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Building Code Reference

Got a CEC 230 correction?

Electrical service entrance

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

CEC Article 230 governs electrical service entrances in California buildings. It covers everything from the utility's service drop or underground lateral, through the meter base and service entrance conductors, to the main disconnect. Every component must be rated for the calculated load, and that load calculation must follow CEC Article 220. Plan-checkers flag Article 230 corrections when service size (100A vs. 200A vs. 320A) isn't backed by a load calculation on the submitted plans.

How to fix it

  1. Draw a complete electrical one-line diagram

    Draw a complete electrical one-line diagram showing the utility service point, meter base, service entrance conductors, and main disconnect. Label each component with its ampere rating, voltage, wire size (AWG or kcmil), conduit size, and the applicable CEC section. The one-line must be on its own sheet or clearly noted on the electrical plan — not buried in a detail that's hard to find. Plan-checkers in most OC cities want to see the one-line on the E-1 sheet before they'll even start reviewing the panel schedule.

  2. Complete a load calculation per CEC Article 220

    Run a load calculation per CEC Article 220 and put it on the plans. Use the standard method (Article 220.40) for general loads, or the optional method for single-family dwellings (Article 220.82) if it results in a smaller service size. Show every load category: lighting (3 VA per sq ft for general), small appliance circuits (1,500 VA each, minimum two), laundry, HVAC, water heater, EV chargers, and any large fixed equipment. Apply the correct demand factors. Show the total calculated load in amperes at 240V and how the proposed service size covers it with margin. Most plan-checkers want a tabular load schedule, not just a note referencing code.

  3. Match service size to the calculated load

    Confirm your service size meets or exceeds the calculated load. For typical single-family homes in California, 200A at 240V is the practical minimum — load calcs on 1,500 to 2,500 sq ft homes almost always justify it. If the calc yields over 200A due to EV chargers, heat pumps, or large HVAC systems, spec a 320A or 400A service and state it on the plans. Conversely, if you are sizing a 100A service for a smaller structure like a garage or accessory building, the load calc must show the calculated demand is below 100A. Without that math, the plan-checker cannot approve the service size regardless of what you have drawn.

  4. Specify service entrance conductor type, size, and insulation

    List the conductor type, size, and insulation rating on the one-line and in the panel schedule notes. Most residential service entrance installations use aluminum — either type SE cable or XHHW-2 conductors in conduit. CEC 230.23 sets the minimum conductor size at 8 AWG copper or 6 AWG aluminum for single-family residential services. For 200A service, you're typically looking at 4/0 AWG aluminum or 2/0 AWG copper conductors under CEC 310.12. State whether conduit is EMT, PVC Schedule 40, or rigid metallic, and confirm conduit fill does not exceed NEC Chapter 9 limits. Leaving conductor details off the plans is one of the most common reasons for an Article 230 correction.

  5. Locate and label the main service disconnect on plans

    Mark the main disconnect location on the floor plan or site plan and label it 'Service Disconnecting Means per CEC 230.70.' CEC 230.70 requires the disconnect to be installed at a readily accessible location, either outside the building or inside nearest the point of service entrance. If using a meter-main combo unit mounted on the exterior, note that explicitly — it satisfies both the metering and disconnect requirements in one enclosure, and can also serve as the outdoor emergency disconnect CEC 230.85 requires for one- and two-family dwellings. Unlabeled disconnects are an automatic flagged correction.

  6. Note meter base spec against utility metering standards

    Draw the meter base on the plans and note the metering standard it must meet. For Southern California Edison service areas, reference the SCE Electrical Service Requirements (ESR) manual. For SDG&E areas, reference SDG&E Rule 16. The plan-checker may not scrutinize meter base specs closely, but the utility inspector will. A meter base that does not match the utility standard causes a field rejection even after permit issuance. Typical residential specs: 200A single-phase, ringless socket-type, with current transformers (CTs) if required for larger services above 200A.

  7. Account for new large loads before finalizing service size

    If the project adds EV charging, solar PV with battery storage, a heat pump water heater, or a new HVAC system, run the load calc with all those loads included before locking in the service size. A 200A service that was adequate for an older home often comes up short after a Level 2 charger (7.2 kW), a 3-ton heat pump (approximately 20A), and a heat pump water heater (4.5 kW) are added. Show the updated load calculation on the plans reflecting all proposed new loads. Plan-checkers are increasingly flagging under-sized service entrances on remodel permits that add significant electrical loads.

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Why you got flagged

Plan-checkers flag CEC 230 corrections most often when the submitted plans show a panel and meter base but skip the load calculation entirely. Without a load calculation per Article 220, the plan-checker has no basis to approve the proposed service size. A 200A service panel drawn on the electrical plan means nothing if the load schedule isn't there to justify it.

The second common trigger is a mismatch between the service size on the panel schedule and the actual calculated load. If your load calc comes out at 175A but you spec a 100A main breaker, that's an automatic correction. The same goes in reverse — over-sizing without documentation raises code questions about the incoming conductors and the utility coordination.

Service entrance conductor sizing is another failure point. CEC 230 requires the conductors from the utility connection point to the main disconnect to be sized per the calculated load. Contractors sometimes spec the panel correctly but draw service entrance conductors that are one size short, or leave conductor sizing blank entirely on the one-line diagram.

The fourth scenario is a missing or mislabeled main disconnect. CEC 230.70 requires the main disconnect to be in a readily accessible location and clearly labeled as the service disconnecting means. Plans that show a main panel without identifying the disconnect location or labeling it properly will get flagged — plan-checkers need to confirm the disconnect is within the first 10 feet of the service entrance point.

The official code

California Electrical Code (Title 24, Part 3), Article 230 — Services

Read the source →

Common questions

Does CEC Article 230 require a load calculation for every electrical permit?
For any permit involving a new service installation or service upgrade, yes. A load calculation per CEC Article 220 is required to justify the proposed service size. For permits that do not touch the service — like adding a circuit or replacing a fixture — you do not need a new load calc. But if you are pulling a service change permit, an upgrade from 100A to 200A, or a new construction electrical permit, the load calc is required and must appear on the submitted plans.
What is the minimum service size for a single-family home in California?
CEC Article 230 does not set a fixed minimum service amperage. The service must be sized to the calculated load per Article 220. In practice, load calcs on typical California single-family homes of 1,500 sq ft or larger almost always yield a calculated demand over 100A, making 200A the de facto standard. Many plan-checkers and AHJs in California treat 200A as the practical minimum for new SFR construction. If you are adding EV charging, solar, or heat pumps, your calc may push you toward 320A or 400A service.
Where exactly does the main disconnect have to be located under CEC 230?
CEC 230.70 requires the service disconnecting means to be at a readily accessible location either outside the building or inside nearest the point of service entrance. The service entrance conductors running inside the building must reach the disconnect within the first 10 feet after entering the structure. Practically speaking, most residential installations put the disconnect right at the meter-main combo on the exterior wall. If the panel is inside, the conductors run in from the meter base and the main breaker must be within 10 feet of where they enter. The disconnect must be clearly labeled as the service disconnecting means.
Can aluminum conductors be used for residential service entrance?
Yes. Aluminum conductors are standard for residential service entrance and are specifically addressed in CEC 230. Type SE cable with aluminum conductors, or XHHW-2 aluminum in conduit, are both common. For 200A service, the typical spec is 2/0 AWG aluminum conductors. Aluminum is fine for the service entrance conductors from the meter base to the main disconnect and panel, but use copper for the branch circuit wiring downstream. Note the conductor material explicitly on your electrical plans — plan-checkers want to confirm the aluminum conductors are properly sized and that terminations are rated for aluminum.
Does adding an EV charger require a service upgrade under CEC 230?
It depends on your current load and available panel capacity. CEC 230 requires the service to be sized for the total calculated load, including any new loads you are adding. A Level 2 EV charger typically draws 7.2 kW (30A at 240V) continuously. If your current panel has available capacity and the existing service supports the added load in the Article 220 calculation, you may not need a service upgrade. If the calc shows you are over capacity, you will need to upsize. Some jurisdictions have load management provisions that let you install EV charging with a demand management device without full service upgrade — check with your AHJ before committing to a full panel change.
How many service disconnects are allowed under CEC 230?
CEC 230.71 limits the number of service disconnecting means to a maximum of six disconnects grouped in a single location. For most residential installations, one main disconnect (the main breaker) satisfies this. Multi-tenant or mixed-use buildings sometimes have multiple meters and disconnects — all must be grouped at the service entrance location. Plan-checkers flag layouts where disconnects are spread across different parts of the building, since that makes it impossible for emergency responders to quickly cut power at a single point.

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