Weekly digest #165: EV charging news

EVSE load calcs are catching people out

Article 625 is where most EV charging mistakes start. The 125% continuous load rule under 625.41 still trips up techs sizing branch circuits for a 48A charger. That circuit needs 60A of capacity, not 50A, and the OCPD has to match. If you are landing #6 THHN on a 60A breaker for a Tesla Wall Connector or a ChargePoint Home Flex set to max output, double check the terminal temperature ratings on both ends before you call it done.

Service load calcs are the other common miss. NEC 220.57 (added in the 2023 cycle) lets you use the nameplate rating of the EVSE or 7,200 VA, whichever is greater, when adding to an existing dwelling load calc. For multiple chargers, EVEMS (Electric Vehicle Energy Management Systems) under 625.42 can keep you off a service upgrade if the panel is tight.

Watch for panels at 80% of busbar rating before you add a 60A or 80A charger. The 120% rule in 705.12 does not apply to load side EV installs, only to interconnections. A 200A panel with 160A of existing load needs a load management device or a service upgrade, full stop.

GFCI and ground fault protection: what changed

Hardwired EVSE units have integral CCID20 (Charging Circuit Interrupting Device) that trips at 20mA. That satisfies 625.22 for personnel protection on the DC side. But the AC branch circuit feeding the unit is a separate question, and the answer depends on where you mount it.

NEC 210.8(A) and 210.8(F) (outdoor outlets for dwellings) require GFCI protection for receptacles. If you are installing a NEMA 14-50 in a garage or outside, that receptacle needs GFCI. The 2023 code closed the loophole that some inspectors were allowing for dedicated EV outlets. Hardwired units are exempt from the receptacle GFCI requirement, which is one reason hardwiring a 48A unit often makes more sense than a 50A plug.

Tip from the field: if a customer insists on a NEMA 14-50 for portability, spec a GFCI breaker rated for EV duty (Eaton CH or Square D QO have listed options). Standard GFCI breakers nuisance trip on EVSE inrush within weeks.

Conductor sizing and voltage drop on long runs

Detached garages and driveway pedestals are where voltage drop bites. NEC 210.19(A) Informational Note 4 recommends 3% on branch circuits, 5% total. For a 48A continuous load at 240V over 100 feet, you are already at the edge with #6 copper. Bump to #4 if the run exceeds 75 feet and you want to keep the charger pulling full rated current.

Aluminum is fine for feeders to a sub panel, but stay copper from the breaker to the EVSE. The torque specs on aluminum lugs at the EVSE terminal block are tighter than most techs realize, and a loose lug on a 48A continuous load will char a terminal block in under a year.

• 40A charger (32A continuous): #8 Cu THHN, 50A breaker
• 50A charger (40A continuous): #6 Cu THHN, 50A breaker
• 60A charger (48A continuous): #6 Cu THHN, 60A breaker (75C terminations both ends)
• 80A charger (64A continuous): #4 Cu THHN, 80A breaker, hardwired only

Disconnect requirements people forget

NEC 625.43 requires a disconnecting means for EVSE rated over 60A or over 150V to ground. For a typical 48A residential install at 240V, no separate disconnect is required if the breaker is within sight or capable of being locked open. Lockout kits are cheap. Use them.

Commercial installs are different. Any DC fast charger or Level 2 unit over 60A needs a lockable disconnect within sight of the equipment per 625.43(A). Do not rely on the panel breaker if the panel is in another room or behind a locked door.

Bonding, grounding, and EMI on signal wiring

Networked chargers (ChargePoint, Wallbox, Enphase) use Ethernet or RS485 for load management. Run the data cable in a separate raceway or maintain 12 inch separation from the power conductors per 800.133. EMI from a 48A continuous load will corrupt Modbus packets and brick your load sharing setup.

Equipment grounding conductor sizing follows 250.122. For a 60A circuit, that is #10 Cu minimum. If you are running PVC outdoors to a pedestal, do not skimp on the EGC and do not bond the neutral at the sub panel. Separate ground and neutral bars, ground rod at the pedestal if it qualifies as a separate structure under 250.32.

Tip from the field: pull a spare CAT6 even if the customer is not paying for networking today. Half of EV owners add solar within three years, and the EVSE almost always ends up on the energy management network.

Permits, inspections, and utility coordination

Most jurisdictions now require a permit for any EVSE install over 40A. Some POCOs (PG&E, ConEd, Duke) require notification for any Level 2 charger regardless of amperage so they can update transformer load models. Check the utility portal before you energize.

For service upgrades driven by EV loads, the lead time on a 200A to 400A upgrade is running 8 to 16 weeks in most metros as of Q2 2026. Quote accordingly and get the meter spot approved before you commit to a charger install date.

1. Pull the permit before the wire goes in
2. Photograph the panel directory and existing load before adding the EV circuit
3. Document the load calc on the permit (inspectors are asking for it)
4. Verify GFCI or hardwire status matches the inspector's local amendments
5. Hand the customer the EVSE manual and the breaker location in writing