VVG or VVGng: which cable should I choose and what is the difference?

Introduction: two versions of the same cable

VVG and VVGng are two designations found in every power supply project for residential or public buildings. At first glance, the difference is only in the two letters “ng”, but it is precisely these letters that determine whether the facility will pass the fire inspection. Both cables are power cables with copper conductors, PVC insulation and sheath, manufactured according to GOST 31996‑2012. However, VVG is the basic version, while VVGng is the same design, but with a sheath made of reduced‑flammability PVC compound.

The key difference becomes apparent during group laying: VVGng does not propagate combustion if a neighbouring cable catches fire. Ordinary VVG does not offer such a guarantee. Hence the division of applications: VVG is used where fire safety requirements are low, while VVGng is used in residential and public buildings, on escape routes and in cable structures. More details on the design and classification of power lines are given in the overview about power cables.

Comparative table of VVG and VVGng

Fire safety: why the “ng” index appeared

Standard PVC compound supports combustion, and when several cables are laid in the same tray, a fire in one spreads to the neighbouring ones, turning the cable route into a fire‑conducting cord. It was precisely to prevent this scenario that reduced‑flammability compound was developed. A cable with the ng(A) index passes tests according to GOST IEC 60332‑3‑22: a bundle of cables is ignited with a gas burner, and the flame must not spread beyond a certain mark. The letter “A” in parentheses indicates the strictest test category in terms of the volume of combustible material.

VVG without “ng” is permitted to be laid singly or in places where the fire load is not strictly regulated: for example, in a cable basement with automatic fire extinguishing, or on an open overpass outside the building. But inside a residential building, in a chase, behind drywall, in a corrugated tube — the requirements of SP 256.1325800.2016 prescribe the use of only cables with the ng index. Saving on this index results in a directive from the State Fire Supervision and refusal to accept the facility.

Versions LS, LSLTx and A-LS: what the letters mean

The basic VVGng version only addresses the issue of flame propagation. But during a fire, PVC releases dense black smoke and hydrogen chloride, which, when combined with water, forms hydrochloric acid. To reduce this hazard, smoke inhibitors are added to the formulation, and the cable receives the LS index — Low Smoke. The additional letter “A” before LS indicates the flame‑spread category, while LSLTx indicates reduced toxicity of combustion products. For escape routes, kindergartens, hospitals, shopping centres, LS is mandatory. The difference between VVGng and VVGng‑LS is covered in more detail in the article VVGNG.

Flat versions of VVGng and VVGng‑LS are marked with an additional letter “P” — VVG‑Png(A)-LS. They are convenient for laying under plaster, as they are thinner and their wide sides are easily fixed in chases. Flat cables are not intended for outdoor use. All versions — both flat and round — are available with solid or stranded copper conductors; flexible VVGng is made with class 5 conductors. The catalogue of copper power cables is presented in the section VVG cable.

Electrical characteristics, cross‑section and load

In terms of electrical parameters, VVG and VVGng are completely identical. The continuous permissible current depends on the cross‑section, number of cores and installation method, and is determined by the PUE. For a three‑core copper cable in air: 1.5 mm² — 19 A, 2.5 mm² — 27 A, 4 mm² — 35 A, 6 mm² — 45 A, 10 mm² — 63 A. When laid in corrugated tube or pipe, currents are reduced by 10‑15%. From here it is easy to recalculate power: a single‑phase load at 220 V for a 2.5 mm² cross‑section will be about 5.9 kW, and for a three‑phase 380 V — about 15 kW with a symmetrical load on 2.5 mm². When choosing a cross‑section, start from the calculated power of consumers, with a margin of 20‑30%.

The outer diameter and weight per metre depend on the number of cores and cross‑section. For example, VVGng 3×2.5 has a diameter of about 10 mm and a weight of approximately 180 g/m. For this diameter, corrugated tube is selected: for 3×2.5, a corrugated tube with a diameter of 16 or 20 mm is needed, taking into account a fill factor of no more than 40%. For 5×10, a 32 mm corrugated tube will be required. These figures do not depend on the ng index, as the sheath thickness changes slightly. A comparison of copper and aluminium conductors, which also affects load and weight, is given in the article copper cable.

Installation, laying in corrugated tube and bending radius

Both types are installed in the same way: stripping the sheath, preparing the conductors, connecting to terminals. The bending radius for VVG and VVGng is 7.5‑10 outer diameters depending on the cross‑section. For concealed wiring in corrugated tube, the version with the ng index is preferred, because in the event of a short circuit, the cable will not ignite neighbouring lines. The corrugated tube itself does not make the wiring fire‑safe — it only provides mechanical protection. If several cables without ng are laid in one corrugated tube, a fire in one will cause a chain reaction.

In timber houses, the requirements are even stricter: the cable must be in a metal pipe or in a corrugated tube with the ng‑LS index, and the wiring itself must be exclusively non‑combustible. Here, VVG without ng is unacceptable in any form. Outdoors and in the ground, VVGng is not used without additional protection, as PVC is degraded by ultraviolet light; for the ground, armoured VBbShv is used, or VVGng is laid in HDPE pipe.

When VVG without “ng” is sufficient

• Single laying in technical rooms with low fire load: boiler rooms, pumping stations, warehouses of non‑combustible materials.
• Open overpasses outside buildings where cables do not form dense bundles.
• Temporary networks on construction sites, if there is no risk of group fire.
• Power supply to individual consumers in a workshop, where the distance between routes excludes flame spread.
• Projects with a limited budget, where the designer consciously accepts risks and coordinates them with the fire supervision authority.

When VVGng is mandatory

• Residential multi‑storey buildings: risers, floor‑by‑floor distribution, apartment switchboards.
• Public buildings: schools, kindergartens, hospitals, shopping centres, offices with more than ten workstations.
• Escape routes: corridors, stairwells, foyers. Here, not just ng is required, but LS to maintain visibility during a fire.
• Group laying in trays, boxes, corrugated tubes where cables are laid closely together.
• Any facilities subject to State Fire Supervision: without the ng index, the project will not pass the expert review.

Typical mistakes when choosing and laying

• Buying VVG instead of VVGng for an apartment. The inspector will issue a directive and force the wiring to be replaced.
• Replacing VVGng‑LS with plain VVGng in a room with large numbers of people. Smoke from a fire will cut off visibility.
• Laying VVG in one corrugated tube with other cables in close contact. During a short circuit, the entire route burns out.
• Ignoring the bending radius: a sharp turn tears the sheath and insulation, even in the ng version.
• Choosing an undersized cross‑section on the assumption that an ng‑cable is “more powerful”. Ng does not affect current or power, only fire safety.
• Confusion in markings: PNG(A)-LS is a flat VVGng‑LS, not a separate cable type.

Frequently asked questions

What is the difference between VVG and VVGng?

VVG is a standard power cable with a PVC sheath; VVGng is the same cable but with a reduced‑flammability sheath, which does not propagate combustion during group laying.

Can VVG without “ng” be used in an apartment?

According to current regulations — no. SP 256.1325800.2016 requires cables with the ng index to be laid in residential buildings. The exception is single exposed wiring in utility rooms, but even there, the inspector may not approve it.

How is VVGng(A)-LS 3×2.5 deciphered?

V — PVC insulation, V — PVC sheath, G — without armour, ng(A) — does not propagate combustion according to category A, LS — low smoke emission. 3×2.5 — three copper conductors with a cross‑section of 2.5 mm².

How many kilowatts can VVGng 2.5 mm² handle?

About 5.9 kW on a 220 V single‑phase network and up to 15 kW on a 380 V three‑phase network with a symmetrical load. Exact figures depend on length and installation method.

Which corrugated tube should be chosen for VVGng 3×1.5?

The outer diameter of such a cable is about 8 mm. With a 40% fill margin, a 16 mm diameter corrugated tube will do. For denser laying — 20 mm.

What does LSLTx mean in the marking?

LS — low smoke emission, LTx — low toxicity of combustion products. This is an additional safety guarantee for people in the event of a fire.

Conclusion

VVG and VVGng are not just two letters of difference, but two levels of fire safety. Electrically, they are identical and are installed according to the same rules, but the use of VVG without “ng” is limited to technical zones. In residential and public buildings, in group laying, on escape routes, VVGng with the appropriate LS index becomes not a recommendation but a legal requirement. Saving on this index costs more — from directives to real damage in the event of a fire. When choosing between VVG and VVGng, the focus should be not on price, but on regulations and the value of human life.