Hardwired or plug-in?

The code treats EV charging as a continuous load, so the circuit has to be rated at 125 percent of the charger current. Turn that around and a 50-amp circuit permits 40 amps of continuous draw. The NEMA 14-50 is the biggest 240-volt receptacle you will find in ordinary houses, so 40 amps is where cord-and-plug installations stop.This is not a rule manufacturers are working around. It is why the product line looks the way it does: units advertised at 48 amps ship with a conduit knockout and terminal block and no cord. Units advertised at 40 amps usually ship both ways, or with a plug you can remove.One practical consequence: if you want the option of 48 amps later, buy a unit that supports it, install it hardwired, and set it down to match today's circuit. Hardwiring costs almost nothing extra at install time and it keeps the ceiling open.

This is the field observation that should drive the decision more than it does. A range receptacle sees a hard draw for an hour at dinner and then nothing. A charger receptacle carries near-maximum current for six to ten hours a night, and the contact springs are the thing that gives up. Scorched 14-50 faces are common enough that most electricians who do EV work have a strong opinion about which receptacles they will install.If you go plug-in, buy an industrial-grade receptacle rather than the cheapest one on the shelf. The difference is a small number of dollars against a job that already costs over a thousand, and it addresses the single most likely failure in the whole installation.It also matters how the plug is treated. A cord that is plugged and unplugged regularly wears the contacts faster than one left in place. If the unit will live in one spot forever, that is an argument for hardwiring it and being done.

In the 2020 and later editions of the code, a 240-volt receptacle in a garage or outdoors requires ground-fault circuit interrupter protection, and Article 625 requires it specifically for receptacles installed to serve EV supply equipment. So a plug-in install usually means a GFCI breaker.Meanwhile the charger has its own ground-fault protection built in, because that is what its listing requires: a charging circuit interrupting device that trips at a much higher leakage threshold than a GFCI breaker. Two detectors of different sensitivity on the same circuit, one of which self-tests, is exactly the configuration that produces trips nobody can explain.That is not a reason to delete the GFCI, and anyone advising you to is telling you to remove personnel protection from an outdoor 240-volt connection. It is a reason that converting a plug-in installation to hardwired is the standard field fix for chronic tripping, because it removes the receptacle and with it the receptacle rule.

If you rent, or you expect to move within a few years, a plug-in charger is an appliance and a hardwired one is an improvement to somebody else's house. Unplug it, put it in the car, screw the bracket to the wall at the next place. A landlord is also far more likely to approve a receptacle than a fixed piece of equipment.The second version of the argument is about the hardware, not the house. Charging equipment gets better and connectors change. A plug-in unit that fails or becomes obsolete is a fifteen-minute swap you do yourself. A hardwired one is a service call.There is a third, quieter case: the receptacle is useful for other things. A 14-50 in a garage runs a welder, a compressor or an RV. If you were going to want that circuit anyway, put a receptacle on it.

Cost is deliberately absent from that list, because the difference is small and it goes both ways. A receptacle and an in-use cover cost money that hardwiring does not. A GFCI breaker costs more than a standard one. Hardwiring saves both and adds nothing but a few minutes of termination. Anyone quoting a large price difference between the two is quoting something else.