Conduit Fill Calculator for New Hampshire
NEC 2020 conduit fill math for EV charger installers working in New Hampshire.
Multifamily and workplace EV installs in New Hampshire routinely stack several #6 or #8 AWG home runs in shared EMT — at which point NEC 2020 Chapter 9 fill rules and 310.15(C)(1) adjustment factors both kick in.
Worked example for New Hampshire
Stacking 3 × #6 AWG THWN-2 home runs (each with 2 conductors + EGC) in a single EMT means the raceway sees 6 current-carrying conductors. That triggers a 1.0× ampacity adjustment, on top of New Hampshire's 0.88× temperature correction. Fill itself stays under the NEC 40% ceiling at roughly 1¼" EMT.
Code & Utilities
New Hampshire currently enforces the NEC 2020 edition, adopted in 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.
New Hampshire's primary EV-relevant utilities are Eversource New Hampshire, Unitil, New Hampshire Electric Cooperative. Each has its own service-upgrade timeline, EV rebate availability, and metering rules — confirm them before quoting commercial work.
Climate & Ampacity
New Hampshire's representative summer design ambient is around 87°F, which yields a 0.88× ampacity correction factor at 75°C terminations per NEC 310.15(B)(1). 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.
New Hampshire takeaway
Always run the conduit-fill math first when laying out a multifamily EVSE rack — it's the constraint that most often forces a re-spec from #6 to #4 or from EMT to a larger trade size.