Expect a site-specific estimate rather than a standard price for a 400-amp dual-panel service. The design commonly includes two 200-amp main breaker panels, a utility-approved Class 320 meter socket pan, two 200-amp service or feeder runs, a grounding electrode system that may include two ground rods, and utility transformer work when existing distribution capacity is inadequate. Ask for separate prices for customer-owned electrical work, utility work, permits, engineering, trenching, restoration, and equipment changes.
What a 400-amp dual-panel upgrade includes
A 400-amp service upgrade with two 200-amp panels is a coordinated service entrance project, not simply the installation of a larger breaker. The design must work with the utility's transformer and service conductors, the meter equipment, the service disconnects, the grounding electrode system, and the building's calculated electrical load.
The two panels may serve separate areas, large mechanical equipment, workshops, additions, or industrial-style loads. They do not automatically provide 400 amps to every circuit at the same time. The electrician should perform a load calculation and document how the service rating, panel bus ratings, feeder conductors, and demand assumptions fit together.
Because the work crosses the boundary between customer-owned equipment and utility-owned equipment, the utility should review the proposed service before materials are purchased. Its requirements can control the meter socket, service layout, transformer capacity, conductor route, clearances, and sequence for disconnecting and reconnecting power.
The main cost drivers
The most useful way to evaluate a quote is to identify what work is included and which party controls it. A low electrical bid may exclude utility fees, transformer work, engineering, trenching, pavement repair, temporary power, or finish repairs.
| Project element | What it covers | Why the cost varies |
|---|---|---|
| Load calculation and design | Demand calculation, panel schedule, service layout, and equipment selection | Existing documentation, unusual loads, multiple structures, and engineering requirements |
| Service equipment | Class 320 meter socket pan, disconnects, enclosures, bus equipment, and panels | Utility-approved products, indoor or outdoor location, available space, and weather exposure |
| Twin 200A conductor runs | Two conductor assemblies between the service equipment and the panels or distribution equipment | Length, conductor material, raceway, terminations, bends, temperature conditions, and access |
| Grounding and bonding | Grounding electrode conductor, bonding connections, electrodes, and testing or inspection work | Existing electrodes, soil conditions, building type, grounding electrode availability, and local interpretation |
| Utility work | Transformer evaluation, secondary conductors, meter connection, and service reconnection | Utility ownership, transformer capacity, line distance, poles, trenching, and utility charges |
| Site restoration | Drywall, siding, concrete, asphalt, landscaping, or temporary access repairs | Where the service enters, how conductors are routed, and whether excavation is required |
Request a written scope that identifies the owner of each item. A utility may set its own service-construction charges and contribution rules, while the electrical contractor generally prices the customer-side installation. Those responsibilities vary by utility territory and should be confirmed before signing a contract.
Dual 200-amp panels and Class 320 metering
Two 200-amp main breaker panels require more than two large breakers. The service equipment must provide an approved means of disconnect, suitable overcurrent protection, adequate fault-current ratings, and a layout that meets working-space and access requirements. The exact arrangement may be two service disconnects, grouped equipment, or a utility-approved configuration using service-rated equipment.
A Class 320 meter socket pan is commonly associated with services that exceed the capacity of a standard residential meter socket, but the label alone does not approve a 400-amp installation. The utility may specify a particular socket, jaw configuration, bypass arrangement, enclosure, labeling method, or grouping of disconnects. Confirm the utility's current service manual and approved equipment list.
Space is a frequent hidden cost. The existing service location may not have room for the socket, two panels, service disconnects, surge protection, grounding terminations, and required working clearances. Relocating the equipment can add exterior wall work, longer conductors, conduit, weatherproofing, and interior finish repairs.
Panel selection should also account for future circuits and the actual load profile. If the project includes extensive controls, networking, or automated equipment, coordinate that design early. A whole-home automation wiring and central low-voltage panel plan can affect enclosure space, circuit grouping, and pathways even though low-voltage equipment does not replace the required power distribution equipment.
Twin 200A SER cable feeds
Twin 200A SER feeds can mean two separate service or feeder conductor assemblies, depending on the approved design. Do not assume that any cable marked SER can be used for every portion of the installation. Ampacity, conductor material, terminal temperature ratings, ambient conditions, bundling, physical protection, routing, and the applicable wiring method all affect the permitted conductor selection.
The electrician should identify whether each run is service-entrance conductors or a feeder from service equipment. That distinction affects grounded conductor treatment, disconnecting means, bonding, raceway transitions, and where the neutral-to-ground connection is permitted. Panelboard labels and one-line diagrams should make the arrangement clear for future service work.
Long runs can increase cost through larger conductors, voltage-drop design, larger raceways, pulling equipment, additional supports, and difficult terminations. The project may also require a different wiring method where cable is exposed, outdoors, underground, in a wet location, or subject to physical damage. Manufacturer installation instructions and the adopted electrical code control the acceptable method.
Ground rods, grounding, and bonding
A double ground rod array is a common design approach, but it should not be treated as a universal substitute for evaluating the building's complete grounding electrode system. Depending on the site, available electrodes may include a concrete-encased electrode, metal water piping, building steel, or other electrodes recognized by the applicable electrical code.
Under the National Electrical Code framework, supplemental grounding electrode provisions can apply when a single rod does not meet the applicable resistance condition. The exact installation, spacing, conductor sizing, and testing approach must follow the code edition adopted by the jurisdiction and the inspector's interpretation. Some jurisdictions or utilities may have additional requirements.
The grounding electrode system is different from bonding. Grounding connects the electrical system to the earth through recognized electrodes. Bonding connects conductive metal parts so fault current has a dependable return path to the source and protective devices can operate. A quote should identify the grounding electrode conductor, bonding jumpers, metallic water or gas piping treatment where applicable, and any existing electrodes that will be reused.
Ask the contractor to inspect rather than simply bury existing grounding connections. Corrosion, inaccessible clamps, undersized conductors, painted connection points, and disconnected water-pipe bonds can create inspection problems and may require corrective work.
Utility transformer hookup and service-side work
The utility transformer is often the largest unknown in a 400-amp upgrade. The existing transformer may have enough capacity, or the utility may require a larger transformer, new secondary conductors, a different service connection, pole work, underground equipment, or a service extension.
These tasks are normally controlled by the electric utility rather than the homeowner's electrician. The utility determines its ownership boundary, available fault current, transformer configuration, meter requirements, scheduling, outage procedure, and charges. A contractor can coordinate the process, but cannot promise a transformer result without written utility confirmation.
Before accepting a final price, request the utility's preliminary service response in writing. Confirm the point of delivery, transformer responsibility, required meter equipment, customer contribution, lead time, temporary power needs, and whether excavation or restoration is assigned to the homeowner, contractor, or utility.
Utility transformer work may also affect equipment ratings. The available fault current at the service can influence the interrupting rating required for breakers and service equipment. The electrician should obtain the utility's available-fault-current information when required for equipment selection and permit documentation.
How to compare estimates
Obtain bids from licensed electrical contractors experienced with large service upgrades and utility coordination. The estimate should be based on a site visit, not only the panel count. Give each bidder the same utility information, equipment location, load schedule, and routing assumptions.
- Confirm the calculated service load and list every major load, including motors, heating, EV charging, welders, compressors, pumps, and future equipment.
- Obtain utility approval for the service concept, meter equipment, transformer capacity, and point of connection.
- Require a one-line diagram showing the meter, service disconnects, two 200-amp panels, grounding, and major feeders.
- Ask for separate line items for equipment, conductors, labor, permits, inspection corrections, utility charges, engineering, trenching, temporary power, and restoration.
- Verify the equipment's ratings, listing, enclosure type, dimensions, and compatibility with the utility's approved equipment requirements.
- Confirm outage timing, access requirements, protection of finished surfaces, and the process for restoring power.
Compare exclusions as carefully as prices. A bid that excludes transformer work or concrete restoration may appear lower while carrying more financial risk. Avoid paying the full contract amount before the utility connection, inspection, labeling, and commissioning are complete.
Permits, inspections, and final verification
Service upgrades generally require electrical permitting and inspection, but the exact permit path is controlled by the local authority having jurisdiction. Some projects also require building, excavation, right-of-way, fire, or engineering review. Verify the requirements with the local building department and utility before work begins.
The National Electrical Code is a model code, not a single rulebook automatically adopted without change across the United States. Your jurisdiction may use a different adopted edition or local amendments. Utility construction standards are separate from the electrical code, and manufacturer instructions can impose additional installation conditions.
At completion, retain the approved load calculation, one-line diagram, equipment documentation, inspection approval, utility release, panel schedules, and photographs of concealed grounding or conduit work. These records help future electricians understand the service and can reduce uncertainty during later additions.
Frequently asked questions
Is a Class 320 meter socket enough for a 400-amp service?
Not by itself. The utility must approve the complete metering and service arrangement, including the socket pan, disconnects, conductors, enclosure, layout, and connection to the utility system. A Class 320 designation does not guarantee approval for every 400-amp configuration.
Does a 400-amp service require two 200-amp panels?
No. Two 200-amp panels are one common configuration, but the panel arrangement depends on the load calculation, space, equipment, utility rules, and local code requirements. The panels must be coordinated as part of the approved service design.
Are two ground rods always required?
Not always. The required grounding electrode system depends on the electrodes available at the building, the adopted electrical code, site conditions, and local inspection requirements. Two rods are a common approach in some installations, but the electrician should evaluate the complete system rather than assume rods are the only grounding electrodes.
Who pays for a utility transformer upgrade?
That depends on the utility's tariff, service rules, ownership boundary, project location, and required distribution work. Ask the utility for a written cost responsibility determination before relying on an electrical contractor's allowance.
Can an electrician give an accurate price without a site visit?
Usually not for this scope. Conductor distance, access, service location, grounding conditions, panel space, trenching, utility requirements, and restoration can materially change the cost. A preliminary budget may be possible, but a reliable proposal requires site and utility information.