400-Amp Service Upgrade in Los Angeles: Do You Need It?

Most Los Angeles homes run fine on 200 amps. But add a second EV, a heat pump, an induction range, a pool heater and an ADU out back, and 200 amps stops being enough. That is when a 400-amp service upgrade comes up — and it is a very different project from a standard panel swap.

What a 400-Amp Service Actually Is

A 400 amp service is the size of the electrical feed coming from the utility to your home, not just the box on the wall. In residential work it almost never means one giant 400-amp panel. The standard build is a 400 amp meter main — a utility-rated meter enclosure with two 200-amp main breakers — feeding two 200-amp panels, or one main panel plus a subpanel for the garage, ADU or EV equipment.

It is also worth knowing that most residential 400-amp services are rated 320 amps continuous (often labeled 320/400). That is normal and code-compliant; the 400 figure is the peak rating.

Signs You Actually Need 400 Amps

Going to 400 amps is justified by load, not by square footage or wishful thinking. These are the situations where we most often size a Los Angeles home for it:

• Two or more Level 2 EV chargers running at 48A each, especially without load management
• Full electrification — heat pump HVAC, heat pump water heater, induction range, electric dryer — all at once
• A permitted ADU or garage conversion with its own kitchen, HVAC and subpanel
• Large homes (roughly 4,000+ sq ft) with multiple AC systems, a pool, and a workshop
• Adding a whole-home battery or standby generator on top of an already-loaded 200-amp service
• A licensed load calculation that lands above roughly 160-180 amps of continuous demand

If your list is shorter than that, a 200-amp service plus smart load management is usually the cheaper and faster answer. See our breakdown of 100-amp vs 200-amp service before assuming you need to go bigger.

The Load Calculation Comes First

Before any quote means anything, an electrician should run an NEC Article 220 load calculation on your actual appliances and planned additions. Los Angeles building departments require it with the permit application, and it is the only honest way to answer "do I need 400 amp service?" It frequently shows the opposite of what homeowners expect — plenty of homes that feel maxed out are actually sitting at 120-140 amps of demand and only need a panel upgrade, not a service upgrade.

What the Project Involves in Los Angeles

A 400 amp service upgrade touches the utility side of the system, so there are more moving parts than a straight panel replacement:

1. Load calculation, one-line diagram and permit application through LADBS (or the city building department in Pasadena, Burbank, Glendale or Arcadia).
2. Utility coordination and service planning with SCE, LADWP, PWP, BWP or GWP — they may need to upsize the transformer or service drop, which is often the longest lead time in the job.
3. Installation day: new 320/400A meter main, new service entrance conductors and conduit, upgraded grounding and bonding, and two 200-amp panels or a main plus subpanel.
4. City inspection, then a utility meter release and permanent reconnection.

Expect the whole process to run several weeks from permit to final sign-off, with the power actually off for roughly one day. Underground services, meter relocations and long conduit runs add time.

Cost Factors to Expect

Prices vary widely and any figure should be confirmed with a site-specific estimate, but these are the variables that move a 400-amp quote the most:

• Overhead versus underground service, and how far the meter sits from the utility connection
• Whether the utility has to upsize the transformer or run new conductors to the property
• Two-panel configuration, subpanel feeds, and how many circuits need to be re-terminated
• Trenching, stucco or masonry repair, and meter relocation
• Permit and inspection fees, which differ by city across the LA area
• Whether the existing grounding electrode system needs to be brought up to current code

A 400-amp service typically runs well over double a standard 200-amp upgrade because you are paying for utility-rated equipment, heavier conductors and two panels. Rebates that apply to panel work — including SCE programs tied to EV charging — change regularly and should be verified before you count on them.

400 Amps vs. Smart Load Management

Not every capacity problem needs a bigger service. Modern load management devices and smart panels can let two EVs, a heat pump and a range share a 200-amp service safely by staggering large loads. For many LA homeowners that is a fraction of the cost of a service upgrade and avoids utility delays entirely. It is worth pricing both paths — especially if the driver is EV charger installation rather than whole-home electrification.

Frequently Asked Questions

Do I need a 400-amp service?

Only if a load calculation says so. The common triggers are multiple Level 2 EV chargers, full electrification, a permitted ADU, or a large home with several AC systems and a pool. Otherwise a 200-amp service usually has room left.

What is the difference between 200-amp and 400-amp service?

200-amp service uses one main breaker and one panel. A residential 400-amp service uses a utility-rated meter main with two 200-amp mains feeding two panels, plus heavier service conductors and upgraded grounding. It is a utility-side upgrade, not just a bigger box.

Does a 400-amp upgrade mean two electrical panels?

Almost always, yes. Residential 400-amp equipment is normally built as a 400 amp meter main splitting into two 200-amp panels — for example one for the house and one for the garage, ADU or EV equipment.

How long does a 400-amp service upgrade take?

Plan on several weeks overall. Permitting and utility coordination take the most time; the physical installation is usually one day with the power off, followed by inspection and a meter release.

Can I upgrade to 400 amps without utility approval?

No. The service size is set with your utility, and the meter can only be released after a passed city inspection. Any contractor who offers to skip the permit or the utility step is putting your home and your insurance coverage at risk.

Talk to a Licensed LA Electrician First

911 Construction & Electric Inc. is a licensed, bonded and insured C-10 electrical contractor (CA Lic. #1027421) serving Los Angeles, Pasadena, Burbank, Glendale, Altadena, Arcadia and the San Fernando Valley. We will run the load calculation, tell you honestly whether 400 amps is warranted or whether a panel upgrade will do, and handle permits and utility coordination end to end. Request a free estimate or call 747-255-8595.