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A hardwired charger is wired directly into the electrical panel. It allows for the fastest residential charging speeds (48 amps to 80 amps) because it eliminates the physical resistance of a plug connection. It is also required for outdoor installations where rain is a factor.
A plug-in setup uses a NEMA 14-50 receptacle. While convenient if you plan to move soon, it is limited to a 50-amp circuit (40 amps of charging). Furthermore, cheap hardware-store receptacles are not rated for continuous EV loads and can melt. If you go the plug-in route, the electrician must use an industrial-grade Hubbell or Bryant receptacle ($80).
Crucially, the 2020/2023 National Electrical Code requires GFCI breakers for all 240V garage receptacles. EV chargers already have built-in GFCI protection. When you plug a GFCI charger into a GFCI breaker, they often conflict and randomly trip, leaving your car uncharged in the morning. Hardwired chargers bypass the GFCI breaker requirement entirely.