EV charger install questions
Short answers first, from the NEC 2023 data ChargeSpec uses. Your electrician and the authority having jurisdiction make the final call on any install.
What is ChargeSpec?
ChargeSpec is an Android app by Sonicon Software for US electricians and EVSE installers. For one EV charger job it works out the branch-circuit load, conductor, breaker and voltage drop from NEC 2023 data, can check the dwelling service load, and produces a US Letter spec sheet. It is a calculation record, not a permit.
What size wire does a 48 A EV charger need?
A 48 A charger is a 60 A continuous load. With 75 °C insulation and terminations at 30 °C ambient, 6 AWG copper is rated 65 A. In the 60 °C column, 6 AWG copper is rated 55 A, so ChargeSpec steps up to 4 AWG (70 A). A long run may need larger wire for voltage drop.
See the conductor step for how the column and ambient correction work, and the voltage drop step for long runs.
What size breaker does a 48 A EV charger need?
ChargeSpec sizes the breaker from the 125% continuous load: 48 A × 1.25 = 60 A, and 60 A is a standard rating under 240.6(A), so it selects a 60 A breaker. If the breaker is larger than the conductor's ampacity, the conductor steps up.
Why is an EV charger circuit sized at 125%?
EV supply equipment counts as a continuous load, so the branch circuit is sized at 125% of the charger's rating. ChargeSpec applies a 1.25 factor from its NEC 2023 data and shows 625.41 and 210.19(A)(1) as the basis. The wire and breaker are sized from that figure.
How does ChargeSpec calculate voltage drop?
It multiplies 2 × the charger's rated amps × the conductor's resistance per 1,000 ft (NEC Chapter 9, Table 8) × the run length, then divides by the supply voltage for the percent. It is a single-phase, two-wire, resistance-only method. Above 3%, it suggests the smallest larger conductor that brings the drop to 3% or less.
Is a voltage drop over 3% a code violation?
No. ChargeSpec flags a branch drop above 3% and above 5%, and labels both “efficiency guidance, not a code violation”, citing the 210.19 informational note. It doesn't take a feeder drop as input, so account for the feeder's share yourself when you judge the combined drop.
Can a 200 A service take an EV charger?
It depends on the rest of the house. ChargeSpec Pro runs the NEC 220.82 optional method for a 240 V dwelling, adding the charger at the larger of 7,200 VA or its nameplate. The result is pass with headroom or fail with shortfall in amps. The in-app sample, a 2,000 sq ft house, passes 200 A.
The sample house has 2,000 sq ft, two small-appliance circuits, one laundry circuit, 5,000 VA of fastened appliances, 15,000 VA of heating and a 48 A charger. Your result depends on your own inputs.
Does ChargeSpec work with aluminum wire?
Yes. Choose aluminum and ChargeSpec uses the aluminum columns of Table 310.16 (12 AWG and larger) and aluminum resistance for voltage drop. For the same 60 A load at 75 °C, it selects 4 AWG aluminum, rated 65 A, on a 60 A breaker.
Which NEC edition does ChargeSpec use?
NEC 2023 only. Every result is labelled “NEC 2023 data”, and the spec sheet carries the same label. If your jurisdiction is on another edition or has local amendments, check the values against the code it has adopted and with the authority having jurisdiction.
What is free and what needs Pro?
The load, conductor, breaker and voltage drop results are free. A one-time Pro unlock, bought through Google Play, adds the dwelling service load check and spec-sheet export, print and share. Without Pro you can still preview the spec sheet. There is no subscription and no account.
Does ChargeSpec estimate charging time or cost?
No. ChargeSpec is an install calculator for the electrician wiring the charger. It doesn't estimate charge time or charging cost, and it isn't a map of public chargers. It covers the circuit: load, wire, breaker, voltage drop, service load and the spec sheet.
Does ChargeSpec need an account or send my data?
No account. The calculations run on your phone, and the app's own code sends nothing over the network. Google Play handles the Pro purchase, which is why the app holds the internet permission. A spec sheet leaves the phone only when you save, print or share it. Details are in the privacy policy.
Run the numbers on your own job.
