1. GFCI protection expansion — 210.8(B)(6)–(12)
The single biggest material impact. GFCI protection is now required for a much wider set of commercial locations: indoor wet or damp locations, laundry areas, indoor kitchens, dishwasher circuits, rooftop outlets, and accessory buildings. On a 90k SF mixed-use project, we saw GFCI device quantity roughly double compared to a 2020 NEC takeoff.
Takeoff implication: a standard 20A duplex receptacle ($2.80 material) becomes a 20A GFCI duplex ($18-$24 material). On 180 receptacles in the expanded scope, that is a $3,000-$3,800 material swing that should not be left to a fudge factor.
2. Article 210.8(F) — outdoor outlets for 1- and 2-family dwellings (and its reach)
This article technically addresses dwellings, but the AHJ in several jurisdictions has extended it to multifamily and mixed-use projects. The upshot: every outdoor receptacle — not just wet-location — now requires GFCI. For multifamily, that means podium-level balcony receptacles, courtyard outlets, and exterior maintenance receptacles all upgrade.
3. Conduit fill — Chapter 9 Table 4 updates
The 2023 edition quietly revised cross-sectional area values for several trade sizes of EMT and rigid. The 1¼" EMT and 2" rigid rows both saw minor reductions in allowable fill — small numbers, but enough to push some borderline 40% fills into code-violation territory.
Takeoff implication: rerun any saved assemblies that use 1¼" EMT for 3×10 AWG THHN plus ground. What was 40% fill in NEC 2020 may now be 42% fill in NEC 2023. Upsize to 1½" EMT or flag for redesign.
4. Neutral current calculations — 220.61(C)
The harmonic content exemption for 3-phase 4-wire LED lighting circuits was tightened. The old 70% demand reduction for the neutral is no longer blanket — you need to document that the LED drivers meet a THD threshold. In practice this means more neutrals carrying closer to full-phase current on modern lighting loads.
Takeoff implication: on a large lighting job, you may find yourself upsizing neutrals from #10 AWG to #8 AWG across dozens of circuits. The labor unit impact is negligible per circuit, but at 180 circuits it adds up.
5. EV charger circuit requirements — Article 625
Article 625 saw substantial rework. Any commercial project with EV charging parking (which is increasingly required by local codes in CA, OR, WA, NY, MA) now has specific circuit requirements including continuous-load 125% rules, load management system requirements for multi-port installs, and dedicated overcurrent protection.
Takeoff implication: EV charger circuits are no longer a line item you can bolt on at the end. On a 40-stall EV-ready parking garage, the circuit count, panel capacity, and feeder sizing implications touch multiple panels and potentially the service entrance.
"The GFCI expansion alone added $18,000 to our device cost on a mid-size multifamily bid. If you're still estimating against NEC 2020, you're not competitive and you're not compliant."
Derek Monroe, Chief Estimator, Summit Electric Associates — Phoenix, AZ
6. Surge protective devices — 230.67
Type 1 SPDs are now required at the service entrance for dwelling units and certain commercial applications. This was previously optional in most jurisdictions. On a 320-unit multifamily, that is 320+ new SPD line items, each with installation labor.
7. Emergency disconnect — 230.85
Outside emergency disconnects for 1-family dwellings and certain multifamily configurations. Material is modest ($400-$800 per unit) but the labor to install a compliant NEMA 3R enclosure with proper working clearance is non-trivial.
How to audit your estimating assemblies
If you have a saved assembly library (Accubid, ConEst, McCormick, or internal), the six items below are the minimum audit list before your next bid that references NEC 2023:
- Walk every GFCI receptacle assembly and verify 2023 scope coverage.
- Rerun conduit fill validation on any 1¼" EMT assemblies with 3+ conductors.
- Update neutral sizing defaults on 3-phase 4-wire LED circuits to remove the blanket harmonic exemption.
- Add EV charger assemblies with 125% continuous-load sizing and feeder impact.
- Add Type 1 SPD line items to service-entrance assemblies.
- Add emergency disconnect assemblies to applicable residential/multifamily assemblies.
Jurisdiction adoption varies
As of Q2 2026, 31 states have adopted NEC 2023 statewide, with another 9 in partial adoption. Four states are still on NEC 2020 and one is still on NEC 2017 (NY will adopt 2023 in January 2027). Always verify with the AHJ before you bid — it is on you, not the owner, to estimate against the right code edition.