Voltage Drop Calculator for Maryland
NEC 2020 voltage drop math for EV charger installers working in Maryland.
Maryland EV installs frequently push past 100 ft of conductor — detached garages, parking-lot DCFC pedestals, and multifamily carport runs all add distance. NEC 2020 recommends a 3% branch / 5% total voltage-drop ceiling.
Worked example for Maryland
A 48 A Level 2 charger at 120 ft on 240 V single-phase #6 Cu shows roughly 2.4% drop. That's below the 3% NEC recommendation, so you'd stay at #6. Maryland's 0.88× ampacity correction is independent of voltage drop but applies on the same conductor pick.
Code & Utilities
EV installations in Maryland are governed by the 2020 National Electrical Code, in force since 2022. That includes Article 625 (Electric Vehicle Power Transfer System) requirements: 125% continuous-load sizing on EVSE branch circuits, GFCI protection at outdoor receptacles, and provisions for energy management systems on shared circuits.
In Maryland, you'll most often interconnect with BGE, Pepco, Delmarva Power, Potomac Edison. Always verify the applicable tariff and any utility-specific requirements (CT cabinets, metering enclosures, demand limiters) at design time.
Climate & Ampacity
In Maryland, the 91°F summer ambient drives a 0.88× 75°C ampacity correction. Bake this into every Level 2 and DCFC conductor pick before you commit to a wire size. Because the correction is below 0.9, conductors that "look fine" on a 30°C ampacity table will not carry their nameplate current here — always derate explicitly.
Maryland takeaway
Voltage drop is a recommendation, not a hard NEC rule — but EVSEs throttle aggressively below ~228 V on a 240 V circuit, so customers in Maryland will notice any drop above 5%.