I learned the hard way that the 14-50 receptical needs to be industrial grade. It’s not just the plugging and unplugging that is a risk. It’s the 7 -10 hours of current flow at 40 amps. They cost $70-90 at the supply house and are rated to deliver 40 amps 24-365. They are bigger and require a different faceplate. Could have burned my house down if it wasn’t concrete.