Weird 2-Phase Wiring

I was looking in the service panel to label all breakers.

It has 30A breaker for drier, which is connected to 12-2 BX cable. Two hot wires from the breaker connected to black and white wires and the neutral from the panel is connected to the BX shield of the cable. Looks like professional job. I am not an electrician, but this seems strange. I would expect 12-3 wire instead and no link between shield and neutral.

Is this something unusual and should I call electrician to look at it?

By bobjohn |