How many kW can 2.5 mm² carry and which MCB do you need? The answer is in the load table, or ask us.
How to choose an electrical cable: type, cross-section, length and protection
A cable is determined by four things: where it will be laid (type), what load (current and cross-section), how long the line is (voltage drop) and what protection (MCB, residual current device). Below are the tables and charts that both installers and buyers use to make the decision.
Information and selectionSuitable / benefit⚠ Check⚡ Safety and mistakes
⚠ The tables and charts are for guidance only and may contain errors or inaccuracies. Before buying and installing, check against the equipment manufacturer's instructions, applicable regulations and the electrical design.
UAB „Elektrotechnikos sprendimai“ accepts no liability for errors or inaccuracies in the tables and charts or for decisions made on their basis. Cable and protection selection and installation must be carried out by a qualified electrician.
Benefit: a correctly selected cable does not overheat, does not pass excessive voltage drop to the load and is matched to the MCB. This is the cheapest place to save – replacing a plastered-in cable later costs far more than a metre of a larger cross-section.
Cable and wire types – how they differ
The letters in the designation describe the construction. According to the harmonised designation (HD 361): H – harmonised type, 03 / 05 / 07 – 300/300 V, 300/500 V, 450/750 V, V – PVC, V2 – PVC up to +90 °C, Z1 – halogen-free insulation, U / R / K / F – solid, stranded rigid, flexible (for installation), flexible (for moving appliances).
⚠ Check: * The rated voltage of CYKY-L depends on the manufacturer (e.g. AB „Lietkabelis“ CYKY-L – 450/750 V; other manufacturers' CYKY – 0.6/1 kV) – exact data are given on each product page. Single-core wires without a common sheath are laid only in conduits, trunking or panels. For the construction and purpose of BVV series cables, see the product pages in their subgroups.
Load table: power (kW) → current (A) → cable and protection
The most common household, farm and business loads. Current calculated: single-phase I = P / 230 V, three-phase I = P / (√3 × 400 V); for the motor cos φ = 0.85 and efficiency 0.87 are assumed. Cable cross-section – for a short route (up to ~20–25 m) under normal installation conditions.
Load
Power
Supply
Current IB
Typical cable (Cu)
Protection
Note
LED lighting circuit
0.5 kW
230 V, 1-ph
2.2 A
3×1.5 mm²
B10
Room or floor luminaires
Socket outlet circuit
3.5 kW
230 V, 1-ph
15.2 A
3×2.5 mm²
B16 + RCD 30 mA
Kitchen, room sockets
Washing machine / dishwasher
2.2 kW
230 V, 1-ph
9.6 A
3×2.5 mm²
B16 + RCD 30 mA
Separate circuit for each
Water heater (boiler)
2 kW
230 V, 1-ph
8.7 A
3×2.5 mm²
B16 + RCD 30 mA
Storage, 80–150 l
Oven
3.5 kW
230 V, 1-ph
15.2 A
3×2.5 mm²
B16
Separate circuit
Induction hob – single-phase
7.2 kW
230 V, 1-ph
31.3 A
3×6 mm²
B32
Or three-phase connection ↓
Induction hob – three-phase
7.2 kW
400 V, 3-ph
10.4 A
5×2.5 mm²
B16 3P
Current shared across 3 phases
Sauna heater
9 kW
400 V, 3-ph
13 A
5×2.5 mm²
B16 3P
Heat-resistant cable at the heater
Electric heater / heat pump backup heater
9 kW
400 V, 3-ph
13 A
5×2.5 mm²
B16 3P
As per equipment instructions
EV charger 7.4 kW
7.4 kW
230 V, 1-ph
32 A
3×6 mm²
C32 + RCD (A/EV or B)
Long route – 3×10
EV charger 11 kW
11 kW
400 V, 3-ph
15.9 A
5×2.5 / 5×4 mm²
C16 3P + RCD (A/EV or B)
5×4 – when route > ~25 m
EV charger 22 kW
22 kW
400 V, 3-ph
31.8 A
5×6 / 5×10 mm²
C32 3P + RCD (A/EV or B)
5×10 – when route > ~30 m
Three-phase motor, pump 5.5 kW
5.5 kW
400 V, 3-ph
10.7 A
4×2.5 / 5×2.5 mm²
Motor protection 10–16 A
Starting current 5–7 times higher
Garage, workshop (three-phase)
22 kW
400 V, 3-ph
31.8 A
5×6 / 5×10 mm²
C32 3P
Long route – 5×10
⚠ The tables and charts are for guidance only and may contain errors or inaccuracies. Before buying and installing, check against the equipment manufacturer's instructions, applicable regulations and the electrical design.
UAB „Elektrotechnikos sprendimai“ accepts no liability for errors or inaccuracies in the tables and charts or for decisions made on their basis. Cable and protection selection and installation must be carried out by a qualified electrician.
⚠ Important: the table is indicative. For EV chargers, saunas, heat pumps and motors always follow the equipment instructions (required MCB, RCD type, cable). For long routes, grouped cables or thermal insulation the cross-section is increased – see the tables below.
KibirkštisA 7.2 kW hob. Single-phase needs 3×6 and 32 A, but three-phase is fine with 5×2.5 and 16 A?
FazėYes. 7.2 kW on one phase is about 31 A; split across three phases it is about 10.4 A per phase. That is why a three-phase connection allows a thinner cable and a smaller MCB. Just check how the manufacturer allows the hob to be connected.
MCB → permissible power → minimum copper cross-section
How much power can be connected through a given MCB and the minimum cable required. Power calculated at cos φ = 1 (heaters, boilers, cookers). Cross-section selected by the condition In ≤ Iz, method B2 (cable in conduit or trunking), copper, PVC, +30 °C; for circuits from 16 A – at least 2.5 mm².
MCB In
Power 230 V, 1-ph
Power 400 V, 3-ph
Min. Cu cross-section 1-ph (B2)
Min. Cu cross-section 3-ph (B2)
6 A
1.4 kW
4.2 kW
1.5 mm²
1.5 mm²
10 A
2.3 kW
6.9 kW
1.5 mm²
1.5 mm²
13 A
3 kW
9 kW
1.5 mm²
1.5 mm²
16 A
3.7 kW
11.1 kW
2.5 mm²
2.5 mm²
20 A
4.6 kW
13.9 kW
2.5 mm²
2.5 mm²
25 A
5.8 kW
17.3 kW
4 mm²
4 mm²
32 A
7.4 kW
22.2 kW
6 mm²
6 mm²
40 A
9.2 kW
27.7 kW
10 mm²
10 mm²
50 A
11.5 kW
34.6 kW
10 mm²
16 mm²
63 A
14.5 kW
43.6 kW
16 mm²
25 mm²
80 A
–
55.4 kW
–
25 mm²
100 A
–
69.3 kW
–
50 mm²
125 A
–
86.6 kW
–
design
⚠ The tables and charts are for guidance only and may contain errors or inaccuracies. Before buying and installing, check against the equipment manufacturer's instructions, applicable regulations and the electrical design.
UAB „Elektrotechnikos sprendimai“ accepts no liability for errors or inaccuracies in the tables and charts or for decisions made on their basis. Cable and protection selection and installation must be carried out by a qualified electrician.
The rule every electrician checks: IB ≤ In ≤ Iz – load current ≤ MCB rated current ≤ cable current-carrying capacity. The MCB protects the cable, not the appliance: if the cable is thinner than the MCB allows, it will overheat before the MCB trips. For motors cos φ is usually 0.8–0.9, so the real power connected through the same MCB is lower, and the starting current is several times higher.
Current-carrying capacity by installation method
Chart. Same cross-section – different current-carrying capacity: a cable heats up as much as it cannot dissipate heat (IEC 60364-5-52)
Full table – copper, PVC insulation, conductor temperature +70 °C, ambient +30 °C (underground +20 °C, soil thermal resistivity 2.5 K·m/W), single circuit. B2 – multi-core cable in conduit on a wall or in trunking, C – cable directly on a wall or ceiling, D1 – cable in a duct underground. 1-ph – 2 loaded cores, 3-ph – 3 loaded cores.
Cu, mm²
B2 · 1-ph
B2 · 3-ph
C · 1-ph
C · 3-ph
D1 · 1-ph
D1 · 3-ph
1.5 mm²
16.5 A
15 A
19.5 A
17.5 A
22 A
18 A
2.5 mm²
23 A
20 A
27 A
24 A
29 A
24 A
4 mm²
30 A
27 A
36 A
32 A
37 A
30 A
6 mm²
38 A
34 A
46 A
41 A
46 A
38 A
10 mm²
52 A
46 A
63 A
57 A
60 A
50 A
16 mm²
69 A
62 A
85 A
76 A
78 A
64 A
25 mm²
90 A
80 A
112 A
96 A
99 A
82 A
35 mm²
111 A
99 A
138 A
119 A
119 A
98 A
50 mm²
133 A
118 A
168 A
144 A
140 A
116 A
⚠ The tables and charts are for guidance only and may contain errors or inaccuracies. Before buying and installing, check against the equipment manufacturer's instructions, applicable regulations and the electrical design.
UAB „Elektrotechnikos sprendimai“ accepts no liability for errors or inaccuracies in the tables and charts or for decisions made on their basis. Cable and protection selection and installation must be carried out by a qualified electrician.
⚠ Correction factors: cables in a bundle or tray heat each other – for three adjacent circuits the current-carrying capacity drops by about 30 %. A cable in thermal insulation (method A) dissipates heat worst. Higher ambient temperature also reduces Iz. In such cases one size larger cross-section is chosen or a design calculation is made.
Length and voltage drop
On a long line part of the voltage stays in the cable: motors start harder, luminaires flicker, chargers reduce power. For a final circuit the voltage drop should not exceed 3 % (lighting) – 5 % (other loads).
Chart. The longer the line, the larger the cross-section needed, even with the same MCB (1.5 mm² for comparison only: it is not used with a 16 A MCB)
Indicative maximum line length for ΔU ≤ 3 % with the load equal to the typical MCB current:
Cu cross-section
Load (= typical MCB)
230 V, 1-ph – up to
400 V, 3-ph – up to
1.5 mm²
10 A
≈ 23 m
≈ 46 m
2.5 mm²
16 A
≈ 24 m
≈ 48 m
4 mm²
20 A
≈ 31 m
≈ 62 m
6 mm²
32 A
≈ 29 m
≈ 58 m
10 mm²
40 A
≈ 38 m
≈ 77 m
16 mm²
50 A
≈ 49 m
≈ 99 m
25 mm²
63 A
≈ 61 m
≈ 122 m
⚠ The tables and charts are for guidance only and may contain errors or inaccuracies. Before buying and installing, check against the equipment manufacturer's instructions, applicable regulations and the electrical design.
UAB „Elektrotechnikos sprendimai“ accepts no liability for errors or inaccuracies in the tables and charts or for decisions made on their basis. Cable and protection selection and installation must be carried out by a qualified electrician.
Example: socket line 3×2.5 mm², 30 m, 16 A → ΔU = 2 × 30 × 16 × 0.0225 / 2.5 ≈ 8.6 V (≈ 3.8 %) – more than 3 %. With 3×4 mm²: ≈ 5.4 V (≈ 2.3 %). For such a route a larger cross-section is worth choosing. Formulas: single-phase ΔU = 2·L·I·ρ / S, three-phase ΔU = √3·L·I·ρ / S; ρ ≈ 0.0225 Ω·mm²/m (copper, +70 °C), aluminium ≈ 0.036 Ω·mm²/m.
Copper or aluminium?
Criterion
Copper (Cu)
Aluminium (Al)
Resistivity at +20 °C
≈ 0.0175 Ω·mm²/m
≈ 0.0282 Ω·mm²/m (≈ 1.6 times higher)
Cross-section for the same current
baseline
≈ 1 size larger (e.g. Cu 10 → Al 16 mm²)
Smallest cross-sections
from 1.5 mm²
for power lines usually from 16 mm²
Connections
standard terminals
only terminals marked Al or Cu/Al, contact paste, tightening control
Typical use
indoor installation, final circuits, panels
service entries, mains, long underground routes
Price
higher
lower for large cross-sections
⚡ Safety: aluminium and copper must not be connected directly in one terminal without dedicated connectors – due to galvanic corrosion and thermal expansion the contact weakens, heats up and may cause a fire.
⚠ What to check before buying
KibirkštisBefore buying I always check these things – it saves both money and a second trip to the site.
What to check
Why it matters
Supply: 230 V or 400 V
1-ph – 3 cores (L, N, PE); 3-ph – 5 cores (L1–L3, N, PE); 4 cores – only without neutral
Load power and current
Determines the cross-section and MCB (see the load table)
Line length
A long route needs a larger cross-section due to voltage drop
Installation location and method
Indoor, outdoor, underground, in conduit, bundled, in thermal insulation – changes the type and Iz
Building requirements
Halogen-free cables may be required in public buildings and escape routes
Conductor type and terminals
Stranded or flexible conductors in screw terminals – use ferrules
Connection allowance
Add 0.5–1 m for each end to the measured length
✗ Most common mistakes
✗ Mistake
Consequence
✓ Correct way
1.5 mm² for sockets with a 16 A MCB
The cable runs at or above its limit for long periods, insulation ages
3×2.5 mm² + B16, or 1.5 mm² + B10
2.5 mm² for a 50 m route to a garage
High ΔU, motors and compressors start with difficulty
Calculate ΔU, choose 5×6 – 5×10 mm²
4-core cable when there will be single-phase loads
No neutral – a new cable has to be laid
5-core cable for a three-phase circuit
NYM-J buried in the ground
The sheath is not designed for this – moisture, damage
Underground – CYKY-L with protection and warning tape
Single-core H07V-K without conduit
No mechanical protection – risk of damage
Only in conduit, trunking or a panel
⚡ Cu and Al directly in one terminal
Contact overheats – fire risk
Cu/Al connectors, Al-rated terminals
⚡ 2-core cable for a socket or metal appliance
No PE – electric shock hazard
3-core cable with PE and 30 mA RCD
⚡ Safe installation – Fazė's advice
FazėA good cable won't help if it is installed in a hurry. These points protect against faults and electric shock.
Before work, disconnect the supply, secure it against accidental reclosing and verify that no voltage is present.
Protect socket and wet-room circuits with a 30 mA residual current device (RCD).
Lay PVC cables at no lower than −5 °C; do not bend more sharply than the manufacturer allows.
Underground – sand bedding, mechanical protection and warning tape; through walls and risers – a protective duct.
Before energising a new line, measure the insulation resistance and check the continuity of the PE conductor.
Electrical installation work is carried out by an electrician with the appropriate qualification.
KibirkštisHow many kW can be connected to a 3×2.5 mm² cable?
FazėWith a 16 A MCB – up to 3.7 kW in a single-phase 230 V circuit. Three-phase 5×2.5 mm² with 16 A – up to 11 kW. On a long line or for a bundled cable the permissible load is lower.
KibirkštisWhich cable should I choose for a house service entry?
FazėAccording to the DSO connection conditions and the main breaker. For a three-phase 25 A entry, 5×10 mm² Cu or an equivalent aluminium cable is often used – the final cross-section is determined by length and design.
KibirkštisCan a cable be laid underground?
FazėYes, a cable designed for it (e.g. CYKY-L) – no shallower than 0.7 m, on sand, with mechanical protection and warning tape. NYM-J and single-core wires are not used underground.
KibirkštisWhat is the difference between H07V-K and H07V-U?
FazėBoth are 450/750 V single-core wires. H07V-K has a flexible stranded conductor (convenient in panels, requires ferrules), H07V-U has a solid rigid conductor (for fixed installation in conduit).
KibirkštisWhen is a halogen-free cable needed?
FazėWhen required by the design or fire safety conditions – most often in public buildings, escape routes, hospitals, schools. When burning it does not release corrosive halogen gases and produces less smoke.
KibirkštisCan the cross-section be chosen by power alone?
FazėNo. Power gives the current, but you must also consider the installation method (Iz), line length (ΔU) and the MCB (IB ≤ In ≤ Iz).
KibirkštisDo you sell by the metre?
FazėYes, we cut cables to the required length. For projects and larger quantities we prepare an individual quote.
Sources and assumptions (checked 2026-10-08): LST HD 60364-5-52 / IEC 60364-5-52 (current-carrying capacities, methods B2, C, D1, copper, PVC 70 °C); HD 361 (cable designation); HD 308 (core colours). The tables and charts are for guidance only and do not replace an electrical design; UAB „Elektrotechnikos sprendimai“ accepts no liability for their errors or inaccuracies.
Need cables for a project?
Send us the loads, lengths and installation conditions – we will select cables, protection and accessories and send a quote. We cut to length.
How many kW can 2.5 mm² carry and which MCB do you need? The answer is in the load table, or ask us.
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Copper photovoltaic interconnection ribbon | 1,2 × 0,20 mm | Sunwire LuvataCode: 1.2x0.20mm
