Master electrician guide to wiring a smart panel

Load Calculation and Panel Sizing

Start with a proper load calc per NEC Article 220. Smart panels like the Span, Leviton Load Center, or Schneider Square D Energy Center still live under the same rules as any other service equipment. Size the service based on the dwelling load, not the marketing sheet.

For a typical single-family retrofit, run a standard calc under 220.82 or an optional calc under 220.83 if you are adding loads to an existing service. EV chargers and heat pumps are the usual culprits pushing homes over 200A. A smart panel with load management under 750.30 can sometimes keep you at 200A service without an upgrade, but the AHJ has final say.

• Confirm service conductor ampacity per 310.12.
• Verify main breaker rating matches the busbar, not just the enclosure label.
• Document managed circuits in writing for the inspector.

Rough-In and Conductor Management

Smart panels are deeper and wider than standard load centers. Measure the rough opening before you demo drywall. Span panels need roughly 6 inches of depth plus working space per 110.26. Leave a minimum 30 inch wide, 36 inch deep clear zone in front, with 6.5 feet of headroom.

Cable management matters more than in a dumb panel. The control board, CTs, and ribbon cables eat real estate. Land your neutrals and grounds on the far bars, keep hots short and dressed, and leave service loops for the CTs that clamp each branch.

Dress every circuit to its final breaker position before you energize. Re-routing a 50A feeder after the cover goes on means pulling the guts twice.

Grounding, Bonding, and the MBJ

Grounding rules do not change because the panel has Wi-Fi. Service equipment still needs a main bonding jumper per 250.24(B), and the grounded conductor terminates on the neutral bar ahead of any switching. On a Span Panel, the main lugs and the main breaker position are fixed, so the MBJ install is documented in the manual. Follow it.

If you are installing the smart panel downstream as a subpanel, isolate neutrals from grounds per 250.32(B)(1). This trips up crews who assume the fancy panel is always the service. Check the one-line before you land anything.

1. Identify whether the unit is service equipment or a subpanel.
2. Install or remove the MBJ accordingly.
3. Verify the GEC sizing per 250.66 from the grounding electrode system.
4. Bond any metallic raceway and water piping per 250.104.

Branch Circuits, AFCI, and GFCI

Most smart panels use proprietary solid-state or hybrid breakers. Some include AFCI and GFCI protection in firmware, others still need listed breakers. Read the listing. A breaker that advertises "smart protection" is not AFCI unless it is listed to UL 1699.

GFCI requirements under 210.8 and AFCI requirements under 210.12 apply to the outlet or circuit, not the panel brand. Kitchens, bathrooms, garages, outdoors, laundry, and within 6 feet of a sink all need GFCI. Bedrooms, living rooms, and most habitable spaces need AFCI. If the panel firmware provides it, confirm the listing covers the specific circuit type.

EV, Battery, and Load Management

This is why most customers are paying for a smart panel. Article 750 covers Energy Management Systems, and 625.42 permits EVSE load management to reduce calculated demand. A 60A EV circuit can be managed down to fit within available capacity, provided the EMS is listed and configured correctly.

For battery integration, Article 706 applies for ESS, with interconnection under 705. A Span panel with a backup battery like an Enphase or Tesla setup needs the 120% rule checked on any bus you are backfeeding, per 705.12(B)(3). The smart panel changes how loads are shed during outage, but it does not change the interconnection math.

Label every managed circuit at the breaker and at the load. Three years from now a different sparky will open this panel, and the inspector will ask how the 100A service runs a 48A charger and a 5 ton heat pump.

Commissioning and Handoff

Power up in sequence. Energize the main, verify voltage and phase rotation, then bring branches up one at a time while the app binds each circuit. CT direction matters. A reversed CT reads negative power and will confuse the homeowner on day one.

Walk the customer through the app before you leave. Show them how to identify a tripped breaker, how to shed a load, and where the manual disconnect is. Hand over the panel schedule, the EMS configuration printout, and any AHJ documentation for managed loads.

• Verify torque on every lug per the manufacturer label and 110.14(D).
• Test GFCI and AFCI function on every required circuit.
• Confirm remote shutoff works from the app and from the physical disconnect.
• Leave the as-built panel schedule inside the dead front.

Smart panels are still panels. The code does not bend for firmware. Size the service, bond correctly, protect the circuits the code requires, and document the load management in writing. The tech is new, the fundamentals are not.