Single‑core vs multi‑core power cable: which one to choose for a house, workshop and main lines
When designing a distribution network, a dilemma always arises: to take several single‑core conductors or one multi‑core cable. The choice directly affects the labour intensity of installation, the final cost and the reliability of the line. In this article, based on the 7th edition of the PUE, GOST 22483 and GOST 31996, we compare the two designs and give guidelines for different situations.
A single‑core power cable is a single insulated conductor in a sheath. A multi‑core power cable combines several such conductors under a common sheath. Each solution has its own strengths: one wins in flexibility and compactness, the other in current ratings and repairability. Let us immediately outline the key differences in the table, and then we will look into the details.
Key differences between single‑core and multi‑core cables
| Parameter | Single‑core | Multi‑core |
| Number of cores | 1 | 2, 3, 4, 5 |
| Flexibility | Lower; large cross‑sections require special tooling | Higher, especially for models with class 5 cores |
| Heat dissipation | Better when laid separately | Mutual heating of cores reduces the permissible current |
| Inductive reactance | Depends on the phase layout scheme | Symmetric due to stranding |
| Installation of a three‑phase line | Requires laying several cables | One line ready for connection |
| Repair | Replacement of one phase without dismantling the entire route | In case of through damage, the whole cable is replaced |
Design and regulatory framework
According to GOST 22483, conductors are divided into flexibility classes: 1 — solid, 2 — stranded, 5 — highly flexible. Single‑core cables are produced with conductors of classes 1 and 2; multi‑core cables more often have class 2 conductors, and in flexible grades — class 5. That is why a multi‑core cable with a stranded conductor is valued where mobility and resistance to kinking are important.
Multi‑core designs are standardised by the number of cores: 2, 3, 4 or 5. A four‑core cable — three phase conductors and a neutral — was the basis of the old Soviet four‑wire marking for 0.4 kV networks. Today, this configuration remains the most demanded, and when earthing is required, a five‑core conductor is used. More about the design and classification is described in the article about power cables.
Design parameters according to GOST 22483
| Characteristic | Single‑core | Multi‑core |
| Flexibility class of cores | 1, 2 | 2, 5 (for flexible) |
| Cross‑section, mm² | 1.5–1000 | 0.5–240 |
| Stranding of cores | None | Mandatory, with filling of gaps |
| Presence of screen | Individual | Common or individual screens |
Electrical characteristics and current ratings
At alternating current, in a solid conductor of large cross‑section, the skin effect is noticeable: the current is displaced to the edges, the effective resistance increases. Stranding several conductors in a multi‑core cable partially compensates for this phenomenon. However, the close arrangement of insulated conductors causes mutual heating, therefore the permissible continuous current for a multi‑core cable, according to the PUE tables, is 10‑20% lower than the sum of currents of the same number of separately laid single‑core cables.
Voltage losses in a multi‑core line are stable and symmetrical across phases. Single‑core cables, if laid in a plane, give different phase inductive reactances, which, with uneven load, leads to voltage imbalance. For three‑phase circuits, a ready‑made four‑core cable is often taken, for example, three‑phase copper 4×4 or copper 4×6 VVGng.
Electrical parameters
| Parameter | Single‑core | Multi‑core |
| Skin effect | More pronounced | Reduced due to stranded structure |
| Permissible current for equal cross‑section | Higher (for single laying) | Lower due to mutual heating |
| Symmetry of inductive reactance | Depends on laying scheme | High, stranding equalises parameters |
| Voltage losses | Asymmetrical with incorrect laying | Symmetrical |
Installation and ease of laying
A rigid single‑core cable of large cross‑section is difficult to bring into a switchboard or bend with a small radius. According to the PUE, the bending radius for unarmoured single‑core conductors is at least 10 outer diameters. For multi‑core this figure is 7.5 diameters. A flexible multi‑core cable, for example, copper flexible KG 5x4mm², can be installed even in confined spaces and withstands repeated bending.
For mobile connection of machine tools, cranes, welding posts, single‑core conductors are unsuitable — they quickly break. Here, flexible copper grades KG and KGN lead. For fixed internal wiring in buildings, multi‑core VVG and VVGng are more compact: one sheath replaces several separate cables, less fasteners and cable trays are required. Recommendations for installation, taking into account bending radii and fixing methods, are given in the review cable laying.
Installation properties
| Criteria | Single‑core | Multi‑core |
| Minimum bending radius | 10 D | 7.5 D (unarmoured) |
| Ease of bringing into switchboard | Requires space, special tools | Easier, compact bundle |
| Mobile application | Not allowed | Allowed for flexible grades |
| Number of fixings | More (for each cable) | Less (one route) |
Cost and project economics
A linear metre of a single‑core conductor is cheaper than a multi‑core one. But for a three‑phase network, at least three such cables are required, plus a neutral and earthing conductor. As a result, the costs for fasteners, trays and electricians’ work often outweigh the initial savings. A multi‑core cable, such as copper 4×16, is purchased as a single drum and laid as one line, which reduces installation time.
Flexible versions — copper 4×16 flexible — add convenience when connecting, but also cost a little more. At large sites, a combined approach is often used: main lines are made with single‑core aluminium cable, and distribution networks inside buildings are made with multi‑core copper. A detailed comparison of conductor materials is given in the article comparison of aluminium and copper conductors.
Economic comparison
| Cost item | Single‑core | Multi‑core |
| Price per metre | Lower | Higher |
| Total line cost | Often higher due to number of cables and installation | Often lower |
| Consumption of fasteners and trays | Higher | Lower |
| Labour intensity of connection | Higher (stripping each cable) | Lower |
Reliability and service life
A solid core of a single‑core cable is stronger in tension than a bundle of thin wires, but it also transmits vibration to the contact clamps more rigidly. This weakens the connections over time. A flexible multi‑core cable dampens mechanical vibrations, therefore in workshops with operating machine tools preference is given to copper multi‑core conductors.
From the point of view of repairability, a single‑core line is simpler: in case of insulation breakdown on one phase, it is enough to replace the damaged section of that cable. In a multi‑core cable, with through damage to the sheath, the whole bundle suffers, and the cable is replaced entirely. However, modern sheaths made of PVC compound or cross‑linked polyethylene have high mechanical strength, and such incidents are extremely rare when the PUE requirements are observed.
What to choose in different situations
| Task | Preferred design | Justification |
| Apartment wiring | Multi‑core copper VVGng | Compactness, compliance with SP 256.1325800 |
| Power supply to a heavy machine | Single‑core copper or aluminium | Large cross‑sections, excellent heat dissipation |
| Mobile compressor | Multi‑core flexible KG | Resistant to reeling and vibration |
| Underground entry to a house | Multi‑core armoured VBbShv | One trench, full mechanical protection |
| 0.4 kV overhead line | Single‑core SIP or AVVG | Low weight, easy tensioning |
| Workshop with vibrating equipment | Multi‑core copper flexible | Vibration damping, reliable contacts |
| Trunk line TP – main switchboard | Single‑core aluminium | Metal saving, convenient unwinding |
| Riser of a multi‑storey building | Multi‑core VVGng LS 5×16 | Fire safety, one line per floor |
Conclusion
Single‑core power cable is the choice for high currents, open overpasses and tasks where repairability comes first. Multi‑core power cable is more convenient in household and commercial wiring, for mobile connections and where compactness and installation speed are important. When making a decision, rely on the requirements of the PUE, the permissible load tables of GOST 31996 and actual operating conditions.
The range of multi‑core power cables is presented in the catalogue — copper stranded. Aluminium versions, including armoured ones, are collected in the section aluminium power cable. A well‑designed and properly installed line will last for decades, no matter which type of cable is chosen.
