EV charger install calculator for electricians

Load, wire size, breaker and voltage drop for one EVSE job, from NEC 2023 data. It ends in a spec sheet you can hand to the inspector or the customer.

Free to download. Load, wire, breaker and voltage drop results need no purchase. A one-time Pro unlock adds the service load check and spec-sheet export.

Charger 48 A · 240 V

NEC 2023

48 A → 60 A
6 AWG Cu
60 A breaker
4.91%

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. It can check the dwelling service load and produce a US Letter spec sheet. It is a calculation record, not a permit or sign-off.

What it works out

Enter the charger's rated amps and the supply voltage. ChargeSpec works out the continuous load at 125%, the conductor that carries it after ambient correction, and the next standard breaker at or above the load, stepping the conductor up if needed. It then gives the voltage drop over your run. Pro adds the dwelling service check and a spec sheet.

Load

Rated amps × 1.25 is the branch-circuit load the wire and breaker are sized from.

NEC 2023 data
625.41
210.19(A)(1)

Wire

Copper or aluminum, insulation and termination temperature, ambient correction. The lower of the two temperature ratings sets the column.

NEC 2023 data
Table 310.16
310.15(B)(1)
110.14(C)

Breaker

The next standard size at or above the load. If the breaker is larger than the conductor's ampacity, the conductor steps up.

NEC 2023 data
240.6(A)
240.4

Voltage drop

Volts and percent over the run. Above 3%, it shows a larger conductor that brings the drop under 3%.

NEC 2023 data
210.19 Info Note

Service load

Pro

The NEC 220.82 optional method with the charger included: pass or fail, with headroom or shortfall in amps.

NEC 2023 data
220.82
220.57

Spec sheet

Pro

A US Letter PDF with inputs, results, the NEC 2023 label, the date and a professional-use disclaimer. Save, print or share it. Free users can preview it.

Every answer shows its code basis

Each result on the ticket carries the label "NEC 2023 data" and the code sections it rests on: 625.41 and 210.19(A)(1) for the load, Table 310.16, 310.15(B)(1) and 110.14(C) for the conductor, 240.6(A) and 240.4 for the breaker, the 210.19 informational note for voltage drop, and 220.82 and 220.57 for the service.

Load

60 A

NEC 2023 data
625.41
210.19(A)(1)

Continuous load: 125% of 48 A rated

One job, worked through

60 A load
A 48 A charger on 240 V is a 60 A load.
6 AWG copper
6 AWG copper, 75 °C column, shows 65 A and carries it.
60 A breaker
The 60 A breaker protects that conductor.
Protected
4.91%
Over a 250 ft run the drop is 4.91% (11.8 V), above 3%. 3 AWG brings it to 2.45%.
Above 3%
54.5 A headroom
Pro: on the sample 200 A dwelling, the service check passes with 54.5 A headroom.
Pass

The voltage-drop warning is efficiency guidance, not a code violation.

Wire and breaker boxes: 6 AWG copper at 75 °C rated 65 A, and a 60 A breaker marked protected.

Voltage drop on a 250 ft run: 4.91%, 11.8 V, above 3%, with 3 AWG suggested at 2.45%.

What ChargeSpec is not

Not a public-charger map.
No charge-time or charging-cost estimates.
Not a general electrical calculator suite.
Not tied to your local code: it uses NEC 2023 data only, and your jurisdiction may be on another cycle or a local amendment.
Not the adopted code, a permit or a sign-off. ChargeSpec is a calculation record for professional use.

Built for the job site

The whole job sits on one ticket: enter the charger once and every box below it fills in.

Canary by day and carbon-dark at night, following your phone's theme, with large controls and heavy figures you can read at arm's length in a panel room.

Pass, fail and warning each carry a word, not only a colour.

Privacy in one paragraph

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. A spec sheet leaves the phone only when you save or share it. Read the privacy policy.

EV charger install calculator for electricians

What it works out

Load