The key metric you need to consider for your wiring is the Minimum Circuit Ampacity (MCA). The MCA is the maximum current that a wire can carry continuously without exceeding its temperature rating. Start-up amperage is high when your mini-split first kicks in when it is likely to draw a...
Let’s say we have a 3.5-ton AC unit. That’s 42,000 BTU. If the EER rating is 10, it draws 4,200W of power when running at 100%. At 220V voltage, this means it draws 19.09 amps. We need to apply the 80% NEC rule, and we get the minimum breaker ampacity should be 23.86A...
Here is how to use this calculator: You can use our example for a 150W 12V device. Slide the wattage slider to ‘150’ and you will get the calculated minimum required ampacity: 15.63A. Based on this min. ampacity, you can pick the correct size wire for this 12V circuit by consulting...