XVB cable or VOB wire: differences and choice in Belgium

XVB is a sheathed cable; VOB is a single-core wire with basic insulation only. That leads to the key rule: you can install XVB surface-mounted, on a cable tray and directly in a wall chase; under AREI/RGIE, VOB belongs in electrical conduit or a closed trunking. Which product fits in the end depends on the route, the fire class and the actual data sheet, not on the price per metre.

What is XVB cable?

XVB has XLPE (cross-linked polyethylene) core insulation and a PVC outer sheath. A designation such as 3G2.5 means three 2.5 mm² cores, one of them a green-yellow protective conductor. Check the number of cores, the protective conductor and the cross-section on the data sheet of the chosen product. Nexans, for example, offers XVB as a CPR class Cca variant.

What is VOB wire?

VOB is a PVC-insulated single conductor. H07V-U has a solid conductor and H07V-R a stranded one, so VOB does not automatically mean flexible wire. Because the wire has only basic insulation, you install it in electrical conduit such as Preflex or in a suitable closed system. For H07V-U, Nexans states CPR class Eca.

Where can you install XVB and where VOB?

For embedding without conduit, subsection 5.2.9.10 requires horizontal runs 25 to 35 cm below the ceiling or above the floor, vertical runs as close as possible to a corner or 10 to 20 cm beside door frames, and at least 0.4 cm of plaster cover. Wiring embedded in concrete or cement needs at least 3 cm of cover. The complete system of installation methods is explained in Installation methods under AREI.

Which fire class do you need?

Section 5.2.7 limits fire propagation through the CPR class:

• Installed singly: at least property F1 or class Eca (subsection 5.2.7.2).
• In bundles or flat formation: at least F2 or class Cca (subsection 5.2.7.3).
• In building cavities and combustible trunking or skirting: also F2 or Cca (subsection 4.3.3.5 b).

Exemptions include cables and conduits embedded at least 3 cm deep in non-combustible cladding (subsection 5.2.7.1 no. 3). What counts is the class of the product actually supplied, according to its declaration of performance; the name XVB or VOB alone does not fix it.

Comparing costs properly

A metre of 3G2.5 cable cannot be compared with a metre of a single 2.5 mm² wire. Compare quotes for the same route, the same number of conductors and the same work. VOB in conduit has one clear advantage: wires can be replaced or added later, because they must remain pullable at all times (5.2.9.3). The comparison Preflex or open wiring covers this in detail.

Cross-section and protection

The cable type does not replace sizing. Load, length, installation method and voltage drop determine the cross-section; Table 4.11 limits the breaker. The mapping is in Cable cross-section by circuit breaker.

Documenting your choice

Record the cable type, cross-section, number of cores, installation method and route for every segment. If the installation method changes, for example from conduit to cable tray, the plan must show it. In PlanElec you store these details per cable; the self-check flags cables installed singly below Eca and cables in hollow walls below Cca without documented conduit. The on-site inspection is carried out by the accredited inspection body.

Sources checked on 5 October 2026

• Nexans — XVB Cca ULTIMO
• Nexans — H07V-U / H07V-R
• FPS Economy — AREI/RGIE Book 1, subsections 4.3.3.5, 5.2.7.1–5.2.7.3, 5.2.9.3, 5.2.9.5, 5.2.9.6, 5.2.9.9 and 5.2.9.10