200A vs. 400A: Do You Need a Bigger Service?

Start with a load calculation

The electrical code sets out how to calculate a home's load: square footage, the fixed appliances, heating and cooling, and anything big that runs for hours at a time. That number, not the breaker count and not what the neighbor did, tells you whether 200A carries the house. We do the calculation before recommending anything, and you get to see it.

What pushes a Phoenix house past 200 amps

• A/C. The biggest load in any Valley home, and it runs for hours in summer. Two or three systems on one house adds up fast.
• EV chargers. A Level 2 charger is typically a 40 to 60 amp circuit, running for hours. Two cars doubles it.
• Pool and spa. Pumps, heaters (especially electric heat pumps and spa heaters), lighting and water features.
• All-electric appliances. Electric range, dryer, water heater, or a heat pump replacing gas.
• A casita, guest house or shop with its own A/C and kitchen.

When 200A is enough

A typical single-family home with one or two A/C systems, gas appliances and one EV charger usually fits on a properly laid-out 200A service. If you're out of breaker spaces rather than out of capacity, a new panel or a sub-panel fixes that without a bigger service.

When 400A makes sense

Large homes with multiple A/C systems, a pool and spa, a casita and more than one EV often calculate past 200A. So do homes going all-electric. A residential “400A” service usually uses a meter rated 320A continuous (the utility's CL320 class), and it is a bigger project: larger equipment, often engineered plans, and more utility review. Cities such as Scottsdale publish separate permit requirements for single-family services over 200 amps.

Cheaper alternatives worth asking about

• A sub-panel for the pool, casita or garage
• EV load management, which lets a charger slow down when the house is busy
• Moving a few loads rather than upgrading the whole service

We'll tell you when one of these saves you real money, and when it just delays an upgrade you'll pay for anyway.

Real examples

Our Olney Ave job is a 400A service with a 200A sub-panel for added load. Our Turney Ave job took an undersized, fused service to 200A. For pricing, see panel upgrade cost in Phoenix; for the utility side, SRP vs. APS.