Characterizing electrical panel capacity, breaker space, and loads in U.S. single-family homes

In this paper published the the Journal of Building Engineering, we provide foundational estimates of the electric infrastructure of single-family homes in the U.S. We provide nation-wide estimates of electricity panel capacity, available breaker space, and the headroom available in the panels. These estimates are important for determining the costs and grid impacts of adding new loads to single-family homes, and for grid planning and operations to ensure an affordable, safe, and reliable grid. 

We estimate existing panel capacity and breaker space by applying predictive models trained on field data to a representative database of homes (ResStock). We estimate that 100A and 200A panels are by far the most common sizes, representing 55% and 29% of the single-family panel stock respectively. Homes with larger electrical panels generally have more available breaker space, but at least 20% of panels of all sizes have no available breaker space.

We then estimate the amount of headroom available by household by simulating the National Electric Code load calculations that electrical contractors use to size electrical panels. These results indicate that many homes have the capacity to accommodate additional loads without expensive panel and electric service replacements. 

This open-access journal article was published in Journal of Building Engineering and can be downloaded here. A webinar discussing this research was recorded on April 2, 2026, and can be viewed here.