TradesHow this works
A Level 2 charger runs for hours, so the code counts it as a continuous load and sizes the wire and breaker at 125 percent of the charger's current. Enter the charger's set output and the tool gives the circuit amps, the wire size, and the breaker, plus the charging power at your voltage.
It also settles the two decisions. Under 40 amps you can plug into a 14-50 or hardwire; at 48 amps you must hardwire. And because wire is cheap next to a second rewire, it offers a future-proof build sized for a 48 amp charger so a later upgrade is just swapping the unit. It stops at planning grade, so confirm the panel has the capacity and check the run for voltage drop.
Common questions
What size wire and breaker for a 48 amp EV charger?
An EV charger is a continuous load, so NEC 625.42 sizes the circuit at 125 percent of its current. A 48 amp charger needs a 60 amp circuit, which is 6 AWG copper on a 60 amp breaker. A 40 amp charger needs a 50 amp circuit, 8 AWG on a 50 amp breaker. The tool sizes it for the charger and material you enter.
Can I plug in my EV charger or does it need to be hardwired?
A plug-in charger on a NEMA 14-50 receptacle is limited to a 40 amp draw, because the 50 amp receptacle circuit can only carry 40 amps continuously. If you want a 48 amp charger, it has to be hardwired. Plugging in is flexible and easy to inspect, hardwiring unlocks the higher current, so the choice comes down to how fast you want to charge.
Should I wire for a bigger charger than I have?
It is often worth it. Pulling 6 AWG on a 60 amp breaker now, even for a smaller charger, means a future upgrade to a 48 amp unit is just swapping the charger rather than rewiring the run. The extra cost is a size or two of wire today against a full rewire later. The tool offers the future-proof build alongside the exact one so you can weigh it.
Sources: NEC (NFPA 70) 625.42 / 210.20(A): EVSE continuous load, 125% (2023) · NEC Table 310.16 ampacity + 240.6 breaker sizes (via necData) (2023). Engine version 1.0.0. Risk tier 2.