I posted on here the other day about some suspicious 240v cable and followed the recommendations to replace it. I was already leaning that way but was kind of hoping to be told I was overthinking it. But you all confirmed what I thought. I ran close to 25’ of 10/2 cable from the second story to the basement. Nothing is wired yet because it is late and I don’t want to turn on the main breaker.
My step dad let me borrow a 50’ fishing tape and 10’ endoscope which were really helpful. I did not have to cut any walls!
Since you went with 10/2 for a 240v outlet that means your cable will have two hots and a single ground. But the cable you bought will have a black, white and bare/green wire. Make sure that you wrap both ends of the white conductor with red electrical tape to indicate that it is also a hot wire. White normally indicates a neutral, but since you won’t have a neutral wire in this cable, it’s important to mark it. Otherwise someone else may work on this outlet in the future, see a white wire, assume it’s a neutral, wire something up with it as a neutral, and give themselves a pretty bad shock.