Copper busbars for electrical energy transmission

Copper busbars – rigid electrolytic copper bars for switchboard main bars, PE and N bars, transformer substations, UPS and battery systems. 3–10 mm thick, 20–160 mm wide, 4 m long. Below the products: selection by current, weight table and installation tips.

Selection by current Aluminium busbars Flexible busbars Tinned busbars Busbar accessories

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Rigid copper busbars · electrolytic copper · 4 m lengths

Copper busbars | 20–160 mm | selection guide

Flat copper busbars for switchboard main bars, PE and N bars, transformer substations, UPS and battery systems. Below: busbar selection by current, the full range with cross-section and weight, and installation tips.

sizes in stock range

3–10 mm

bar thickness

20–160 mm

bar width

4 m

bar length

Asking: Kibirkštis – a young electrician who isn't afraid to ask. Answering: Fazė – an experienced engineer.

Key point:
A busbar is chosen not by price per kilogram but by its continuous current rating. This depends not only on the cross-section but also on the shape: a thinner, wider bar has a larger cooling surface. For example, 30 × 10 mm and 60 × 5 mm both have 300 mm², yet DIN 43671 rates them at 573 A and 688 A (60 × 5 mm is a DIN table example, not in our range) respectively. Mounting position, enclosure temperature and whether the bar is painted also matter.

Quick busbar selection by current

The smallest size in our range whose indicative DIN 43671 rating exceeds the stated load: one bare bar per phase, AC, ambient +35 °C, bar temperature +65 °C.

Load current	Smallest busbar	Current rating (DIN 43671)	Typical application
up to 160 A	20 × 3 mm	204 A	Small board phase bars, PE or N bar
up to 250 A	20 × 5 mm	274 A	Sub-distribution board
up to 400 A	40 × 5 mm	482 A	Building main board, 250 kVA transformer (~361 A)
up to 630 A	40 × 10 mm	715 A	400 kVA transformer, 0.4 kV side (~577 A)
up to 800 A	50 × 10 mm	852 A	500 kVA transformer (~722 A)
up to 1000 A	80 × 10 mm	1240 A	630 kVA transformer (~909 A)
up to 1250 A	100 × 10 mm	1490 A	800 kVA transformer (~1155 A)
up to 1600 A	120 × 10 mm	1740 A	1000 kVA transformer (~1443 A)
up to 2000 A	160 × 10 mm	2220 A	1250 kVA transformer (~1804 A)

⚠ Check: DIN 43671 values are indicative. A painted bar dissipates heat better (rating about 15–20 % higher), while a higher temperature inside a closed enclosure reduces it. Two parallel bars per phase do not double the rating – expect roughly 1.6–1.8 times. The final decision rests with the switchboard designer under IEC 61439, including short-circuit withstand.

Full range: dimensions, cross-section, weight

Click a size to open the product page. Weight is calculated with a copper density of 8.96 g/cm³.

Size (width × thickness, length)	Cross-section	kg/m	Bar weight, kg	DIN 43671, A	Code · manufacturer
20 × 5 mm, 4 m	100 mm²	0.90	3.6	274 A	ESV20X5 · Elsp Group
25 × 3 mm, 4 m	75 mm²	0.67	2.7	245 A	ESV25X3 · Elsp Group
25 × 5 mm, 4 m	125 mm²	1.12	4.5	327 A	ESV25X5 · Elsp Group
30 × 3 mm, 4 m	90 mm²	0.81	3.2	285 A	ESV30X3 · Elsp Group
30 × 4 mm, 4 m	120 mm²	1.08	4.3	–*	ESV30X4 · Elsp Group
30 × 5 mm, 4 m	150 mm²	1.34	5.4	379 A	ESV30X5 · Elsp Group
30 × 6 mm, 4 m	180 mm²	1.61	6.5	–*	ESV30X6 · Elsp Group
40 × 4 mm, 4 m	160 mm²	1.43	5.7	–*	ESV40X4 · Elsp Group
40 × 5 mm, 4 m	200 mm²	1.79	7.2	482 A	ESV40X5 · Elsp Group
50 × 5 mm, 4 m	250 mm²	2.24	9.0	583 A	ESV50X5 · Elsp Group
60 × 6 mm, 4 m	360 mm²	3.23	12.9	–*	ESV60X6 · Elsp Group
40 × 10 mm, 4 m	400 mm²	3.58	14.3	715 A	ESV40X10 · Elsp Group
50 × 10 mm, 4 m	500 mm²	4.48	17.9	852 A	ESV50X10 · Elsp Group
60 × 10 mm, 4 m	600 mm²	5.38	21.5	985 A	ESV60X10 · Elsp Group
80 × 10 mm, 4 m	800 mm²	7.17	28.7	1240 A	ESV80X10 · Elsp Group
100 × 10 mm, 4 m	1000 mm²	8.96	35.8	1490 A	ESV100X10 · Elsp Group
120 × 10 mm, 4 m	1200 mm²	10.75	43.0	1740 A	ESV120X10 · Elsp Group
160 × 10 mm, 4 m	1600 mm²	14.34	57.3	2220 A	ESV160X10 · Elsp Group

* This size is not listed in DIN 43671 – confirm the current rating with the manufacturer's data or ask us. Need another size or a project quantity? Write to us – we will send a quotation.

Where copper busbars are used

Distribution boards and MCCs
L1–L3, N and PE main bars, connections between the incoming switch-disconnector and circuit breakers.

Transformer substations
0.4 kV side connections, incomers to LV switchboards, earthing main bars.

UPS, batteries, solar plants
DC bars between batteries, inverters and DC boards, where currents are high and voltage is low.

Earthing and bonding
Main earthing bar, equipotential bonding bars in industrial and IT rooms.

Copper, aluminium or flexible busbar?

Busbar type	When to choose	What to consider
Rigid copper (this category)	Highest conductivity in a compact space, reliable bolted joints	More expensive and heavier than aluminium
Aluminium	Long runs and large cross-sections where cost and weight matter	Needs ~1.6 times the cross-section for the same resistance, plus Cu–Al transition joints
Flexible copper	Connections between devices, vibration, thermal expansion compensation	More expensive, suited to short connections
Tinned flexible	Damp or aggressive environments, joints with aluminium	Highest price
Busbar accessories	Supports, insulators, terminals, protective covers	Select by bar width and thickness

Installation: keep the joint cool

FazėA busbar rarely fails in the middle – it's the joints that overheat. So the key is preparing the contact surface and tightening correctly.

Clean contact surfaces to bare metal before jointing and apply contact (anti-oxidation) compound. Do not abrade tin-plated bars – cleaning and degreasing is enough.
Use property class 8.8 bolts with disc spring (Belleville) washers and tighten with a torque wrench to the manufacturer's specified torque.
Fix bars on insulated supports; set the support spacing according to the short-circuit current – long unsupported spans deform during a short circuit.
Bend only with a proper tool, observing the minimum bending radius for the bar thickness – a crack at the bend increases resistance.
On long runs and at device terminals use flexible connectors – they compensate for thermal expansion and vibration.
Mark the phases (L1, L2, L3, N, PE) and cover live bare parts with protective covers.

✗ Most common mistakes

Bar chosen by cross-section only, ignoring the temperature inside a closed enclosure – nearby devices and insulation overheat.
Joint without compound and disc spring washers – it loosens over time, resistance rises, the joint heats up.
Copper bar bolted directly to aluminium – galvanic corrosion, the joint burns out within a few years.
Two bars per phase counted as double current – in reality only ~1.6–1.8 times more.

Diagram: bolted busbar joint – wrong and correct

Diagram. Bolted busbar joint. The DIN 43671 current rating only applies when the joint adds no extra resistance. A poorly made joint runs hotter than the rest of the bar, oxidises and gets hotter over time. Left – the most common mistakes, right – the correct solution; the numbers match the notes in the diagram.

KibirkštisThe bar was sized from the table, yet the joint still runs hot. Why?

FazėUsually it is not the cross-section but the joint: too small an overlap, uncleaned surfaces or loose bolts. Connect it as shown on the right and check the loaded switchboard with a thermal camera after commissioning.

Bolted busbar joint – diagram: wrong and correct | elsprendimai.eu

☝ Click the diagram to open the enlarged version.

⚠ This diagram is for guidance only and may contain inaccuracies. Before connecting, check against the manufacturer's instructions and the device markings.
The qualified electrician carrying out the installation is responsible for it. UAB „Elektrotechnikos sprendimai“ accepts no liability for connections or possible errors.

What current means in kW

Indicative power by current: in a three-phase 400 V system P = √3 × 0.4 kV × I × cos φ ≈ 0.693 × I × cos φ kW, in a single-phase 230 V system P = 0.23 × I × cos φ kW. For motors cos φ is usually 0.8–0.9, so the real connected power is lower.

Load current	400 V, 3~, cos φ = 1	230 V, 1~, cos φ = 1
100 A	69.3 kW	23.0 kW
160 A	110.9 kW	36.8 kW
250 A	173.2 kW	57.5 kW
400 A	277.1 kW	92.0 kW
630 A	436.5 kW	144.9 kW
1000 A	692.8 kW	230.0 kW
1600 A	1108.5 kW	368.0 kW
2000 A	1385.6 kW	460.0 kW

FAQ

KibirkštisWhat copper are the busbars made of?

FazėElectrolytic tough pitch copper (Cu-ETP, EN 13601) – about 99.9 % Cu, conductivity about 58 MS/m, density 8.96 g/cm³.

KibirkštisCan a busbar be used for DC?

FazėYes. There is no skin effect with DC, so the rating is equal to or slightly higher than for AC. For battery and solar DC bars a wider bar is often chosen to reduce voltage drop.

KibirkštisHow do I size N and PE bars?

FazėThe N bar is usually the same cross-section as the phases – especially with non-linear loads (LED, inverters, UPS) that increase neutral current. PE is sized to IEC 60364-5-54: for phase cross-sections above 35 mm², usually at least half the phase cross-section.

KibirkštisHow much does a 4 m bar weigh?

FazėWeight = width × thickness × length × 8.96 g/cm³. For example, 100 × 10 mm × 4 m ≈ 35.8 kg – plan two people or a lifting aid.

KibirkštisCan a busbar be painted or insulated?

FazėYes. A painted bar dissipates heat better, and heat-shrink insulation protects against accidental contact. Leave the contact areas unpainted.

Copper busbars for switchboards and projects

We will help you size the busbar by current and supply supports, insulators and flexible connectors. For project quantities we prepare an individual quotation.

☎ +370 620 72733 ✉ info@elsprendimai.eu