What main breaker means
The main breaker is the large breaker that shuts off power to the whole panel and protects the service conductors.
Also called main disconnect, service disconnect.
Where it matters on a electrical job
Its rating is the number people mean when they say a house has a certain amp service. Before adding big loads, a load calculation decides whether the existing main can carry them.
What the model code says
- Each service generally has one disconnecting means, and never more than six grouped together. (IRC 2021, Chapter 36)
Check which code edition your building department enforces for main breaker before you quote.
What it costs
Koira's electrical panel upgrade cost guide puts a typical job at $2,150, with most between $1,300 to $3,000. The guide shows its sources and what moves the price. The electrical load calculator prices a job line by line.
Work it out
- Free calculator: Electrical load calculator
- Cost guide: Electrical panel upgrade cost
- Licensing: Electrical license rules by state
- Tools, templates and guides: Free electrical resources
Sources: 2021 International Residential Code, Chapter 36, Services (ICC). Checked October 9, 2026.