Construction
Panel Load Fill Calculator
Add up existing breakers and see how much room you have for new circuits before service upgrade.
Available headroom
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- Demand load
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- % of main
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- New circuits OK?
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FAQ
Sum of breakers > main, is that OK? +
Yes! Diversification factor — not all circuits run at full load simultaneously. Code does not limit breaker sum, only the calculated load.
When to upgrade service? +
When calculated load (NEC 220) exceeds main rating, or when you keep tripping the main. Modern reality: EV + heat pump usually needs 200A+.