Correct wiring for a 50 amp pulls from opposite legs of a 240 circuit. And since this is AC, when one leg is at +120, the other is at -120. If you have both legs maxed out at 50 amps, the neutral leg will sum out to 0 amps - all the current is going via the two hot legs.
If your electrician managed to hook up both wires to the same leg, then you would overload the neutral wire. But there "should" be no way to do this with a standard 50 amp breaker. When these snap into the panel, they grab opposite legs.
2021 Isata 5 28SS with 2020 JLU Rubicon pusher
Prior: 2016 Lance 1995 / Ram 1500 Eco Diesel
2012 Lance 1575 / 2015 Jeep JKU Rubicon