Busbar ampacity calculator
Two tools: choose a braided connector for your current, and calculate the current rating of a flat copper or aluminium busbar.
01 · PG selection
Set the current. See the connector.
1,000
Type a value, drag, or use the slider
Braided connector
PG80
up to 1,038 A · 280 mm² · contact 80 × 80 mm · S 9.5 mm
DC guide values from the PG table, IZAR catalogue 2024
02 · Flat busbar
How much current can the busbar carry?
Enter the size and temperatures. The result updates as you type.
DC current rating
A
Cu 120 × 10 mm, 40 → 90 °C
Heat dissipated per metre
- Convection Qc
- 81.1 W/m
- Radiation Qr
- 34.3 W/m
- Resistance R
- 18.18 µΩ/m
- Cross-section A
- 1,200 mm²
From the IZAR tables for this current
Copper braid
PG 150
up to 2,657 A · 1,080 mm² · B 150 · S 17 mm
Ask about PG 150Laminated copper
PE 121
up to 2,520 A · 1,200 mm² · B 120 · S 10 mm
Ask about PE 121Copper busbar
SM 1210
up to 2,520 A · 1,200 mm² · B 120 · S 10 mm
Ask about SM 1210
Smallest type from the 2024 catalogue tables for the DC current. PE and SM are recalculated for the temperatures entered; at 40/90 °C they are the table values.
PG: table values at 40/90 °C. For other conditions, confirm the selection with IZAR.
03 · Method
How it is calculated
A busbar loses heat by convection and radiation. Its current rating is the current at which the heat generated in its resistance equals the heat it gives off at the set busbar temperature.
- Qc = 1.38 · ΔT1.25 / H0.25 · P
- Qr = 5.67 · 10−8 · ε · P · (T14 − T24)
- R = ρ20 · (1 + α · (T − 20)) / A
P: perimeter 2·(w + t), H: width w, A: cross-section w·t, ΔT: temperature rise, T₁ and T₂: busbar and ambient temperature in K, ρ₂₀: resistivity at 20 °C from % IACS, α = 0.00393 · IACS/100 [1/K], T: busbar temperature in °C; w, t, H and P in metres.
Got a result? Send an enquiry.
Give us the code, current, length and quantity, or send a drawing. Our sales team will prepare a quote.