) |
Common types
| Type | Decoded | Typical use |
|---|---|---|
| VVG (ВВГ) | copper, PVC insulation and sheath, no protective cover | fixed wiring in dry rooms |
| VVGng(A) | VVG that does not spread flame | bundled runs: chases, trays, risers |
| VVGng(A)-LS | VVGng with low smoke emission | apartments and houses - the default choice for new wiring |
| AVVG (АВВГ) | the same but with aluminium cores | budget lines; not used for new residential wiring below 16 mm² - copper only |
| NYM | European analogue of VVGng: copper, PVC, chalk-filled rubber inner sheath | indoor wiring; easy to strip but degrades in sunlight |
| PVS (ПВС) | flexible connecting wire, vinyl insulation, copper cores | extension cords, connecting appliances, portable leads |
| ShVVP (ШВВП) | flat flexible vinyl cord | light appliances: lamps, chargers, small kitchen devices |
| PuV / PV-1 (ПуВ) | installation wire, solid rigid core | wiring inside switchboards, fixed jumpers |
| PuGV / PV-3 (ПуГВ) | flexible installation wire, stranded core | switchboards (with ferrules), earthing jumpers, moving sections |
| KG (КГ) | flexible cable, rubber insulation and sheath | construction sites, welders, outdoor extension leads, cold weather |
| VBbShv (ВБбШв) | copper, PVC, steel tape armour, hose sheath | direct burial, underground service entry |
| SIP (СИП) | self-supporting insulated wire, aluminium | overhead lines and the overhead drop from a pole to the house |
| PUNP (ПУНП) | flat universal wire (obsolete spec) | avoid: undersized cross-section and insulation; banned for new wiring |
How to tell a quality cable
- Real cross-section = the stated one. The most common cheat is an undersized conductor (marked 2.5 mm², actually 2.0-2.2 mm²). Check it two ways: measure the conductor diameter with calipers and compare with the table below, or measure the conductor resistance - it must not exceed the standard.
- Real copper, not CCA. The cheap fake is copper-clad aluminium (CCA): copper on the outside, aluminium inside. Good copper is pink-red, soft and pliable, and does not spring back. CCA gives itself away by silvery metal at a cut or scratch, by stiffness and low weight. Test: bend the conductor back and forth a few times - copper bends, CCA snaps.
- A standard, not a loophole spec. A quality cable has a real standard printed on the sheath (e.g. IEC 60227/60245, or GOST 31996 for VVG power cables), plus the type, cores×cross-section, factory and length markers. A vague in-house spec (Russian «ТУ») is a warning sign; obsolete PUNP/PBPP must not be used for fixed wiring.
- Insulation. Even thickness, no lumps, bubbles or bare spots; the material is not sticky and does not crack when bent in the cold, and sits tightly on the conductor. The printed marking is crisp and does not rub off with a finger.
- Coil weight. Copper is heavy: an undersized conductor or CCA makes the coil noticeably lighter than it should be. If the seller allows, weigh it and compare with the rated mass.
- Length in the coil. A frequent cheat is short measure: the coil says 100 m but really holds 90. The length is printed along the sheath, so the remainder can be checked.
Conductor resistance: the standard limit
| Cross-section, mm² | Ø copper conductor, mm | Max resistance, Ω/km |
|---|---|---|
| 1.5 | 1.38 | 12.1 |
| 2.5 | 1.78 | 7.41 |
| 4 | 2.26 | 4.61 |
| 6 | 2.76 | 3.08 |
| 10 | — | 1.83 |
| 16 | — | 1.15 |
How to read the table
The figures are the maximum DC resistance of a copper conductor at 20 °C per IEC 60228 (GOST 22483): a genuine cable measures no higher. The diameter is for a solid (single-wire) conductor - easy to measure with calipers, cross-section S = π·d²/4. The 10 and 16 mm² sizes are usually stranded, so you check their resistance rather than a diameter.
How to measure resistance
Take a piece of known length, measure the conductor resistance and scale it to 1 km (for 10 m, multiply the result by 100). The resistance is hundredths of an ohm, so an ordinary multimeter is imprecise here: it is more accurate to measure a full 100 m coil and to short the probes first and subtract their own resistance. A value well above the table means the cross-section is undersized. Another way is the voltage-drop method: pass a known current through the conductor and find the resistance with Ohm's law.
Cross-section is chosen by current
The type defines the installation conditions, while the load is carried by the cross-section. Pick the cross-section by power and current with the wire size calculator, and check long runs with the voltage drop calculator.
A reference is not a design
The cable requirements for a specific project (fire class, installation method, fire-resistant lines for safety systems) are set by codes and the project documentation.