The electrician evaluates the grounding electrode system and corrects it as required by the installation, applicable code, and utility standards. Age alone does not automatically require replacement. Overhead and underground services also create different installation scopes, and the utility's requirements help determine the approved metering arrangement and service layout before equipment is ordered.

How the Project Moves Forward

The project begins with the load calculation and an on-site assessment. The electrician identifies the equipment that can remain, the work needed for the larger service, and the proposed panel locations.

Next come utility coordination and the required permit process. The serving utility must approve the larger service and the equipment used at the property — the electrician confirms the serving utility for the address, since this area is served by more than one power company. On the Northshore, for example, a property may be served by Cleco or by Washington-St. Tammany Electric. The AHJ handles permitting and inspection.

The electrician then plans the installation and cutover — the period when the old service is disconnected and the new service is connected. Any work that can be completed beforehand helps reduce disruption, but the outage plan needs to account for inspection and utility scheduling.

Where inspection is required, the necessary approval must be in place before the utility connects service. This order is a common rule across power companies, not one utility's preference: inspection approval comes before reconnection.

If anyone depends on electrically powered medical equipment, arrange backup power or another plan before the outage, and tell the electrician before scheduling.

How Long Will the Power Be Off?

The power is off during the cutover portion of the job. Some installation work may be completed before the outage to reduce disruption. Restoration can take longer if inspection or the utility's reconnect is delayed, so ask for the expected outage window and what happens if either slips.

Whether the household can remain comfortably at home depends on the outage duration and the household's needs. Confirm the planned cutover, inspection arrangements, and backup plan before work starts.

What Determines the Cost?

A service upgrade involves more than installing a larger panel. The quote should identify:

Meter equipment and service disconnects.
Service conductors and panel feeders.
Panel replacement or modifications.
Grounding-and-bonding work.
Overhead or underground installation work.
Permit, inspection, and utility-related charges, where applicable.
Access, routing, and repairs associated with the installation.

The useful comparison is the complete scope — not simply whether both quotes say \"400 amps.\" Equipment must also satisfy the serving utility's requirements.

The Safety, Code, and Repair Boundary

A homeowner can do useful homework: an honest inventory of the home's big loads — what runs at once, what is planned, what the wish list holds. That list is what the load calculation starts from.

Everything else belongs to a licensed electrician. This is service-entrance work: utility connections, a meter socket, feeders, main panels. It is permitted work, and it is inspected work where inspection is required. In Louisiana, the AHJ is responsible for the permit and approval process under the statewide Uniform Construction Code and local permit and inspection procedures. Inspection is performed under the jurisdiction's process, by its inspector or by a licensed private inspector working under contract with or registration in the jurisdiction. The AHJ answers what applies at that address.

The benefits of a licensed, experienced electrician on this project are practical: a load calculation that establishes whether more capacity is needed, utility approval before equipment is ordered, and coordinated installation, inspection, and reconnection.

What to Ask the Contractor

What does the load calculation show, and why is a larger service needed?
Which existing equipment can stay?
Who handles utility approval, permits, inspection, and reconnection?
What is the planned outage window, and what happens if reconnection is delayed?
Does the quote identify utility charges, installation work, and any repairs that are not included?

The goal is not simply to install equipment with a larger number on it. It is to provide the capacity the home needs, with an approved layout and a clear plan for getting the power back on.

Sources

Milbank Manufacturing, spec sheet for the U5890-X-2/200-BL: ringless meter socket rated 320 amperes continuous with two 200-ampere main breakers, up to 240V single phase, UL Listed — one published example of the split-load arrangement. Milbank's 320A meter-main catalog family also includes single-400A main-breaker arrangements at the same 320 amperes continuous class.
Cleco Power LLC, Electric Service Standards (cover June 2026; section pages September 21, 2026) (cleco.com): availability, service-entrance location, and point of delivery must be determined by consulting Cleco when planning new installations, changes, remodeling, or increases of load (Section 8.1); connectors in 320-amp meter sockets must accept up to 600 MCM for a single-wire connector or up to 350 MCM per lug for a dual-wire connector, and connectors must match the service-entrance size with never more than one wire per connector (Section 8.3.1); where local ordinances require inspection and approval, inspection is completed and the certificate secured before the Company renders service (Section 8.4).
Entergy, Customer Installation Standards (entergy.com): inspection approval before connection where inspection is required — stated here as part of the common power-company rule, paraphrased, not quoted.
Washington-St. Tammany Electric Cooperative, Standard Terms and Conditions for Electric Service (wste.coop), Section 7 (Inspection and Permits): where municipal or other governmental regulations require an inspection certificate or permit approving the member's installation, the certificate or permit shall be obtained before service is made available.
Louisiana Act 881 (2026), R.S. 37:3737 (legis.la.gov): municipalities and parishes enforce only the Uniform Construction Code; licensed private inspectors may conduct plan reviews and inspections under contract with or registration in the jurisdiction.
Stiebel Eltron, Tempra 36 Plus specifications: 36 kW whole-home electric tankless unit, 150 amps total across three circuits at 240 volts.

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A quality quote requires an on-site assessment, period — no figure can be estimated from photos or from this article.

Running out of breaker spaces and running out of service capacity are different problems. Before recommending an upgrade, the electrician calculates the home's electrical demand, including planned additions such as an EV charger, workshop, or electric water heater. That calculation determines whether the service can serve the calculated demand or whether another solution will meet the project's needs.

What pushes a home past 200 amps is usually new load: a home addition, a work shed, or a backhouse or mother-in-law suite, each adding its loads to the same calculation. Switching water heaters can do it too: replacing two 50-gallon tank water heaters, each on a 30-amp double-pole breaker, with two 18 kW tankless units on four 40-amp breakers adds 100 amps to the calculation. Two 60-amp EV chargers add 84 amps to the calculation.

A subpanel can provide additional circuit spaces, but it does not increase the capacity of the existing service.

The homeowner's most useful preparation is a list of existing large appliances and planned equipment. Include what is being added now and what may be added later.

What the Project Changes

The scope starts at the existing service entrance: the meter equipment, service conductors, disconnects, grounding, and panels. This is not just changing the meter over. For overhead service, the riser — the conduit running up the outside wall to the overhead lines — and service-entrance conductors, the conductors carrying power from the meter to the disconnects, are evaluated and upsized as needed. Meter equipment is replaced or confirmed compatible with the approved service. The disconnect arrangement depends on the layout: a single 400-amp main disconnect, or two 200-amp main disconnects. Depending on the equipment, the supply may divide within a meter-main assembly, at a meter socket with listed dual-load terminals, or through approved connections in a trough — a wide metal wireway. From the disconnects, the feeders — the large conductors feeding each panel — run to their panels.

One panel may continue serving the existing house while the other supplies new loads. The electrician determines whether the original panel can remain or should be replaced. If the existing panel stays downstream of a new service disconnect, the electrician checks whether its feeder and grounding-and-bonding arrangement need changes for the new service layout.

A panel can be sound and still be too small for the house it serves. The capacity question stands apart from how long panels last.

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The Short Answer

A 200-to-400-amp service upgrade increases the electrical capacity available to the home. It involves evaluating the existing service, obtaining utility approval, and installing the meter equipment, conductors, disconnects, and panels required for the new layout.

What is commonly called a residential \"400-amp service\" often uses a meter socket rated 320 amps continuous feeding two 200-amp main disconnects, each supplying its own panel. Other arrangements use a single 400-amp main disconnect. The layout depends on the calculated demand, the equipment, and the serving utility's requirements.

The existing panel does not automatically need replacement. Whether it stays depends on its condition and how it fits into the new installation. The serving utility must approve the equipment used at the property, and the authority having jurisdiction (AHJ) — the local jurisdiction responsible for the permit and approval process — handles permitting and inspection.

Two 200-amp breakers alone do not establish the home's allowable total load. The meter socket rating, conductors, load calculation, and utility approval govern that.

Current as of October 24, 2026.

What the Homeowner Is Seeing

The electrical system no longer fits the homeowner's plans. The panel's breaker slots are gone, or the panel technically has space but the home's electrical demand has outgrown what a 200-amp service can serve. An addition is going on the back of a 1960s slab house in Metairie, a workshop is planned in Lafitte, a Northshore home in Covington is getting an EV charger, or the water heater is being switched to a tankless unit — and a whole-home electric tankless heater can be a large load. As one documented example, Stiebel Eltron's Tempra 36 Plus is rated 36 kW at 240 volts, drawing 150 amps total across three circuits.

Lights that dip hard or stay dimmed when the air conditioner starts — not the brief, normal flicker of a large motor's startup draw — are worth mentioning to the electrician: persistent dimming can point to undersized conductors, a long run, loose terminations, or a service being asked to carry more than it was built for. Start by identifying the home's existing service size.

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What Does a 200-to-400-Amp Service Upgrade Involve?

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