Which flexible busbar do I need?

Enter the current your bar carries for 30 minutes or longer and how it is installed. We compare the 200A, 350A and 500A max bars and point you to the smallest one that fits. You pick the length on the next page.

Your continuous current
A

The steady load, not a short surge. Surges up to the bar's Max rating for a few minutes are fine.

Air at the bar

Use the air right next to the bar. Inside a busy closed box it often runs 10 to 20 °C above the room.

The bar bolts to

If either end is on a cell terminal, pick cell terminals.

Bars side by side

Bars on the same circuit sharing the current. Stacked bars act like one thicker bar and carry less than spaced ones. Spaced means a gap of at least one bar thickness.

Orientation

Lying flat on a tray, plate or another part traps heat under the bar.

How we work this out

A busbar's current rating is how much it heats up above the air around it. The hottest the bar may run is set by what it bolts to: 75 °C for fuse, breaker and lug terminals, and about 60 °C for cell terminals. That limit minus the air temperature is the allowed rise, and we read the bar maker's published temperature-rise data at that rise, following the data's curve between its columns. We allow 1 °C over the terminal limit, about the accuracy of a good thermometer, which adds 1 to 3 %. Air below 25 °C gets no extra credit, results never go above the bar's Max rating, and everything is rounded down to the nearest 5 A. Length and hole size are not part of this.

Where the bar runsBarTo fuse, breaker or lugOn cell terminals

Single bar on edge. * Below the catalog data, extrapolated. 2 spaced apart ×1.72 and 3 spaced apart ×2.25 total (bar maker's data); 2 stacked ×1.46 total (from the maker's data for thicker bars); lying flat ×0.80 (our allowance).

Disclaimer: For reference only. Do proper engineering to determine your requirements and always follow applicable code.
Assumes clean, tight bolted joints. Layout factors are estimates.