200-Amp to 400-Amp Service Upgrade
Most homes never need 400-amp service. The ones that do are stacking an ADU, EV chargers, a heat pump, and a pool on a panel that is finally maxed out. We run the load calculation first, then build it the right way and own the SCE coordination from start to finish.
What a 400-Amp Service Upgrade Is
A 200-amp to 400-amp service upgrade replaces your 200-amp service with what the power company calls 400-amp service. In a home, that is almost always a 320/400-amp class service, a meter rated for 320 amps continuous and 400 amps non-continuous, usually wired as a 400-amp meter main feeding two 200-amp panels. That two-panel build is more reliable, often cheaper than one giant 400-amp panel, and far easier to feed an ADU or EV subpanel from. Panels and service upgrades are all we do at The Panel Pros, so we can size this honestly and tell you when you do not actually need it.
What a 400-Amp Service Upgrade Includes
A 400-amp upgrade is a bigger job than a standard 200-amp swap, and every one we do is a complete, permitted, inspected, utility-coordinated service change. Here is what comes with it.
Before we quote a 400-amp anything, we run a load calculation per NEC Article 220 to prove your 200-amp service is genuinely maxed out. If a clean 200-amp upgrade and a planned subpanel will do the job, we tell you that instead.
We install a 320/400-amp class meter main as the service point, the standard residential setup that the utility refers to as 400-amp service, built to current code at the connection.
Most of the time we feed two 200-amp panels off the meter main rather than a single 400-amp panel, because that layout is more reliable, usually less expensive, and leaves clean room to add an ADU or EV subpanel later.
A 400-amp service needs heavier service entrance conductors and a grounding and bonding system to match, so we upsize the wire and bring the grounding electrode system up to today's California Electrical Code.
We pull the city electrical permit, coordinate the Southern California Edison meter release and any site evaluation with you, and handle the final inspection from start to finish.
South OC homes are almost all stucco, so the scope includes patching the exterior cleanly where we open the wall, not leaving you with a hole to deal with.
Book a free on-site assessment. We give you a flat-rate price in writing, with no obligation.
Signs You Need a 400-Amp Service Upgrade
A 400-amp service is rare and most homes never need it. These are the situations where it is genuinely worth a load calculation.
- Your 200-amp panel is already full and a real load calculation shows no spare capacity
- You are stacking an ADU plus Level 2 EV chargers plus a heat pump on one service
- You added a pool or spa, a heat pump water heater, and induction cooking
- You have a large or luxury home, often in the 3,000 to 4,000-plus square foot range with multiple zones
- You are building an ADU that pushes combined demand past 200 amps
- You run a workshop or shop with heavy machinery or specialty equipment
- You have multiple subpanels and are still running out of room
Permits, Inspection, and the SCE Meter Release
A 400-amp service upgrade is a permitted, inspected, utility-coordinated job, and the part homeowners dread, the power company, is the part we own. Every South Orange County city issues its own electrical permit through its building division, whether you are in Mission Viejo, San Clemente, Coto de Caza, or Newport Beach, and the California Electrical Code requires that permit any time you raise the amperage of a service. Permit fees are modest and vary city to city, and that cost is built into the flat-rate quote you approve. We pull it, not you.
The utility side is where a 400-amp job differs from a routine 200-amp swap. Nobody works on the utility side of the meter without authorization from Southern California Edison, and on a service this size SCE typically field-evaluates the property to confirm the existing transformer and service line can carry the added load before they energize it. We walk you through the meter release as the account holder and handle that conversation. Set the right expectation here. The panel work itself moves fast, but if SCE has to upsize the transformer or replace the service drop, that runs on a utility timeline of weeks to months that no contractor controls.
Once the new service is in, your city inspector verifies the meter main, the conductors, the grounding, and the working clearances all meet code, and some cities also require a meter spot or utility coordination step on site. We manage the permit, the SCE release, and the inspection end to end. If you are still deciding between sizes, our 200-amp panel upgrade page covers the more common path, which is the right call for most homes.
How a 400-Amp Service Upgrade Works
We come out, look at your service and every major load you have or plan to add, and run the load calculation that proves whether 400-amp is actually warranted or whether 200-amp will carry you.
You get one clear price in writing that covers the meter main, panels, conductors, permit, and inspection, with no surprise change orders once the job is underway.
We pull the city electrical permit and coordinate the Southern California Edison meter release and any service planning, so we know early if the utility needs to touch the transformer.
We install the 320/400-amp class meter main and feed the panels, then complete the changeover. Straightforward panel work moves quickly once SCE is lined up.
The city inspector verifies the work meets code, we handle the visit and show the SCE confirmation, and your new service is permanently energized.
What a 400-Amp Service Upgrade Costs
A 400-amp service upgrade costs well above a standard 200-amp upgrade, and the number swings hard with the home. Most jobs land in the $8,000 to $12,000 band, while complex work like an underground re-feed, a panel relocation, long runs, or SCE infrastructure can push past $15,000. The only number that means anything is the flat-rate written quote we give you after the free on-site load calculation, and we never cap or undercut a real one with a teaser price.
- Overhead versus underground service, since underground re-feeds and upsizing to 3-inch conduit drive the most cost
- Upsizing service entrance conductors and the grounding and bonding system to 400-amp
- Relocating the panel or meter to meet current working-clearance code
- Whether SCE has to upsize the transformer or replace the service line, which can more than double the cost and the timeline
- Trenching or boring through driveways, hardscape, and stucco walls
- A two 200-amp panel build versus a single oversized 400-amp panel
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Frequently Asked Questions
Do I actually need a 400-amp service
Probably not, and we would rather tell you that up front. A 200-amp service is plenty for the large majority of homes. A 400-amp service is genuinely warranted when a load calculation per NEC Article 220 shows your demand approaching or passing 200 amps, which usually means you are stacking an ADU, EV chargers, a heat pump, and a pool on one service. We run that calculation before we quote, and a lot of homes that ask about 400-amp really just need a clean 200-amp upgrade plus a planned subpanel.
Why does a 400-amp service use a 320-amp meter
Because residential 400-amp service is almost always a 320/400-amp class service. The meter is rated for 320 amps continuous and 400 amps non-continuous, and the power company calls it 400-amp even though the stamp reads 320. Best practice is to draw no more than about 80 percent of that rating continuously. It is the standard, code-correct way to build this, and we usually wire it as a 400-amp meter main feeding two 200-amp panels.
What will a 400-amp upgrade cost
It depends heavily on the home, so we use a wide range and never a single hard number. Most South Orange County jobs run about $8,000 to $12,000, with complex work passing $15,000. Underground re-feeds, conductor upsizing, relocation, and anything SCE has to do on the transformer are the big drivers. You get a flat-rate written quote after the free on-site load calculation, and our panel upgrade cost guide for Orange County walks through what moves the price.
How long does a 400-amp service upgrade take
The panel and meter work moves quickly once everything is lined up, but a 400-amp upgrade is not the kind of same-day job a standard 200-amp swap can be. If Southern California Edison has to upsize the transformer or replace the service drop, that runs on a utility timeline of weeks to months that is outside our control. We tell you early in the load calculation whether the utility is likely to be involved so there are no surprises.
Do I have to deal with Southern California Edison myself
You make the meter release request as the account holder, which is a quick step, and we handle everything around it. We coordinate the SCE meter release, the service planning, and any site evaluation SCE needs to confirm the transformer and service line can carry the new load. That coordination is part of the job and it is one of the headaches we take off your plate.
Should I get one 400-amp panel or two 200-amp panels
Two 200-amp panels off a 320/400-amp class meter main is usually the better build. A single 400-amp main-breaker panel can cost several times what two 200-amp panels cost, the two-panel layout tends to be more reliable, and it leaves clean room to add an subpanel for an ADU or EV charger later. We confirm the right layout for your home during the load calculation.
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