A first-pass read on what your service could take. Enter your service size and a peak-demand figure off a recent bill, and we’ll run the same NEC-220.87-style arithmetic the pros use — existing demand at 125% against your service rating — to estimate the headroom you have today.
Enter your service size and a peak-demand figure to see a first-pass headroom estimate.
New to the 125% rule? Here’s what an NEC 220.87 load calculation actually tells you.
It’s a fast way to see whether the headroom conversation is even worth having. Three things to keep in mind.
The estimate sizes new load the way NEC 220.87 does — your existing maximum demand at 125%, measured against the service rating — instead of a conservative nameplate tally.
The demand line on a statement is a starting point, not the 15-minute interval peak the code wants. Seasonality and coincident new load can move the answer either way.
A free capacity check turns your bills, utility data, and panel photos into a conservative headroom range and a permit-ready Headroom Passport — with the proof a utility, AHJ, or PE will ask for.