Weekly digest #115: service upgrade demand

Why service upgrades are spiking this quarter

Three drivers are pushing service upgrade calls right now: EV chargers, heat pump conversions, and induction ranges replacing gas. A 100A panel that ran a 1990s all-electric house fine cannot carry a 48A EVSE plus a 60A heat pump plus a 40A range circuit. The math does not work, and the load calc under Article 220 confirms it before you pop the meter.

The other driver is insurance. Carriers are non-renewing policies on Federal Pacific Stab-Lok, Zinsco, and some Challenger panels. Homeowners who had no plans to upgrade are getting 30-day notices. Expect the call volume to stay elevated through 2026.

Price your bid assuming the utility drop, meter base, and grounding electrode system all need work. Nine times out of ten on a pre-1975 house, they do.

Load calc: Article 220 done right

Use the standard method (220.42 through 220.55) or the optional dwelling method (220.82) and stick with one. Mixing them is how you end up undersized. The optional method is usually friendlier for all-electric homes because the 40% demand factor on loads above 10 kVA does heavy lifting.

Do not forget 625.42 for EVSE. Continuous load at 125%. A 48A charger is a 60A circuit, and the load calc uses the full 11,520 VA. If the homeowner plans a second EVSE, either size for both now or install an EMS per 625.42(A) and document it.

• General lighting and receptacles: 3 VA per sq ft (220.41)
• Small appliance branch circuits: 1500 VA each, minimum two (220.52(A))
• Laundry: 1500 VA (220.52(B))
• Range: nameplate or Table 220.55 column C for a single range under 12 kW
• Dryer: 5000 VA or nameplate, whichever is greater (220.54)
• HVAC: largest of heat or AC, not both (220.60)
• EVSE: 125% of continuous (625.42)

Service entrance conductors and the 83% rule

310.12 lets you size dwelling service conductors at 83% of the service rating when the conductors carry the entire load of a one-family dwelling. A 200A service can run on 2/0 copper or 4/0 aluminum SER in most jurisdictions. Do not apply 310.12 to a feeder unless it is the main power feeder to the dwelling unit and meets the same criteria.

Check the AHJ before you commit. Some inspectors want the 75 degree C column from 310.16 regardless, and arguing on inspection day costs you a return trip.

Field tip: if you are pulling 4/0 aluminum SER through an attic, keep an eye on 310.15(B) ambient correction. An attic hitting 130 degrees F drops your ampacity fast, and that 200A service quietly becomes a 165A service on paper.

Grounding and bonding on the upgrade

This is where upgrades fail inspection. The existing ground rod may be 4 feet down in broken clay. The water pipe bond may be cut because someone put in a plastic section. The CSST gas line may never have been bonded. Fix all of it before you energize.

250.52(A)(1) through (A)(7) lists every electrode present at the building. You bond all of them together. One rod is not enough unless you can prove 25 ohms or less per 250.53(A)(2), which nobody tests, so drive two rods six feet apart and move on. GEC sized per 250.66, bonding jumper per 250.102.

• Ufer (concrete encased electrode) if accessible: 250.52(A)(3)
• Metal water pipe within 5 feet of entry: 250.52(A)(1)
• Two ground rods, 6 ft apart: 250.53(A)(3)
• CSST bond: 250.104(B), typically 6 AWG
• Intersystem bonding termination at meter: 250.94

Meter base, panel, and working space

New meter bases need a disconnect within sight or on the exterior per 230.85 (2020 and later). This is the emergency disconnect rule and it is non-negotiable in jurisdictions on the 2020 NEC or newer. Label it per 230.85(E).

Panel location matters. 110.26 working space is 3 feet deep, 30 inches wide, 6.5 feet high. Clear. No water heaters, no shelving, no dryers jammed in front. If the old panel was in a closet, you cannot replace it in the same closet on a dwelling per 240.24(D), clothes closets prohibited.

Field tip: take a photo of the existing panel location with a tape measure in frame before demo. If the homeowner later claims you moved the panel unnecessarily, the photo shows why you had to.

Pricing, permits, and the utility coordination

A 100A to 200A upgrade in most markets is running $3,500 to $6,500 right now, higher if the service is underground or the meter relocates. Build in the utility disconnect fee, the permit, and a half-day buffer for the inspection. Some POCOs want 10 days notice for a cut and reconnect, others do it same day. Know your territory.

Pull the permit before you order the panel. If the AHJ is enforcing 2023 NEC, you need surge protection per 230.67 on the service. SPD integrated into the panel is cleaner than a sidecar unit and usually cheaper once labor is counted.

1. Load calc, signed and dated, in the permit packet
2. Utility coordination scheduled before demo day
3. SPD per 230.67 if on 2020 or 2023 NEC
4. Emergency disconnect per 230.85 labeled and accessible
5. Grounding electrode system upgraded, not just reused
6. AFCI and GFCI brought up to current code on affected circuits (210.8, 210.12)

The upgrade is not just a bigger panel. It is the whole service, top to bottom, brought to the code cycle the AHJ enforces. Bid it that way and the job pays.