Service Size (100 / 150 / 200 / 400 Amp)
The total amperage your home can draw from the utility, read off the main breaker. 100 amps was the postwar standard, 200 is today's default, 400 serves large or all-electric homes.
Service size is the budget everything else lives within, and electrification is what strains it: an EV charger (40 – 60 amps), a heat pump, an induction range and a hot tub can individually fit a 100-amp service but not together. The formal load calculation answers whether you need more; the panel label and main breaker say what you have.
Two nuances save money. First, service size and panel size are linked but distinct: some homes need a bigger panel (more breaker spaces) without more service. Second, smart load-management devices can shed an EV charger or dryer momentarily, letting some homes add big loads within 100 or 150 amps and defer the service upgrade entirely.
Talking to a contractor about this?
Run the project past a licensed electrical pro first. Calls are answered around the clock and routed to a pro serving your area.
- Weatherhead : The hooded fitting at the top of the service mast where overhead utility wires enter your home, shaped to keep rain out of the conduit running down to the meter.
- Meter Base (Meter Socket) : The enclosure the utility's electric meter plugs into, mounted on the outside of your home.
- Service Drop & Service Lateral : The two ways utility power reaches a home: a service drop swings overhead from the pole to the weatherhead; a service lateral runs underground to the meter.
- Disconnect (Emergency Disconnect) : A switch that cuts all power to a building or a piece of equipment.